JP3063754B2 - Image data interpolation device, image data interpolation method, medium recording image data interpolation program - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data interpolation device, an image data interpolation method, and a medium in which an image data interpolation program is interpolated at a predetermined magnification for image data composed of dot matrix pixels.

[0002]

2. Description of the Related Art When handling images on a computer or the like,
An image is represented by pixels in a dot matrix, and each pixel is represented by a gradation value. For example, photographs and computer graphics are often displayed on a computer screen with 640 dots in the horizontal direction and 480 dots in the vertical direction.

On the other hand, the performance of a color printer has been remarkably improved, and its dot density is extremely high, such as 720 dpi. Then, when an image of 640 × 480 dots is printed in correspondence with each dot, the size becomes extremely small. In this case, since the tone value is different and the meaning of the resolution itself is different, it is necessary to interpolate between dots and convert the data into printing data. Conventionally, as a method of interpolating dots in such a case, a nearest neighbor interpolation method (near-list neighbor interpolation: hereinafter, referred to as a near-list method) or a cubic convolution interpolation method (cubic convolution interpolation: A method such as the cubic method is known. Also, JP-A-6-2
Japanese Patent No. 25140 discloses a technique in which a dot pattern is prepared in advance so as to have an enlarged form in which the edge is smoothed when the edge is smoothed when the dots are interpolated.

[0004]

The conventional interpolation technique described above has the following problems. Various methods, such as the near-list method and the cubic method, have their advantages and disadvantages, but it is difficult for the user to select it considering the relationship with the interpolation magnification, and it is fixed to either one. Then, there is a possibility that the quality of the interpolation result for a poor image is degraded. In the invention disclosed in Japanese Patent Application Laid-Open No. 6-225140, the interpolation magnification must be fixed because a pattern is prepared in advance, and it is impossible to cope with an arbitrary interpolation magnification. Further, assuming a color image, the number of patterns is enormous and it is difficult to prepare them in advance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and records an image data interpolation apparatus, an image data interpolation method, and an image data interpolation program capable of obtaining an optimum interpolation result for an arbitrary interpolation magnification. The purpose is to provide the media.

[0006]

An image data interpolating apparatus provided by the present invention is an image data interpolating apparatus for increasing the number of constituent pixels at a predetermined interpolation magnification for image data in which an image is represented by dot matrix pixels. An image data acquisition unit for acquiring the image data, an interpolation magnification acquisition unit for acquiring an interpolation magnification of an interpolation process to be performed on the acquired image data, and a constituent pixel of the image data by a predetermined interpolation process. In order to increase the number of pixels, pixel interpolation means is provided which can execute a plurality of interpolation processes by overlapping so as to achieve the obtained interpolation magnification.

According to the present invention, the pixel interpolating means can execute at least a plurality of interpolation processes on the image data. When the image data acquiring means acquires the target image data, The interpolation magnification obtaining means obtains the interpolation magnification of the interpolation processing to be performed on the same image data, and the pixel interpolation means performs a plurality of interpolation processings so as to achieve the obtained interpolation magnification. That is,
This is realized by acquiring the interpolation magnification by itself and performing a plurality of interpolation processes in a superimposed manner.

The interpolation processing differs in characteristics such as the quality of the calculation result and the load of the calculation processing. If a plurality of interpolation processings can be executed, the characteristics can be utilized in each case. Then, if this operation is repeatedly performed, the characteristics can be combined to obtain characteristics different from the existing ones. Therefore, it is possible to provide an image data interpolating apparatus capable of controlling the characteristics of the image data and obtaining an optimal interpolation result by performing the interpolation processing at the time of realizing the predetermined interpolation magnification. As described above, the method of selecting the interpolation processing according to the interpolation magnification need not necessarily be limited to a substantial device, and it can be easily understood that the method also functions as the method. For this reason, the image data interpolation method provided by the present invention, in increasing the number of constituent pixels at a predetermined interpolation magnification for image data representing an image by dot matrix pixels, a step of acquiring the image data, Acquiring the interpolation magnification of the interpolation processing to be performed on the acquired image data; and performing a plurality of interpolation processings so that the plurality of interpolation processings can be performed and the acquired interpolation magnifications are obtained. And increasing the number of constituent pixels of the image data.

That is, there is no difference in that the present invention is not necessarily limited to a substantial device but is also effective as a method. By the way, such an image data interpolation device may exist alone or may be used in a state of being incorporated in a certain device, and the idea of the invention is not limited to this, but includes various aspects. It is a thing. Therefore, if it is software or hardware,
Can be changed. When the software of the image data interpolating device is realized as an example of realizing the idea of the invention, it naturally exists on a recording medium on which such software is recorded, and it cannot be said that the software is used.

As an example, a medium on which an interpolation processing program provided by the present invention is recorded is provided on a computer so as to increase the number of constituent pixels at a predetermined interpolation magnification with respect to image data representing an image by dot matrix pixels. A medium in which an image data interpolation program for causing the interpolation processing to be performed in an overlapping manner is recorded, wherein the step of obtaining the image data, and the step of obtaining an interpolation magnification of the interpolation processing to be performed on the obtained image data, A plurality of interpolation processes can be executed, and a plurality of interpolation processes are superimposed and executed to increase the number of constituent pixels of the image data so that the acquired interpolation magnification is obtained.

Of course, the recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future. Also, the duplication stages of the primary duplicated product, the secondary duplicated product, and the like are equivalent without any question. It should be noted that, although different from the medium of the present invention, the present invention is not limited to the case where the supply is performed using a communication line. Further, even when a part is implemented by software and a part is implemented by hardware, the concept of the present invention is not completely different, and a part is stored on a recording medium and appropriately It may be in a form that can be read.

According to a second aspect of the present invention, in the image data interpolating apparatus according to the first aspect, the pixel interpolating means performs a plurality of interpolation processes while performing a plurality of interpolation processes in an overlapping manner. Only one of the interpolation processes can be executed, and the interpolation process selection means selects the interpolation process to be executed according to the obtained interpolation magnification. That is, as an option of the interpolation process to be executed, an option of executing only one interpolation process among the plurality of interpolation processes is possible together with an option of performing a plurality of interpolation processes in an overlapping manner. An interpolation process to be executed is selected according to the obtained interpolation magnification. According to a third aspect of the present invention, in the image data interpolation apparatus according to the first or second aspect, the pixel interpolating means performs each of the overlapped operations so that the acquired interpolation magnification is obtained. The interpolation magnification of the interpolation processing is determined. That is, since the interpolation processing is performed in an overlapping manner, the obtained image data is obtained by superimposing the respective interpolation magnifications. For this reason, the interpolation magnification is determined in each interpolation processing so that the interpolation magnification finally obtained is obtained. According to a fourth aspect of the present invention, in the image data interpolating apparatus according to the third aspect, when the interpolation magnification exceeds a predetermined magnification, the pixel interpolation means executes the first interpolation processing up to a certain magnification. The insufficient magnification is executed in the second interpolation processing. According to a fifth aspect of the present invention, in the image data interpolating apparatus according to the third aspect, the pixel interpolating means separates the interpolation magnification into a first integral magnification and a second integral magnification. Then, in the first interpolation processing, the interpolation processing is executed at the first magnification, and in the second interpolation processing, the interpolation processing is executed at the second magnification.

According to a sixth aspect of the present invention, in the image data interpolating apparatus according to the third aspect, the interpolation magnification obtaining means detects a resolution at the time of printing, and the pixel interpolating means detects the resolution at the time of printing. The interpolation magnification of the first interpolation processing and the interpolation magnification of the second interpolation processing are determined according to the interpolation magnification based on. Further, in the invention according to claim 7, in the image data interpolation apparatus according to claim 6, the pixel interpolation means sets the first interpolation magnification to a predetermined integral number based on the detected resolution. Is set to be an integer multiple lower than the resolution of, and subsequently, the shortage is set as the second interpolation magnification.

According to an eighth aspect of the present invention, in the image data interpolating apparatus according to any one of the first to seventh aspects, the pixel interpolating means includes an image of an existing constituent pixel in the previous interpolation processing. In addition to performing relatively advanced arithmetic processing on the data to generate the image data of the interpolated pixels, in the subsequent interpolation processing, the image data of the interpolated pixels is subjected to relatively simple arithmetic processing on the image data of the existing constituent pixels. Generate

Of course, these inventions are not necessarily limited to a substantial device, and there is no difference that the invention is effective as a method. It is also possible to be software, in which case it naturally exists on a recording medium on which such software is recorded, and it cannot be said that it is used.

In the present invention, the image data is an image represented by pixels in a dot matrix. Any image data may be represented by data for each pixel. The image data may be a color image or a monochrome image. You may. Also,
The gradation values may be two gradation values or multiple gradation values. The image data obtaining means obtains the image data, and may be any as long as it holds the target image data when the pixel interpolating means performs the interpolation processing for increasing the number of constituent pixels. Therefore, the acquisition method is not particularly limited, and various methods can be adopted. For example, the information may be obtained from an external device via an interface, or may be an image capturing device provided with an image capturing unit. Alternatively, a computer graphics application may be executed to input from a mouse or a keyboard.

The pixel interpolating means may be any one which can execute a plurality of interpolation processes in an overlapped manner, and may be any one which has a plurality of interpolation processes having substantially different interpolation processing results as options. In addition, at least two or more interpolation processes are required since the interpolation processes are performed in an overlapping manner. However, two or more interpolation processes out of the three or more interpolation processes may be performed in a overlapping manner.

On the other hand, the interpolation magnification of each interpolation process is determined such that the final interpolation magnification matches the interpolation magnification acquired by the interpolation magnification acquisition means. As an example, when the interpolation magnification exceeds a fixed magnification, it is possible to execute a single interpolation processing up to the same constant magnification and to execute the insufficient magnification by another interpolation processing. For example, when the interpolation result exceeds the allowable limit, the interpolation result is good, but when the interpolation magnification is large, the interpolation process that increases the calculation amount is performed first. Will be applied later.

In this manner, when the interpolation magnification is increased, the shortage is compensated for by a different interpolation processing. Therefore, if the interpolation processing to be compensated is set to a small amount of calculation, the calculation can be performed even if the interpolation magnification is increased. A sharp increase in the throughput can be avoided. Further, as another example, when the interpolation magnification exceeds a certain magnification, the pixel interpolation means may execute another interpolation processing up to a predetermined magnification, and the insufficient magnification may be executed by the one interpolation processing.

In this case, one interpolation process is basically executed, but the interpolation process is supplemented by another interpolation process in advance until a certain magnification is exceeded. Therefore, when the interpolation magnification is increased although the amount of calculation is small, the interpolation process that the interpolation result is not good is mainly used. An interpolation process that does not exist is performed first.

In this way, when the interpolation result is not good when the interpolation processing is mainly performed at a high magnification, the interpolation processing with high precision is performed in advance to increase the interpolation magnification. Can be avoided from sharply decreasing the interpolation result. The method of obtaining the interpolation magnification is not uniform, and various methods can be adopted. As an example, the image data obtaining unit obtains a magnification specified when obtaining the image data, or based on a ratio between the image data obtained by the image data obtaining unit and the size of the image data to be interpolated. To get the magnification.

In the former case, in a situation where an interpolation magnification is designated as the image data acquiring means acquires the image data, the interpolation magnification acquiring means acquires the designated magnification. That is, when the interpolation magnification itself is designated, the magnification is used. On the other hand, the interpolation factor is not always specified as the interpolation factor. In the latter case, the interpolation factor is not specified. Is calculated by calculating a ratio between the size of the image data and the size of the image data after the interpolation. If the information required for interpolation is notified of the image size after interpolation, etc.,
This is because if the ratio with the image size of the interpolation source is known, the interpolation magnification can be calculated.

In this way, in the former case, the specified interpolation magnification is obtained, so that the processing is facilitated. In the latter case, even if the interpolation magnification is not specified, the processing is performed based on the size of the image data before and after interpolation. Thus, the interpolation magnification can be easily obtained. As described above, it is necessary to interpolate at an arbitrary magnification in the interpolation process. Therefore, the processing amount is reduced. Therefore, when performing a plurality of interpolation processes, it is significant to divide the process into an integer multiple interpolation process and the remaining interpolation processes. On the other hand, if the interpolation magnification is such that the interpolation processing is divided into the integral multiple interpolation processing and the remaining interpolation processing, it cannot be said that the image quality is improved to match the interpolation processing. This is due to the characteristics of a printing apparatus that performs printing in a low gradation expression as to whether or not to add dots when printing with dots of a recording agent such as recording ink. For this reason, in addition to the interpolation processing suitable for improving the characteristics, it is meaningful to perform the interpolation processing from another viewpoint repeatedly.

According to this configuration, the interpolation processing suitable for the improvement of the interpolation result and the interpolation processing not suitable for the improvement of the interpolation result are performed in accordance with the characteristics of the printing apparatus so that the optimum interpolation result can be printed. An interpolator can be provided. In the pixel interpolating means, various changes can be made to the specific mode of separating the interpolation magnification depending on the execution order of the interpolation processing and the like. As an example, the interpolation processing is performed at the first magnification so as to be lower than the resolution of the first threshold based on a predetermined integer fraction of the recording resolution of the printing apparatus, and then the second processing is performed. The interpolation processing is performed at the magnification of to match the recording resolution of the printing apparatus.

In this case as well, the interpolation processing is first performed at the first magnification that is an integral multiple, and the interpolation processing is performed at the second magnification in addition to the interpolation processing.
At this time, the resolution subjected to the interpolation processing at the first magnification is lower than a resolution of an integral fraction of the recording resolution of the printing apparatus, and the second magnification is a remaining magnification but a reciprocal greater than or equal to the reciprocal of this integer. Becomes Then, after interpolating pixels between existing pixels in the first integral multiple processing, one or more pixels are interpolated between the pixels. This is an interpolation process of 4 times or more. However, at this magnification, the improvement of the image quality by the interpolation process is close to the limit due to the characteristics of the printing apparatus, and a plurality of interpolation processes can be executed to balance the throughput. become able to.

To balance the throughput,
Resolution of 180 dpi to 480 dpi at the above first magnification
And the resolution can be made to match the recording resolution of the printing apparatus at the second magnification. Empirically, when the resolution of the printing apparatus is 720 dpi and the resolution of the original image data is 240 dpi, the interpolation processing at twice the minimum multiple becomes 480 dpi.
Even if high-precision interpolation processing is performed to obtain a higher resolution, the image quality cannot be improved. On the other hand, since only copying that does not require arithmetic processing is executed thereafter, it is necessary to obtain a certain resolution in the first high-precision interpolation processing. In this case, the allowable range needs to be about 180 dpi. , It is possible to realize an interpolation process of an integral multiple up to about 240 dpi, and at least 180 dpi
In order to obtain a resolution of about pi, it is necessary to interpolate the resolution of the first stage in the range of 180 dpi to 480 dpi.

By the way, when the precision in printing increases, the burden of the interpolation magnification performed by the high-precision calculation method increases, and the image quality is improved by increasing the burden of the interpolation by the high-precision calculation method. As a result, even if the remaining burden magnification is interpolated by a low-precision calculation method, the reversal of the image quality hardly occurs. In other words, when the definition at the time of printing increases, the definition at the time of transferring the image data from the calculation method with high precision to the calculation method with low accuracy affects the image quality. As the degree increases, the burden ratio of highly accurate calculation methods is increased.

According to this configuration, when the printing precision is increased, the load ratio of the interpolation magnification performed by the high-precision calculation method is increased. As the image quality is improved by increasing the image quality, it is possible to make it difficult to reverse the image quality even if the remaining burden ratio is interpolated by a low-precision calculation method. The pixel interpolating means here may be any one that can perform the interpolation processing with a high-precision calculation method and a low-precision calculation method, but this is not limited to the two calculation methods. Further, whether the calculation method is a high-precision calculation method or a low-precision calculation method is relative, and there is no need to have a reference value.

The burden magnification mentioned here is not necessarily the ratio of the interpolation magnification required to be performed by a high-precision calculation method to the interpolation magnification required to be performed by a low-precision calculation method. Therefore, the interpolation magnification itself, which is to be performed by a highly accurate calculation method, may gradually decrease. The fact that the burden magnification increases while the interpolation magnification gradually decreases means that the ratio of the interpolation magnification increases when the burden magnification is not changed in this way. Means that you can.

As an example, interpolation is performed using a high-precision calculation method until the resolution exceeds a switching resolution that is a fixed resolution, and interpolation is performed using a low-precision calculation method until the remaining resolution is reached.
If the definition at the time of printing is high, the switching resolution is increased. Now, assuming that the definition at the time of printing is low, the switching resolution set in this case is low, and the high-precision calculation method performs interpolation at an interpolation magnification exceeding the switching resolution. However, when the definition at the time of printing increases, the switching resolution also increases. In such a case, interpolation is performed to a point exceeding the switching resolution by a highly accurate calculation method, so that the interpolation magnification increases. In this sense, it can be said that the burden magnification increases.

In this way, the burden magnification changes substantially only by changing the switching resolution, and the adjustment is facilitated.

[0032]

As described above, the present invention provides an image data interpolating apparatus, an image data interpolating method, and an image data interpolating method capable of obtaining an optimal interpolation result by combining and executing a plurality of interpolation processes. A medium in which an image data interpolation program is recorded can be provided. Furthermore, in the inventions according to the second, tenth, and eighteenth aspects, the interpolation processing that is performed in an overlapping manner can be performed as a single interpolation processing, and the range of options can be expanded. Further, in the invention according to claims 3, 11 and 19, the interpolation magnification to be realized in each interpolation process can be efficiently obtained.

Further, in the invention according to claims 4, 12 and 20, when the interpolation magnification exceeds a predetermined magnification, the first interpolation processing is executed up to a certain magnification, and the insufficient magnification is determined by the second interpolation processing. By executing, efficient interpolation processing can be realized. Further, in the inventions according to claims 5, 13 and 21, the interpolation magnification is separated into a first magnification of an integer magnification and a remaining second magnification, and interpolation processing with a large amount of computation is performed at an integer magnification. Since the processing is executed, the total amount of arithmetic processing can be reduced.

Further, in the invention according to claims 6, 14 and 22, the interpolation magnification for the first interpolation processing and the interpolation magnification for the second interpolation processing are determined from the interpolation magnification based on the resolution at the time of printing. Since the determination is made, the interpolation processing can be executed efficiently with simple processing. Claims 7, 15, 2
In the invention according to the third aspect, the first interpolation magnification is set to an integral multiple that is lower than a resolution of a predetermined integer with respect to the detected resolution, and the second interpolation magnification is set to a shortage. Is set, so that a so-called reversal phenomenon can be suppressed.

Furthermore, in the inventions according to claims 8, 16 and 24, advanced arithmetic processing is performed first, and arithmetic processing is performed later to generate image data of interpolated pixels, thereby reducing the amount of arithmetic processing as a whole. Can be done.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of an image data interpolation device according to the present invention. Assuming digital processing, an image is represented by pixels in a dot matrix, and image data is composed of a group of data representing each pixel. In a system that performs processing in units of pixels, the image is scaled up or down in units of pixels. The present image data interpolating apparatus performs such an enlarging process on a pixel basis. Is performed. Here, the pixel interpolation unit C2 can execute a plurality of interpolation processes as the interpolation process. When the interpolation magnification acquisition unit C3 acquires the interpolation magnification for the image data, the interpolation processing selection unit C4 sets the interpolation magnification to the interpolation magnification. Correspondingly, an interpolation process capable of obtaining an optimal interpolation result is selected and executed by the pixel interpolation means C2.

Next, a specific configuration for realizing these will be described. In the present embodiment, the computer system 10 is employed as an example of hardware for realizing such an image data interpolation device. FIG. 2 is a block diagram showing the computer system 10. The computer system 10 includes a scanner 11a, a digital still camera 11b, and a video camera 11c as image input devices, and is connected to a computer main body 12. Each input device is capable of generating image data expressing an image by dot matrix pixels and outputting the image data to the computer main unit 12. Here, the image data is displayed in 256 gradations in three primary colors of RGB. , About 16.7 million colors can be expressed.

A floppy disk drive 13a, a hard disk 13b, and a CD-ROM drive 13c as external auxiliary storage devices are connected to the computer body 12, and main programs related to the system are recorded on the hard disk 13b. Necessary programs and the like can be read from a floppy disk or a CD-ROM as needed. The computer body 1
A modem 14a is connected as a communication device for connecting 2 to an external network or the like. The modem 14a is connected to the external network via the public communication line, and software and data can be downloaded and introduced.
In this example, the modem 14a accesses the outside through a telephone line. However, a configuration in which a network is accessed through a LAN adapter is also possible. In addition, a keyboard 15a and a mouse 15b are connected for operating the computer body 12.

Further, a display 17a and a color printer 17b are provided as image output devices.
The display 17a has a display area of 800 pixels in the horizontal direction and 600 pixels in the vertical direction, and each pixel can display the above-described 16.7 million colors. Of course, this resolution is only an example, 640x48
0 pixels, 1024 x 768 pixels,
It can be changed as appropriate.

The color printer 17b is an ink jet printer, and is capable of printing an image with dots on printing paper as a recording medium using four color inks of CMYK. The image density can be printed at a high density such as 360 × 360 DPI or 720 × 720 DPI, but the gradation table is expressed in two gradations such as whether or not to apply color ink. On the other hand, a predetermined program is executed in the computer main body 12 in order to display or output an image while inputting an image using such an image input device.
Among them, an operating system (OS) 12a is operating as a basic program, and the operating system 12a has a display driver (DSP DR) for performing display on the display 17a.
V) 12b and a printer driver (PRT DRV) 12c for causing the color printer 17b to perform print output are incorporated. These drivers 12b and 12c depend on the model of the display 17a and the color printer 17b, and can be additionally changed to the operating system 12a according to each model. Further, depending on the model, additional functions beyond the standard processing can be realized. That is, it is possible to realize various additional processes within an allowable range while maintaining a common processing system on the standard system of the operating system 12a.

Of course, the premise of executing such a program is that the CPU 12e
, A RAM 12f, a ROM 12g, an I / O 12h, and the like.
While using M12f as a temporary work area, setting storage area, or program area,
The basic program written in 12g is appropriately executed, and I
/ O12h, which controls external devices and internal devices connected thereto.

Here, the application 12d is executed on the operating system 12a as a basic program. The processing contents of the application 12d are various, and monitor the operation of the keyboard 15a and the mouse 15b as operation devices, and when operated, appropriately control various external devices to execute corresponding arithmetic processing and the like. Further, the processing result is displayed on the display 17a or output to the color printer 17b.

In the computer system 10, image data is acquired by a scanner 11a or the like, which is an image input device, and predetermined image processing is executed by an application 12d. It is possible to In this case, focusing on the correspondence between pixels, if the pixel density of the color printer 17b and the pixel density of the scanner 11a match, the size of the scanned original image matches the size of the printed image.
If there is a difference between the two, the size of the image will be different.
In many cases, the pixel density of the scanner 11a is similar to the pixel density of the color printer 17b. However, the pixel density of the color printer 17b whose pixel density is improved for higher image quality is higher than that of a general image input device. It is often higher than the pixel density. In particular, the display 17a
The display density is higher in each stage as compared with the display density described above, and if the display on the display 17a is made to correspond to each pixel and printed, an extremely small image may result.

For this reason, the operating system 12
Resolution conversion is performed in order to eliminate the difference in the actual pixel density of each device while determining the reference pixel density in a. For example, if the resolution of the display 17a is 72D
When it is assumed to be a PI, the operating system 1
If 2D is based on 360 DPI, the display driver 12b performs resolution conversion between the two. In a similar situation, the resolution of the color printer 17b is 72
If it is 0 DPI, the printer driver 12c performs resolution conversion.

Since the resolution conversion corresponds to a process for increasing the number of constituent pixels in the image data, it corresponds to an interpolation process.
c implements interpolation as one of its functions. Here, the display driver 12b and the printer driver 12c execute not only the above-described pixel interpolating means C2 but also the interpolation magnification obtaining means C3 and the interpolation processing selecting means C4 as described below so that the image quality is not deteriorated by the resolution conversion. ing. The display driver 12b
The printer driver 12c is stored in the hard disk 13b, and is read and operated by the computer body 12 at the time of startup. At the time of introduction, the program is recorded on a medium such as a CD-ROM or a floppy disk and installed. Therefore, these media constitute a medium on which the image data interpolation program is recorded.

In this embodiment, the image data interpolation device is realized as the computer system 10,
Such a computer system is not necessarily required, and any system that requires interpolation processing for similar image data may be used. For example, as shown in FIG. 3, a digital still camera 11b1 incorporates an image data interpolating device for performing interpolation processing, and displays the image data on the display 17a1 using the interpolated image data.
A system for printing on 7b1 may be used. As shown in FIG. 4, in a color printer 17b2 that inputs and prints image data without going through a computer system, image data input via a scanner 11a2, a digital still camera 11b2, a modem 14a2, or the like is automatically processed. It is also possible to adopt a configuration in which resolution conversion is performed and print processing is performed.

In addition, a color facsimile machine 18a as shown in FIG. 5 and a color copier 1 as shown in FIG.
It is naturally applicable to various devices that handle image data such as 8b. FIGS. 7 and 8 show a software flow relating to the resolution conversion executed by the printer driver 12c described above. Here, the former shows a general-purpose flow, and the latter shows a specific flow of the present embodiment.

In step ST102, original image data is input. When an image is read from the scanner 11a by the application 12d and subjected to predetermined image processing and then subjected to print processing, print data of a predetermined resolution is transferred to the printer driver 12c via the operating system 12a. Applicable. Of course, the image may be read by the scanner 11a.
This processing is an image data acquisition step when viewed as software, but various steps executed by the computer including the image data acquisition step are understood as not directly including the operating system 12a itself or hardware. can do. On the other hand, if it is considered that the image data acquiring unit C1 is organically integrated with hardware such as a CPU,
Corresponds to.

Step ST104 is a process for obtaining an interpolation magnification for the read image data. Details of the interpolation magnification obtaining process will be described later. Step ST10
In step 8, an optimal interpolation process for the image data is selected in accordance with the obtained interpolation magnification, and steps ST110 and ST11 are performed.
2. One of the interpolation processes 1 to N in ST114 is executed. Therefore, step ST104 corresponds to an interpolation magnification obtaining step, and step ST11 is performed.
Each of the interpolation processes 1 to N shown in 0, ST112, and ST114 specifically corresponds to an image interpolation step. Step ST108 corresponds to an interpolation processing selection step because the interpolation processing is selected based on the interpolation magnification.

Of course, if these are considered to be organically integrated with hardware such as a CPU, they constitute an image interpolation means C2, an interpolation magnification acquisition means C3 and an interpolation processing selection means C4. When the interpolation processing is completed, the image data interpolated in step ST120 is output. In the case of the printer driver 12c, print data cannot be obtained only by resolution conversion, but requires color conversion or halftone processing. Therefore, outputting the image data here means transferring the data to the next stage.

Next, more specific processing for the above-described general-purpose flow will be described. Step ST2
In step 02, original image data is input in the same manner as in step ST102, and in step ST204, an interpolated image data size is input in order to obtain an interpolation magnification. The input of the interpolated image data size is performed in step ST1 described above.
This is for acquiring the interpolation magnification corresponding to step 04. Here, the interpolation magnification acquisition means will be described. FIG. 9 shows an example in which the printer driver 12c acquires an interpolation magnification based on information obtained from the operating system 12a. As a first example, operating system 12a
May directly specify the interpolation magnification for the printer driver 12c. In this case, the interpolation magnification is used. As a second example, the operating system 12a
May specify the size of the image to be printed in pixel units. In this case, the interpolation magnification is calculated based on the magnitude. For example, if the vertical and horizontal dimensions of the original image data are Ws × Hs pixels and the vertical and horizontal dimensions of the interpolated image data are Wd × Hd pixels, the interpolation magnification is Wd / Ws (or Hd) on the assumption that the aspect ratio is not changed.
d / Hs).

As a third example, there is a case where a resolution managed by the operating system 12a is specified. In this case, the printer driver 12c calculates the ratio based on the resolution of the color printer and obtains the interpolation magnification. For example, if the resolution managed by the operating system 12a is 360 DPI and the resolution of the color printer is 720 DPI, the interpolation magnification is twice. In the present embodiment, it is assumed that the interpolation magnification is obtained based on the second example among these, and as described above, the step ST2
In step 04, an interpolation image data size is input.

When the interpolation image data size is input in step ST204 as described above, step ST20
In step ST206, it is determined whether or not the interpolation magnification exceeds 4 times based on the ratio of the size of the original image data input in step ST208.
10 performs an appropriate interpolation process. Here, each method of the interpolation processing executed in the present embodiment will be described. As an interpolation process suitable for non-natural images such as computer graphics and having a very small amount of computation, there is an interpolation process of a near-list method. In the near-list method, as shown in FIG.
The distance between j, Pi + 1j, Pij + 1, Pi + 1j + 1 and the point Puv to be interpolated is obtained, and the data of the closest lattice point is transferred as it is. When this is represented by a general formula, P
uv = Pij where i = [u + 0.5], j = [v +
0.5]. [] Indicates that a Gaussian symbol takes an integer part.

FIG. 11 shows that the number of pixels is set to 3
This shows a situation where interpolation is performed twice at a time. As the pixel to be interpolated, data of the closest pixel among the first four corner pixels is transferred as it is. Therefore, the original image in which black pixels are arranged obliquely with white pixels as a background as shown in FIG. 12 has a relationship in which black pixels are arranged in an oblique direction while being enlarged three times vertically and horizontally as shown in FIG. Is held.
The near-list method has a feature that an edge of an image is held as it is. Therefore, when enlarged, jaggies are noticeable but edges are retained as edges. However,
Since the data to be interpolated is the data of the lattice points themselves, there is little burden in terms of arithmetic processing. On the other hand, in other interpolation processing, the pixel to be interpolated is changed smoothly using data of surrounding pixels. Therefore, while the jaggy becomes inconspicuous, the information of the original image is cut off, and the edge disappears, making it unsuitable for non-natural images such as computer graphics.

On the other hand, as an interpolation process which is suitable for a natural image such as a photograph and has a large amount of calculation processing, there is an interpolation process of a cubic method. As shown in FIG. 14, the cubic method uses data of a total of 16 grid points including not only four grid points surrounding a point Puv to be interpolated but also grid points around one point. When a total of 16 grid points surrounding the interpolation point Puv have respective values, the interpolation point Puv
Is determined by those influences. For example, if an attempt is made to interpolate using a linear expression, weighted addition may be performed in inverse proportion to the distance from the two grid points sandwiching the interpolation point. Focusing on the X-axis direction, the distance from the interpolation point Puv to the above-mentioned 16 grid points is x1, the distance to the left outer grid point is x1, the distance to the left inner grid point is x2, and the right inner While expressing the distance x3 to the grid point and the distance x4 to the right outer grid point,
The degree of influence corresponding to such a distance is represented by a function f (x). Further, when focusing on the Y-axis direction, the distance from the interpolation point Puv to the 16 grid points is y1, the distance from the upper outer grid point to y1, the distance from the upper inner grid point to y2, and the lower inner grid point. Similarly, the degree of influence can be expressed by a function f (y) while expressing the distance y3 to the point and the distance y4 to the lower outer grid point.

The 16 grid points contribute to the interpolation point Puv with the degree of influence according to the distance as described above. The general formula to be accumulated is as follows.

[0057]

(Equation 1) If the degree of influence according to the distance is represented by a third-order convolution function, then f (t) = {sin (πt)} / πt. Note that the above-described distances x1 to x4, y1 to y4
Is calculated as follows using the absolute value of the coordinate value (u, v) of the grid point Puv. x1 = 1+ (u- | u |) y1 = 1+ (v- | v |) x2 = (u- | u |) y2 = (v- | v |) x3 = 1- (u- | u | ) y3 = 1- (v- | v |) x4 = 2- (u- | u |) y4 = 2- (v- | v |)

[0058]

(Equation 2) Becomes The degree of influence f (t) according to the distance, which is called a third-order convolution function, is approximated by the following cubic expression.

[0059]

(Equation 3) The cubic method has a feature that the gradual change gradually proceeds from one grid point to the other grid point, and the degree of the change becomes a so-called cubic function.

FIG. 15 and FIG. 16 show specific examples when interpolation is performed by the cubic method. For ease of understanding, a model in which there is no change in data in the vertical direction and an edge occurs in the horizontal direction will be described.
The number of pixels to be interpolated is three. First, specific numerical values in FIG. 16 will be described. The gradation value of the pixel before interpolation is indicated as “Original” in the left column, and the gradation value “6” is displayed.
4 pixels (P0, P1, P2, P3) are arranged at four points, one pixel (P4) having a gradation value of "128" is interposed, and a gradation value of "1"
Five 92 pixels (P5, P6, P7, P8, P9) are arranged. In this case, the edge is a portion of the pixel having the gradation value “128”.

Here, three pixels (Pn1, Pn1) are located between each pixel.
n2, Pn3), the distance between the interpolated pixels is “0.25”, and the above-described x1 to x4
Is the value in the middle column of the table for each interpolation point. f (x1) to f (x4) are also uniquely calculated corresponding to x1 to x4. For example, x1, x2, x3, and x4 are "1.25" and "0.25", respectively. , "0.75",
When “1.75” is obtained, f (t) corresponding thereto is approximately “−0.14”, “0.89”, “0.3”
0 "and" -0.05 ". X1, x2, x
3, x4 are “1.50”, “0.50”,
When “0.50” and “1.50” are obtained, f (t) corresponding thereto is “−0.125” and “0.62”.
5 "," 0.625 ", and" -0.125 ". In addition, x1, x2, x3, and x4 are each "1.7.
5 "," 0.75 "," 0.25 ", and" 1.25 ", f (t) corresponding thereto is roughly expressed as"-
0.05 "," 0.30 "," 0.89 "," -0.1
4 ". The result of calculating the gradation value of the interpolation point using the above result is shown in the right column of the table, and is shown graphically in FIG. The meaning of this graph will be described later in detail.

Assuming that there is no change in the data in the vertical direction, the calculation is simplified, and only the data (P1, P2, P3, P4) of the four grid points arranged in the horizontal direction are referred to.
Influence degree f according to distance from interpolation point to each grid point
Using (t), it can be calculated as follows. P = P1 ・ f (x1) + P21f (x2) + P3 ・ f (x3) + P4 ・ f (x4) Therefore, when calculating for the interpolation point P21, P21 = 64 * f (1.25) +64 * f (0.25) + 64 * f (0.75) + 128 * f (1.75) = 64 * (-0.14063) + 64 * (0.890625) + 64 * (0.296875) +128 * (-0.04688) = 61

According to the cubic method, since it can be expressed as a cubic function, the quality of the interpolation result can be influenced by adjusting the shape of the curve. As an example of the adjustment, 0 <t <0.5 f (t) =-(8/7) t ** 3- (4/7) t ** 2 + 1 0.5 <t <1 f (t) = (1 -t) (10/7) 1 <t <1.5 f (t) = (8/7) (t-1) ** 3+ (4/7) (t-1) ** 2- (t-1 ) 1.5 <t <2 f (t) = (3/7) (t−2) is called a hybrid bicubic method.

FIG. 17 shows a specific example when interpolation is performed by the hybrid bicubic method, and shows a result obtained by interpolating a model on the same assumption as in the case of the cubic method. FIG. 15 also shows the result of the interpolation processing by the hybrid bicubic method.
The quadratic curve becomes slightly steep, and the entire image becomes sharper. In order to understand the characteristics of the above-described near-list method, cubic method, and hybrid bi-cubic method, a bi-linear interpolation method (bilinear interpolation) will be described.

As shown in FIG. 18, the bilinear method is similar to the cubic method in that it gradually changes as one grid point approaches the other grid point. In that it is linear in that it only depends on That is, four lattice points Pij, Pi + 1j, Pij + 1, Pi + surrounding the point Puv to be interpolated
The area defined by 1j + 1 is divided into four sections by the interpolation point Puv, and the data at the diagonal positions is weighted by the area ratio. When this is expressed by an equation, P = {(i + 1) -u} (j + 1) -v {Pij +
｛(I + 1) -u｝ ｛v-j｝ Pij + 1 + ｛u-i
｝ ｛(J + 1) -v｝ Pi + 1j + ｛u-i
｝ ｛V−j｝ Pi + 1j + 1. Note that i = [u] and j = [v].

The two cubic methods and the bilinear method are common in that they gradually change as one grid point approaches the other grid point. The difference is large when viewed as an image. FIG. 19 is a diagram two-dimensionally showing the difference between the interpolation results in the near-list method, the cubic method, the hybrid bi-cubic method, and the bilinear method in order to facilitate understanding. In the figure, the horizontal axis indicates the position, and the vertical axis indicates the interpolation function. Of course, this interpolation function corresponds to the degree of influence according to the distance described above.
Grid points exist at positions of t = 0, t = 1, and t = 2, and interpolation points are at positions of t = 0 to 1.

In the case of the bilinear method, between two adjacent points (t
= 0 to 1), the boundary is smoothed because it changes only linearly, and the impression of the screen is blurred. That is, unlike the smoothing of the corners, if the boundary is smoothed, the contour which should be originally in computer graphics disappears, and the focus becomes weak in a photograph. On the other hand, in the cubic, not only is the point between two adjacent points (t = 0 to 1) drawn gradually like a mountain-shaped convex, but also the outer side (t = 1 to 2) between the two points is lower. It has the effect of pushing down. That is, a certain edge portion is changed so as to have a large difference in height such that no step is formed, and in a photograph, a favorable effect is obtained in which no step is formed while increasing sharpness. In addition, the hybrid bicubic has an effect of increasing sharpness. Note that the cubic method requires a large amount of arithmetic processing if the interpolation magnification is large and the number of pixels to be interpolated is large.

If emphasis is placed on the image quality, a cubic function like the cubic method is likely to be selected. However, in computer processing, the balance between speed and image quality is large. That is, although the degree of reduction in the processing speed increases with the degree of improvement in the image quality, there is a case where the higher processing speed is preferred even if the image quality is slightly or slightly reduced. On the other hand, it is easier to understand by referring to FIGS. 15, 16 and 17 showing specific numerical values along with the comparison of the interpolation functions as described above. Referring to the example of FIG. 15, a pixel (P3) having a gradation value of “64”, a pixel (P4) having a gradation value of “128”, and a pixel (P5) having a gradation value of “192”, which are original edge portions. )), The simple linear connection method is equivalent to the bilinear method, whereas the cubic method has a specific S-shaped curve, and the hybrid bicubic method. In the figure, the S-shaped curve is steeper. Needless to say, the direction of the S-shaped curve is a direction in which the change in the gradation value of the pixel is steep, and therefore the edge is emphasized. Further, in the regions (P2 to P3, P5 to P6) adjacent to the edge pixels, so-called undershoots and overshoots have occurred. The height difference becomes larger. Therefore, it can be understood that the edge is emphasized by these two factors.

It can be easily understood that whether the image looks sharp depends on the inclination angle of the central portion of the S-shaped curve. In addition, it can be said that the height difference caused by the undershoot and the overshoot on both sides of the edge also has an effect. The flow of the present embodiment shown in FIG. 8 emphasizes the speed. That is, basically, the interpolation processing by the near list method is executed, and the interpolation processing by the hybrid bicubic method is executed as necessary. More specifically, it is determined whether or not the interpolation magnification exceeds 4 times in step ST206, and if not, in step ST208, the interpolation magnification β is Wd /
Assuming that it is Ws, the interpolation processing by the near list method is executed.

However, when the interpolation magnification exceeds 4 times, if the interpolation processing is performed only by the near-list method, jaggies become conspicuous and the image quality is inevitably reduced. For this reason, if it is determined in step ST206 that the interpolation magnification is more than four times, first, the hybrid bicubic method is used to enlarge the data to a predetermined integer multiple, and then repeat the shortfall interpolation by a near-list. Perform by law. Here, the enlargement is performed by the hybrid bicubic method. However, since the interpolation processing is an integral multiple, the amount of calculation processing can be relatively reduced.

Originally, the interpolation processing itself can be executed at an arbitrary magnification in both the hybrid bicubic method and the cubic method. However, if interpolation processing of an integral multiple is accepted, the number of pixels to be interpolated is reduced, and the processing speed can be increased. FIG. 20 shows an example of processing for interpolating twice in the horizontal and vertical directions. If a variable area for the interpolated image data is secured in advance, the image data of the original image will be the image data of the pixel corresponding to the coordinate value multiplied by the integer if the interpolation processing is an integral multiple. In the example shown in the figure, the old coordinate value (0,0) corresponds to the new coordinate value (0,0), the old coordinate value (1,0) corresponds to the new coordinate value (2,0), The old coordinate value (0, 1) corresponds to the new coordinate value (0, 2), and the old coordinate value (1, 1) corresponds to the new coordinate value (2, 2). Therefore, image data is generated only for the remaining coordinate values in accordance with the above-described interpolation processing. In this case, scanning can be performed sequentially with the width direction of the image data as the main scanning direction and the length direction as the sub-scanning direction, or for each block surrounded by four grid points having image data. It is also possible to perform interpolation processing of the internal coordinate values and fill them.

In this way, without increasing the amount of arithmetic processing so much, after performing the integral multiplication by the hybrid bicubic method, the remaining interpolation magnification β = Wd / (α
• Interpolate Ws) using the nearest method. Now, the load of each interpolation process will be described for an example of printing a VGA size (640 × 480) image at a 2L print size. For the size of the original image data, Ws = 640, Hs = 480 (pixels), and the size of the interpolated image data, ie, the 2L print size is 16 cm × 12 cm.
ch × 4.724 inch. Final resolution is 720
Assuming DPI, the size of the interpolated image data indicated in pixel units is Ws = 4535 and Hs = 3401 (pixel). Then, the overall magnification Wd / Ws is 4536 /
640 = 7.0875.

The branch decision in step ST206 is as follows.
The intention is to reduce the interpolation magnification by the near-list method to 4 times or less so that jaggies do not occur. Then, when the overall magnification exceeds four times, an interpolation process by the near-list hybrid bicubic method is executed. In order to execute the hybrid bicubic method of an integral multiple, it is necessary to perform at least double interpolation. Overall magnification Wd
In order to prevent / Ws from exceeding "4 times" and the insufficient magnification in the interpolation at the previous stage not exceeding 4 times, at least a magnification of at least 1/4 of the whole magnification (Wd / Ws) is required. Must be performed by interpolation in. Therefore, α = (Wd / Ws) × １ ／ = Wd / 4Ws. If some margin is added to the interpolation by the near-list method, α = Wd / 5Ws. However, in this case, when the hybrid bicubic method is executed at an integer multiple, the number may be only one, so it is necessary to at least double the hybrid bicubic method. Therefore, it is determined as α = Wd / 5Ws + 1. Of course, fractions will be cut later. Then, the interpolation magnification α according to the hybrid bicubic method is Wd / 5Ws + 1 = 4536 / (5 * 64).
0) + 1 = 2.4175, so α = 2 as an integral part thereof. Then, the interpolation magnification β of the near-list method is β = Wd / αWs = 4536 / (2 * 640) = 3.5
4375.

When all the new coordinate values have been interpolated by one of the interpolation processes, the process proceeds to step ST2.
At 14, the interpolated image data is transferred to the next stage of processing. However, the data amount of the interpolated image data may be extremely large depending on the interpolation magnification, and the memory area available to the printer driver 12c may not be so large in the first place. In such a case, the data may be output separately for each fixed data amount.

As described above, the flow shown in FIG. 8 focuses on the speed aspect. However, a process emphasizing the image quality can be performed, and an example thereof is shown in FIG. The difference between the flow shown in FIG. 21 and the flow shown in FIG.
Is that the interpolation process executed in step (1) is a near-list method or a hybrid bicubic method. The execution of the hybrid bicubic method as described above can be said to be an image quality-oriented process in the sense of improving the interpolation result in a natural image as described above. However, since the burden of the arithmetic processing is large, even if the interpolation magnification is large, if all of them are to be covered, the processing amount becomes very large. For this reason, the interpolation processing is executed by the hybrid bicubic method up to four times, but the interpolation processing beyond that is prevented from increasing rapidly by the near-list method.

In the above example, a plurality of interpolation processes are executed when the interpolation magnification becomes equal to or more than a certain value. However, it is not always necessary to perform the interpolation processes repeatedly.
Different interpolation processing may be prepared for each specific interpolation magnification. As described above, since the curve can be adjusted in the cubic method, a plurality of such adjustment parameters are prepared according to the interpolation magnification, and the interpolation result is changed due to the difference in the parameters of the cubic method as the interpolation processing. It is also possible to do so.

As described above, in the computer system 10 having the scanner 11a and the like as the image input device and the color printer 17b and the like as the image output device, the printer driver 12c inputs the original image data in step ST202, and proceeds to step ST2.
By inputting the size of the interpolated image data in step 04, the interpolation magnification is obtained in step ST206, and the interpolation process using only the near-list method in step ST208 is executed according to the interpolation magnification, or the hybrid bicubic in ST210 is executed. Since the interpolation process of the interpolation method and the interpolation process of the near-list method are performed in an overlapped manner, an optimum interpolation result according to the interpolation magnification can be obtained very easily.

Next, a description will be given of an embodiment in which, when a plurality of interpolation processes are performed in an overlapping manner, the interpolation processes are performed at optimal interpolation magnifications. FIG. 22 is a block diagram showing such an image data interpolation device. In the present image data interpolation apparatus, the image data acquisition means D1 acquires image data, and the interpolation magnification acquisition means D2 acquires an interpolation magnification based on the difference in resolution. The pixel interpolating means D3 performs an interpolation process for increasing the number of constituent pixels of the acquired image data according to the acquired interpolation magnification. Then, the interpolation of the first magnification and the interpolation of the second magnification are performed in an interpolating process different from each other. Here, the printing result of a color image is particularly improved.

The processing result of the application 12d is output as print data to the above-described color printer 17b via the printer driver 12c, and the color printer 17b uses color ink to form dots on printing paper, thereby Print the image you want. FIG. 23 to FIG. 25
1 shows a schematic configuration of a color inkjet printer 21 as an example of such a color printer. The color inkjet printer 21 includes a print head 21a including three print head units, a print head controller 21b that controls the print head 21a, a print head digit moving motor 21c that moves the print head 21a in the digit direction, A paper feed motor 21d for feeding print paper in the row direction, and a print head controller 21b
And print head girder moving motor 21c and paper feed motor 21d
And a printer controller 21e, which is an interface with an external device, and is capable of printing an image while scanning the print head 21a on a recording medium, which is printing paper, according to print data.

FIG. 24 shows a more specific configuration of the print head 21a, and FIG. 25 shows the operation at the time of ink ejection. The print head 21a has a color ink tank 2
Fine line 21a3 from 1a1 to nozzle 21a2
Are formed, and an ink chamber 21a4 is formed at the end portion of the conduit 21a3. This ink chamber 21a4
Is formed of a flexible material, and a piezo element 21a5, which is an electrostrictive element, is provided on the wall. The piezo element 21a5 has a crystal structure that is distorted by applying a voltage and performs high-speed electrical-mechanical energy conversion. The distortion operation of the crystal structure pushes the wall surface of the ink chamber 21a4, and the piezo element 21a5 presses the wall.
Decrease the volume of Then, a predetermined amount of color ink particles is vigorously ejected from the nozzle 21a2 communicating with the ink chamber 21a4. This pump structure is called a micro pump mechanism.

Note that one print head unit is formed with two independent rows of nozzles 21a2, and the nozzles 21a2 of each row are supplied with color ink independently. Therefore, each of the three print head units is provided with two rows of nozzles, and it is possible to use six color inks to the maximum extent. FIG.
In the example shown in FIG. 2, two rows in the left printhead unit are used for black ink, only one row in the middle printhead unit is used for cyan ink, and the left and right printhead units in the right row are used. Two rows are used for magenta ink and yellow ink, respectively.

In the present embodiment, the printing is executed based on the image data obtained by the image input device of the computer system 10 on the premise of the hardware system described above. At this time, when there is a difference between the resolution of the original image data and the resolution of the color printer 17b, the interpolation processing is executed. Here, when the application 12d executes the printing process, the color printer 17
The change in resolution and gradient when print data is output for b will be described. FIG. 28 shows the flow of image data.

The resolution of the original image data represented as a dot matrix pixel is 180 dpi or less and 256
If it is determined that the gradation is to be obtained, first, the pixel interpolation processing in step ST402 is executed to match the resolution with 720 dpi which is the resolution of the color printer 17a. Then, the interpolated image data has 256 gradations at 720 dpi. After that, when the color conversion processing of step ST404 is performed in accordance with the color ink of the color printer 17b, 256 gradations of C are obtained.
The data becomes MYK image data. Finally, halftone processing in step ST406 is performed to obtain two gradations, which is the expression gradation in the color printer 17b.

In this example, the pixel interpolation processing in step ST402 constitutes the image data interpolation apparatus of the present invention. A series of image data processing including this step is performed by the printer driver 12c. Therefore, it can be said that the printer driver 12c constitutes the above-described image data acquisition unit D1, interpolation magnification acquisition unit D2, and pixel interpolation unit D3. This printer driver 12c
Are also stored in the hard disk 13b, and are read and operated by the computer main body 12 at the time of startup. At the time of introduction, it is recorded on a medium such as a CD-ROM or a floppy disk and installed.
Therefore, these media constitute a medium on which the image data interpolation program is recorded.

As described above, in the present embodiment, the image data interpolation device is realized as the computer system 10 and is realized in the process of outputting print data to the color printer 17b. The invention is not limited to the ink jet type color printer 21. The color printer 21 is of an ink jet type employing a micro pump mechanism, but it is also possible to employ a printer other than the micro pump mechanism.

For example, as shown in FIG.
A heater 21a8 is provided on the wall surface of the conduit 21a7 near 6 and heated by the heater 21a8 to generate bubbles.
A bubble jet type pump mechanism that discharges color ink at that pressure has also been put to practical use. FIG. 27 shows a schematic structure of a main part of a so-called electrophotographic color printer 22 as another mechanism. A charging device 22b, an exposure device 22c, a developing device 22d, and a transfer device 2
2e and the rotating drum 22 by the charging device 22b.
After the peripheral surface of a is uniformly charged, the charging of the image portion is removed by the exposure device 22c, the toner is attached to the uncharged portion by the developing device 22d, and the toner is used as a recording medium by the transfer device 22e. Transfer to paper. After that, the toner is melted by passing between the heater 22f and the roller 22g to be fixed on the paper. Since these are combined to perform printing with one color toner, a total of four colors are separately provided.

That is, the specific configuration of the printing method is not particularly limited. In addition, various changes are possible not only in the application range of such an individual printing method but also in the application mode. Next, a specific process for realizing the present image data interpolation apparatus will be described. FIG. 29 shows more detailed contents of the pixel interpolation processing. In step ST502, original image data is input.
For example, when an image is read from the scanner 11a by the application 12d and print processing is performed after performing predetermined image processing, print data of a predetermined resolution is transferred to the printer driver 12c via the operating system 12a. Stages apply. Of course,
An image may be read by the scanner 11a. In any case, the processing is an image data acquisition step when viewed as software.
If it is considered to be organically integrated with hardware such as a PU, it corresponds to the image data acquisition means D1.

Step ST504 is a process for obtaining the interpolation magnification for the read image data. In this example, the interpolation image data size is input to obtain the interpolation magnification. There are various methods for obtaining the interpolation magnification specifically as described above. However, it is assumed that the interpolation magnification is obtained based on the second example shown in FIG.
In step 04, an interpolation image data size is input. Of course, the processing in step ST504 corresponds to an interpolation magnification obtaining step, and the processing which is organically integrated with the hardware constitutes the interpolation magnification obtaining means D2.

After inputting the interpolated image data size in step ST504, it is determined in step ST506 whether or not the resolution of the original image data is less than 180 dpi. Execute. The reason why 180 dpi is used as a reference for the threshold value is due to the above-described printing characteristics of the color printer 17b, and is as follows. As described above, the resolution of the color printer 17b is 7
20 dpi, very high resolution,
440 dpi has also been developed. However, when outputting an interpolated image with a high-resolution printer,
It cannot always be said that the higher the resolution of the printer, the higher the image quality.

If the resolution of the original image data is not so high, the image will be reduced if it is printed in dot units without matching the resolution. Therefore, printing is usually performed with the same resolution. If the original resolution is low, pixels that were not included in the original image data are interpolated and increased, so some kind of interpolation processing is required. As the interpolation processing, various types described above can be adopted, but each has its own characteristics. If this is expressed simply, it can be classified into one in which the image data of the closest pixel is copied as it is, and one in which an interpolation pixel is generated by performing some arithmetic processing. Intuitively, the latter can increase the processing amount and improve the image quality,
There is a limit.

Empirically speaking, in the color printer 17b having a resolution of 720 dpi, when the image data having a resolution lower than 360 dpi is made to coincide with the resolution of 720 dpi, the method of the interpolation processing has no significant effect. This can be said to be a limit derived from the relationship between human visibility and the printing method in the color printer 17b.
However, if the resolution is 360 dpi or less, the change in image quality is visible. For example, the result of interpolation processing of image data having a resolution of 180 dpi by the former method and the result of interpolation processing by the latter method can be determined to be higher in image quality. Therefore, it is significant to select an interpolation process having different characteristics for the interpolation process at 360 dpi or less and the interpolation process at a resolution higher than 360 dpi.

Then, assuming that an interpolation process requiring an arithmetic process is executed for the interpolation process executed at 360 dpi or less, it cannot be said that it is best to perform the interpolation process up to 360 dpi. Since such interpolation processing requires a large amount of arithmetic processing for each pixel that increases, in the worst case, when trying to perform interpolation processing at an arbitrary magnification, all pixels of the image data after interpolation must be calculated by calculation, The calculation time becomes long.

As shown in FIG. 20, even if the interpolation processing itself can be executed at an arbitrary magnification, if only the integral multiple interpolation processing is accepted, the number of pixels to be calculated is reduced, and the processing speed is increased. Can be achieved. Of course, it is also possible to sequentially scan the image data in the main scanning direction in the width direction and the length direction in the sub-scanning direction. It is also possible to perform interpolation processing of the coordinate values of and fill in them.

Therefore, at 360 dpi or less, it can be said that it is best to interpolate by an integral multiple in the interpolation processing for executing the arithmetic processing, and to interpolate the remaining deficiency by the interpolation processing with the smallest possible processing amount. It should be noted that such a threshold value is affected by the final print resolution or a reproducible gradation, so that there are some aspects that cannot be definitely determined. In the present embodiment, when it is determined in step ST506 that the resolution of the original image data is less than 180 dpi, the interpolation processing in step ST508 is executed. First, the interpolation processing is performed at an integer multiple of 180 to 360 dpi. The interpolation magnification is derived as a first magnification, and the first magnification is interpolated by the interpolation processing of the hybrid bicubic method. Then, the shortage after the integer multiple is used as the second magnification and interpolated by the nearestist interpolation process.

Taking the characteristics of the respective interpolation processes into consideration and applying it to the flow of the present embodiment shown in FIG. 29, the number of pixels to be interpolated is an integer multiple that requires a relatively small amount of computational processing at first. Interpolation processing is performed, and then interpolation processing that requires a large number of pixels to be interpolated but requires little arithmetic processing is performed, which is the best method.
If the original image data is 150 dpi, 360d
The interpolation magnification of an integral multiple below “pi” is “2” times, and the resolution becomes 300 dpi by the interpolation processing by the hybrid bicubic method. Therefore, the shortage magnification is (720/300 =) “2.4” times, and this is used as the second magnification to perform the interpolation processing by the near-list method. Of course, in this way, the first magnification is determined and the corresponding interpolation processing is executed, and the insufficient second magnification is determined and the corresponding interpolation processing is executed in step ST508.
Is the image interpolation step, and the CPU
Assuming that the image interpolation means D3 is organically integrated with hardware such as the image interpolation means D3.

In the example shown in FIG. 29, the first magnification is determined on the assumption that the color printer 17b as a printing device is 720 dpi. That is, first 18
Interpolation processing of an integral multiple is performed so as to be in the range of 0 to 360 dpi. However, the resolution of the printing device is 60
When the resolution becomes lower, such as 0 dpi, the upper limit of the range is set to be equal to or less than an integral number of the resolution. Therefore, in this example, the upper limit is set to 300 dpi.

In the example shown in FIG. 30, step ST608 is performed.
When determining the first magnification at, this range is 180 dp
i to 300 dpi. For example, if the original image data is 72
Assuming that the input is made in dpi, the interpolation magnification of an integral multiple at 300 dpi or less is "4", and the interpolation is performed up to 288 dpi by the hybrid bicubic interpolation process. And the remaining about (600/288 =)
The interpolation processing is performed by the nearest method using “2.1” times as the second magnification.

Note that step ST506 and step ST506
If it is determined in step 606 that the resolution of the original image data exceeds 180 dpi, the method of the interpolation processing that matches the resolution of the printing apparatus and the improvement in image quality are not necessarily in proportion as described above. In this example, the interpolation processing is performed by a near-list method with a simple processing. Then, when the interpolation processing is completed, the image data interpolated in steps ST514 and ST614 is output. However, after this, step ST4
Since the color conversion process of step 04 and the halftone process of step ST406 are performed, outputting the image data here means transferring the data to the next stage.

As described above, the computer system 10 having the ink jet type color printer 17b and the like can be used.
In the above, when the resolution of the color printer 17b and the resolution of the original image data do not match, the interpolation processing is executed. Since the second interpolation factor is divided into the second magnification and the different interpolation processes are performed in each, the interpolation process of the integral multiple is performed by the hybrid bicubic method and the shortage interpolation process is repeated by the nearlist method. This makes it possible to achieve an optimal balance between the amount of interpolation processing and the improvement in image quality.

Next, a description will be given of an embodiment in which the magnification for switching the interpolation process is changed when a plurality of interpolation processes are executed. This is particularly due to the human visual recognition performance, and it is possible to increase the efficiency of the calculation by changing the switching magnification. FIG. 31 is a block diagram showing such an image data interpolation device. The present image data interpolation apparatus performs interpolation processing of constituent pixels in consideration of the human visual recognition performance having a delicate correlation. When the toned image data is obtained, the pixel interpolation means E2
Is interpolated by a high-precision operation method and then interpolated by a low-precision operation method. When the pixel interpolating means E2 performs an interpolation process based on the image data, the definition at the time of printing is determined by the fineness detecting means E3. Is detected. The interpolation magnification adjusting means E4 calculates the burden ratio in the pixel interpolating means E2 based on the fineness detected by the fineness detecting means E3. In this case, the higher the definition, the higher the accuracy of the calculation method. The interpolation magnification is adjusted so as to increase the burden magnification assigned to. The pixel interpolating means E2 interpolates according to the interpolation magnification adjusted in this way with a high-precision arithmetic method and then performs interpolation with a low-accuracy arithmetic method, and the print data output means E5 converts the interpolated image data into an interpolated image data. The print data is converted into predetermined print data based on the print data and output.

Here, the change in resolution and gradient when print data is output to the color printer 17b when the application 12d executes the printing process will be described. FIG. 32 shows the flow of image data. Application 12d is operating system 12a
A print request is issued to the
The image data of 256 gradations is transferred. Then, the operating system 12a transfers the output size and the image data to the printer driver 12c, and the printer driver 12c performs data input / output with the operating system 12a to input a print option. Here, the operating system 12a outputs the operation result of the keyboard 15a and the mouse 15b to the printer driver 12c while displaying on the display 17a via the display driver 12b, and the printer driver 12c reflects the operation result as a print option. Generate print data. Usually, this print data is CMY
K2 gradation is output from the hardware port to the color printer 17b via the operating system 12a.

Needless to say, in this example, the printer driver 12c, together with the image data acquiring means E1, the pixel interpolating means E2, and the print data output means E5, correspond to the processing contents to be described later, This constitutes means E4. Next, a description will be given based on the contents of the printing process shown in FIG. In step ST702, image data is input. For example, application 12
When an image is read from the scanner 11a by d and a predetermined image processing is performed and then a printing process is performed, image data having a predetermined resolution is transferred to the printer driver 12c via the operating system 12a. I do. Of course, the image may be read by the scanner 11a. In any case, the process is an image data acquisition step, and the image is considered to be organically integrated with hardware such as a CPU. This corresponds to the data acquisition means E1.

Step ST702 is a process for selecting an output resolution in order to obtain the definition at the time of printing. When the print processing is executed by the application 12d, assuming that the operating system 12a provides a GUI environment, a window for a print operation is displayed as shown in FIG. Various parameters can be adopted as parameters input here, but as an example,
"Copies (of print)", "Start page", "End page"
and so on. As the operation instruction buttons, a "printer setting" button is prepared in addition to the "OK" button and the "cancel" button.

When "Printer setting" is instructed,
A window is displayed as shown in FIG. In this window display, various settings according to the function of each printer are prepared. In this example, “(printing) resolution” is used.
, One of "360 dpi" and "720 dpi" can be selected. Also, “A4” or “B5” as “paper”,
"Vertical" or "horizontal" can be selected as the "print direction". In the present embodiment, the selection of “resolution” has an important meaning, and in step ST704, if the resolution has already been selected, the setting file is referred to and read out. Is changed, the resolution after the change is read as the output resolution. In any case, the selection process is a definition detection step. If it is considered that the selection process is organically integrated with hardware such as a CPU, the definition process E3 is configured. In the present embodiment, the resolution selected by software based on such a window display is detected with fineness. However, the operation of selecting the resolution is not limited to this, and the resolution is not limited to software. It can be changed as appropriate in terms of hardware. The software may display something other than the window display, and instead of letting you select the resolution directly, indirectly like the speed of printing speed (because it is slower if it is fine, it will be faster if it is coarser) It may be something to select.

In the processing of the next step ST706, the processing branches according to the selected resolution, and the processing proceeds to step ST706.
In steps 708 and ST710, processing for setting the switching resolution is performed. Before describing the switching resolution in detail, the flow of the pixel interpolation process will be described. In step ST708, the switching resolution is set to 180 dpi,
At 710, the switching resolution is set to 240 dpi. Then, in step ST712, the interpolation magnification is obtained, the first-stage interpolation magnification is obtained from the relationship between the interpolation magnification and the switching resolution, and the hybrid bicubic magnification is determined in step ST714. After having been obtained and set as the near-list magnification in step ST716, the respective interpolation magnifications are used to calculate step ST718.
And an interpolation process is executed in step ST720. The two-stage interpolation processing is based on different methods. The former is an interpolation processing using a so-called high-precision calculation method, and the latter is an interpolation processing using a so-called low-precision calculation method.

The reason why the two arithmetic techniques having different personalities are executed in an overlapping manner is as follows. Since the hybrid bicubic method requires a large amount of calculation processing for one interpolation pixel, it becomes impossible to employ such interpolation processing substantially when the interpolation magnification is increased. On the other hand, interpolation processing for printing is often used to eliminate differences in resolution, and the resolution of the printing device is increased in order to further improve the image quality while printing at low gradation. There are many. Then, if the dot diameter becomes smaller to some extent, there is also a reality that a highly accurate calculation processing result does not always provide good image quality. That is, when the amount exceeds a certain level, a phenomenon occurs that the image quality cannot be improved much compared to the degree of increase in the amount of arithmetic processing. For this reason, although the interpolation processing is performed up to a certain extent by the hybrid bicubic method, the image quality is not significantly changed even if the interpolation processing is performed by the near-list method, and the processing amount is relatively drastically reduced. There is.

Accordingly, after obtaining the interpolation magnification in step ST712, the hybrid bicubic cubic magnification is set in step ST714 so as to achieve this interpolation magnification in two steps.
You have to set the nearlist magnification at 16,
What is needed to make this allocation is the switching resolution. That is, in order to maintain the balance between the amount of arithmetic processing and the magnification of the image quality as described above, the switching resolution is not determined by the hybrid bicubic method but by the hybrid bicubic method. The interpolation processing is performed as described above, and the remaining interpolation magnification is subjected to the interpolation processing by the nearest method.

Also, such a switching resolution is not converted to the near-list method after the resolution is converted by the interpolation processing of the hybrid bicubic method so as to match the switching resolution. Is set as the hybrid bicubic magnification. This means that if an attempt is made to perform interpolation processing at an arbitrary magnification, all the pixels of the interpolated image data must be calculated by calculation, which requires a long calculation time. This is because it is possible to reduce the substantial amount of calculation processing by matching the grid points of the existing pixels.

Although the interpolation resolution of the hybrid bicubic method and the interpolation magnification of the near-list method are adjusted using the switching resolution, the switching resolution itself is changed in steps ST708 and ST710 according to the output resolution. The reason is as follows. As a specific example, it is assumed that the input image data is 170 dpi and 185 dpi, and the switching resolution is 180 dpi.
pi, and the output resolution is 36
A comparison will be made between a case where 0 dpi is set and a case where the output resolution is set to 720 dpi. In this case, in any case, the former image data is doubled by the hybrid bicubic method and interpolated to 340 dpi, and the latter image data is not interpolated by the hybrid bicubic method. However, when the output resolution is 360 dpi, it cannot be said that the print definition is very high. Therefore, the former image data that has passed through the hybrid bicubic method and the latter image data that has not passed through the hybrid bicubic method eventually have 360 dpi. There is no reversal of image quality when it becomes. However, the output resolution is 720 dpi
In the case of, the improvement in image quality of the former can be visually recognized as much as the resolution becomes higher, and the reverse phenomenon occurs.

Since the difference is based on such a delicate sensation, it cannot be said that it is optimal to increase the switching resolution in proportion to the output resolution. As a result, there is no other way but to decide by experiment. In the case of this embodiment,
In consideration of such balance, when the output resolution is 360 dpi, the switching resolution is set to 180 dpi, and when the output resolution is 720 dpi, the switching resolution is set to 240 dpi. That is, while the output resolution is doubled, the switching resolution is 1.33.

In this case, applying the previous example, the hybrid bicubic magnification when the output resolution is set to 720 dpi is 170 dpi.
i and 185 dpi are both switched resolution 24
Because it is smaller than 0 dpi, each is an integer multiple of 240d
Set twice to exceed pi. Then, 340 dpi by the hybrid bicubic method
And 370 dpi are interpolated, and the remaining 720/34
The 0x and 720 / 370x are interpolated by the nearest method. 340 dpi by hybrid bicubic method
And 370 dpi, the image quality does not reverse. Although the near-list magnification is not an integral multiple, it does not pose a significant problem because the original amount of calculation is small.

Step ST718 and step ST720
When the interpolation processing is completed in step ST722, the color conversion processing is performed in the following step ST722, and in step ST724, halftone processing for two gradations according to the performance of the color printer 17b is performed. According to the halftone process, it is possible to use a large number of dots to minimize the color shift macroscopically, even though the gradation is low. Then, the finally obtained print data of CMYK two gradations is output to the color printer 17b in step ST726. Therefore, the processing of steps ST722 to ST726 is a print data output step,
Considering that the print data output unit E5 is organically integrated with hardware such as U, the print data output unit E5 is configured.
Of course, the specific form of the print data changes depending on the printing apparatus, and the print data does not necessarily need to be output directly to the printing apparatus, but may be stored in a file format. Therefore, outputting print data may mean transferring data to the next stage.

As described above, the computer system 10 having the ink jet type color printer 17b and the like can be used.
In, when the resolution of the color printer 17b and the resolution of the original image data do not match, the interpolation processing is executed. The processing resolution is made to match the final resolution, and the switching resolution is changed according to the definition at the time of printing in the color printer 17b. It is possible to make it difficult for the reversal phenomenon that the image quality deteriorates in spite of the high processing load magnification and high definition being high.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to a claim of an image data interpolation device according to an embodiment of the present invention.

FIG. 2 is a block diagram of specific hardware of the image data interpolation device.

FIG. 3 is a schematic diagram showing another application example of the image data interpolation device of the present invention.

FIG. 4 is a schematic diagram showing another application example of the image data interpolation device of the present invention.

FIG. 5 is a schematic diagram showing another application example of the image data interpolation device of the present invention.

FIG. 6 is a schematic diagram showing another application example of the image data interpolation device of the present invention.

FIG. 7 is a general-purpose flowchart in the image data interpolation device of the present invention.

FIG. 8 is a more specific flowchart in the image data interpolation device of the present invention.

FIG. 9 is a diagram showing a situation where an interpolation magnification is designated from an operating system to a printer driver.

FIG. 10 is a conceptual diagram of a near-list method.

FIG. 11 is a diagram showing a situation in which data of each grid point is transferred by the near list method.

FIG. 12 is a schematic diagram showing a situation before interpolation in a near-list method.

FIG. 13 is a schematic diagram showing a situation after interpolation in the near-list method.

FIG. 14 is a conceptual diagram of the cubic method.

FIG. 15 is a diagram showing a change state of data when the cubic method is specifically applied.

FIG. 16 is a diagram showing a specific application example of the cubic method.

FIG. 17 is a diagram showing a specific application example of the hybrid bicubic method.

FIG. 18 is a conceptual diagram of a bilinear method.

FIG. 19 is a diagram showing a change state of an interpolation function.

FIG. 20 is a schematic diagram showing an integer multiple interpolation process.

FIG. 21 is a flowchart of another interpolation process.

FIG. 22 is a diagram corresponding to a claim of the image data interpolation apparatus according to one embodiment of the present invention.

FIG. 23 is a schematic block diagram of an ink jet type color printer.

FIG. 24 is a schematic explanatory view of a print head unit in the color printer.

FIG. 25 is a schematic explanatory view showing a situation in which color ink is ejected by the print head unit.

FIG. 26 is a schematic explanatory view showing a state in which a color ink is ejected by a print head of a bubble jet system.

FIG. 27 is a schematic explanatory view of an electrophotographic printer.

FIG. 28 is a flowchart showing a flow of image data in the image data interpolation apparatus.

FIG. 29 is a more specific flowchart in the image data interpolation device of the present invention.

FIG. 30 is a specific flowchart when the resolution of the printing apparatus changes.

FIG. 31 is a diagram corresponding to a claim of the image data interpolation apparatus according to one embodiment of the present invention.

FIG. 32 is a flowchart showing the flow of image data in the image data interpolation device.

FIG. 33 is a flowchart of a printing process in the image data interpolation device of the present invention.

FIG. 34 is a diagram illustrating an operation window of the printing process.

FIG. 35 illustrates an operation window for setting a printer.

[Explanation of symbols]

 10 Computer system 11a Scanner 11a2 Scanner 11b Digital still camera 11b1 Digital still camera 11b2 Digital still camera 11c Video camera 12 Computer body 12a Operating system 12b Display driver 12b Driver 12c Printer driver 12d Application 13a Floppy disk drive 13b Hard disk 13c CD-ROM drive 14a Modem 14a2 Modem 15a Keyboard 15b Mouse 17a Display 17a1 Display 17b Color printer 17b1 Color printer 17b2 Color printer 18a Color facsimile machine 18b: color copy machine

Continuation of the front page (56) References JP-A-2-27486 (JP, A) JP-A-6-89336 (JP, A) JP-A-11-96348 (JP, A) JP-A-4-8087 (JP) , A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/387-1/393 G06T 3/40

Claims (24)

(57) [Claims] 1. An image data interpolating apparatus for increasing the number of constituent pixels at a predetermined interpolation magnification for image data in which an image is represented by pixels in a dot matrix, comprising: image data acquiring means for acquiring the image data; Interpolation magnification obtaining means for obtaining an interpolation magnification of an interpolation processing to be performed on the obtained image data; and performing a plurality of interpolation processes so as to be the obtained interpolation magnification when increasing the number of constituent pixels of the image data by a predetermined interpolation processing. An image data interpolating apparatus comprising: a pixel interpolating unit that can be executed in an overlapping manner. 2. The image data interpolating apparatus according to claim 1, wherein the pixel interpolating means performs only one of the plurality of interpolation processes together with the interpolation process in which the plurality of interpolation processes are performed in an overlapping manner. An image data interpolation apparatus which is executable and has an interpolation processing selecting means for selecting an interpolation processing to be executed according to the obtained interpolation magnification. 3. The image data interpolating apparatus according to claim 1, wherein said pixel interpolating means includes an interpolation magnification of each of said superimposed interpolation processes so that said acquired interpolation magnification is obtained. An image data interpolation device characterized by determining 4. The image data interpolating apparatus according to claim 3, wherein the pixel interpolating means executes the first interpolation processing up to a certain magnification when the interpolation magnification exceeds a predetermined magnification, and performs the insufficient magnification. In a second interpolation process. 5. The image data interpolation device according to claim 3, wherein said pixel interpolation means separates the interpolation magnification into a first magnification of an integral magnification and a second magnification of a shortage, and An image data interpolation apparatus, wherein the interpolation processing is performed at a first magnification in the interpolation processing, and the interpolation processing is performed at a second magnification in the second interpolation processing. 6. The image data interpolating apparatus according to claim 3, wherein the interpolation magnification obtaining means detects a resolution at the time of printing, and the pixel interpolation means determines a resolution based on the interpolation magnification based on the resolution. An image data interpolation device, wherein an interpolation magnification of one interpolation processing and an interpolation magnification of a second interpolation processing are determined. 7. The image data interpolating device according to claim 6, wherein the pixel interpolation means sets the first interpolation magnification to be lower than a resolution of a predetermined integral number based on the detected resolution. An image data interpolating apparatus, wherein an integer multiple is set, and subsequently, a shortage is set as the second interpolation magnification. 8. The image data interpolating apparatus according to claim 1, wherein said pixel interpolating means performs an advanced operation relative to image data of existing constituent pixels in said interpolation processing. The method is characterized in that the image data of the interpolated pixel is generated by performing the processing, and in the subsequent interpolation processing, the image data of the interpolated pixel is generated by performing relatively simple arithmetic processing on the image data of the existing constituent pixels. Image data interpolation device. 9. A step of obtaining the image data when increasing the number of constituent pixels at a predetermined interpolation magnification with respect to image data representing an image by dot matrix pixels, and performing interpolation to be performed on the obtained image data. A step of acquiring an interpolation magnification of the processing, and a step of increasing the number of constituent pixels of the image data by executing a plurality of interpolation processings so that the plurality of interpolation processings can be executed and the acquired interpolation magnifications are obtained. An image data interpolation method, which is performed. 10. The image data interpolation method according to claim 9, wherein a plurality of interpolation processes are performed in an overlapping manner, and only one of the plurality of interpolation processes can be performed. An image data interpolation method, wherein an interpolation process to be executed is selected according to an obtained interpolation magnification. 11. The image data interpolation method according to claim 9 or 10, wherein an interpolation magnification of each of the interpolation processes executed so as to be the acquired interpolation magnification is determined. Image data interpolation method. 12. The image data interpolation method according to claim 11, wherein when the interpolation magnification exceeds a predetermined magnification, the first interpolation processing is performed up to a certain magnification, and the insufficient magnification is changed to the second interpolation processing. An image data interpolation method characterized by being executed by: 13. The image data interpolation method according to claim 11, wherein said interpolation magnification is divided into a first magnification of an integral magnification and a second magnification of a shortage. An image data interpolation method, wherein an interpolation process is executed at one magnification, and an interpolation process is executed at the second magnification in the second interpolation process. 14. The image data interpolation method according to claim 11, wherein the resolution at the time of printing is detected, and the interpolation magnification of the first interpolation processing and the second interpolation processing are determined according to the interpolation magnification based on the resolution. And determining the interpolation magnification of the image data. 15. The image data interpolation method according to claim 14, wherein the first interpolation magnification is set to an integer multiple that is lower than a resolution of a predetermined integral number based on the detected resolution. And an image data interpolation method, wherein a shortage is set as the second interpolation magnification. 16. The image data interpolation method according to any one of claims 9 to 15, wherein in said interpolation processing, image data of existing constituent pixels is subjected to relatively advanced arithmetic processing to perform interpolation pixel interpolation. Generate image data for
An image data interpolation method characterized in that in subsequent interpolation processing, image data of interpolated pixels is generated by performing relatively simple arithmetic processing on image data of existing constituent pixels. 17. A medium storing an image data interpolation program for causing a computer to execute a plurality of interpolation processes in a superimposed manner so as to increase the number of constituent pixels at a predetermined interpolation magnification for image data in which an image is represented by pixels in a dot matrix. Obtaining the image data; obtaining an interpolation magnification of an interpolation process to be performed on the obtained image data; and performing the plurality of interpolation processes to obtain the obtained interpolation magnification. And causing the computer to execute a plurality of interpolation processes in an overlapping manner to increase the number of constituent pixels of the image data. 18. A medium on which the image data interpolation program according to claim 17 is recorded, wherein only one of a plurality of interpolation processes can be executed together with an interpolation process in which a plurality of interpolation processes are executed. A medium for recording an image data interpolation program, wherein an interpolation process to be executed is selected according to the obtained interpolation magnification. 19. A medium in which the image data interpolation program according to claim 17 or 18 is recorded, wherein an interpolation magnification of each of the superimposed interpolation processes is determined so as to be the acquired interpolation magnification. A medium on which an image data interpolation program is recorded. 20. A medium in which the image data interpolation program according to claim 19 is recorded, when the interpolation magnification exceeds a predetermined magnification, the first interpolation processing is executed until a certain magnification is set, and the insufficient magnification is set to the second magnification. A medium in which an image data interpolation program recorded in a second interpolation process is recorded. 21. A medium in which the image data interpolation program according to claim 19 is recorded, wherein said interpolation magnification is divided into a first magnification of an integral magnification and a second magnification of a shortage. A medium in which an image data interpolation program is recorded, wherein in the processing, the interpolation processing is executed at the first magnification, and in the second interpolation processing, the interpolation processing is executed at the second magnification. 22. A medium on which the image data interpolation program according to claim 19 is recorded, wherein a resolution at the time of printing is detected, and the interpolation magnification of the first interpolation processing is determined based on the interpolation magnification based on the resolution. A medium on which an image data interpolation program is recorded, wherein an interpolation magnification of the second interpolation processing is determined. 23. A medium on which the image data interpolation program according to claim 22 is recorded, wherein the first interpolation magnification is an integer lower than a resolution of a predetermined integer based on the detected resolution. A medium on which an image data interpolation program is recorded, wherein the image data interpolation program is set to a magnification of 2, and subsequently, a shortage is set as the second interpolation magnification. 24. A medium in which an image data interpolation program according to any one of claims 17 to 23 is recorded, wherein in the interpolation processing, advanced arithmetic processing is performed relatively to image data of existing constituent pixels. Image data of the interpolated pixel in the subsequent interpolation process by applying a relatively simple operation to the image data of the existing constituent pixels in the subsequent interpolation process. Medium on which interpolation program is recorded.