JP3266576B2 - Image processing apparatus, image output apparatus, image processing method, and recording medium storing image processing 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 processing device, an image output device, and an image processing device for visually smoothing jaggies (jaggies) at an edge portion as necessary when outputting characters, line drawings, and the like. The present invention relates to a method and a recording medium that records an image processing program for causing a computer to execute the image processing.

[0002]

2. Description of the Related Art Generally, when code image data such as PDL (Page Description Language) is used, image data such as a photograph, an image in which line drawings, characters, and the like are mixed are output by a common output device in terminals of different models. Or output in common in different output devices. For this reason, the code image data is widely used when performing image output. As is well known, such code image data defines the drawing area with vector data and outline data according to various drawing commands, and therefore, when outputting to a printer or display, interprets the contents of the code image data. Must be developed (converted) into drawing pattern data as image data.

[0003] Here, FIG.
Consider the case where a straight line is drawn as shown in FIG. In this case, if the area to be drawn covers a pixel at all, a binarization process using the pixel as a drawing area is executed and developed, and as shown in FIG. The border (edge) of the line to be drawn
In some parts, jaggies are noticeable.

Therefore, when outputting a character or a line drawing, an anti-aliasing (smoothing) process for visually smoothing jaggies is applied. An example of this processing will be described with respect to a case where the pixel at the edge portion circled in FIG. 1A is in the state shown in FIG. 1C. First, FIG. Thus, this pixel is divided into a plurality of (for example, 16) sub-pixels.
Second, for example, if the area to be drawn is half or more of the area of the sub-pixel, as shown in FIG.
While giving the sub-pixel a pixel value of “1”,
Otherwise, a pixel value of “0” is given to the sub-pixel. There are various methods for determining the pixel value. Third, the sum of the pixel values of the divided sub-pixels is set as a multi-valued pixel value for the pixel. In the example shown in this figure, the pixel value of the pixel is multi-valued as “10”. When pixels of a character, a line drawing, or the like are subjected to multi-value processing in this manner, the pixels in the edge portion have intermediate gradations between an area to be drawn and an area not to be drawn, so that jaggy is visually suppressed. In the examples shown in FIGS. 16D and 16E, since one pixel is divided into 16 sub-pixels, the gradation by multi-valued conversion is from “0” to “0”.
Although there are 17 tones of "16", the number of tones can be further increased by dividing into a large number of sub-pixels.

Japanese Patent Application Laid-Open No. 4-195268 describes a technique for optimizing the shape of sub-pixels and the number of divisions according to the inclination of vector data at the time of multi-value processing. Even with this technique, it is possible to make the jaggy inconspicuous. As described above, by arranging multivalued pixels at the edge portion of the vector data in the code image data, it is possible to improve the output quality.

[0006]

However, in order to develop the vector data into multi-valued drawing pattern data, it is necessary to develop the vector data at a resolution higher than the resolution of the output device due to the division into sub-pixels. , Even temporarily,
It needs to be kept. For this reason, there is a problem that a larger memory capacity is required and the processing time is longer than when no anti-aliasing processing is performed.

[0007] As shown in FIG. 17A, consider the case of drawing a line having a width smaller than the size of one pixel. In this case, if the area to be drawn covers any pixel, the pixel is set to “1”, or
If the area to be drawn is located at the center of the pixel, the binarization process for setting the pixel to “1” will result in the result shown in FIG. On the other hand, when the above-described multi-value processing is performed on the line shown in FIG. 3A, the pixel value becomes a very small value, and the density of the output line is reduced as a result. . Therefore, in some cases, the binarization processing may be more excellent than the multi-level processing in terms of output quality, recognizability in optical reading, and the like. Note that in the example shown in the figure, the pixel value “1” in the case of performing the binarization processing corresponds to the pixel value “16” in the case of performing the multi-level processing, and in each case, the density of the pixel is “100”. % ".

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to execute anti-aliasing processing as required when developing code image data into drawing pattern data. By doing
An image processing apparatus capable of generating high-quality drawing pattern data without requiring a large-capacity memory, shortening the processing time, and making the jaggies inconspicuous, and an image capable of outputting the image. An object of the present invention is to provide an output device, an image processing method, and a recording medium that stores an image processing program for causing a computer to execute the image processing.

[0009]

According to the present invention, there is provided an image processing apparatus for developing code image data into drawing pattern data, wherein the code image data is converted into binarized drawing pattern data. First expanding means for expanding, second developing means for expanding the code image data into multi-valued drawing pattern data, and determining whether or not the code image data is data satisfying a predetermined condition. And a selection unit that selects and applies one of the first and second expansion units as expansion unit that expands the code image data based on the determination by the condition determination unit. It is characterized by:

(Operation) According to the present invention, when interpreting code image data describing a drawing command such as a character or a line drawing and developing the same into drawing pattern data as a bit image, an edge portion such as a character or a line drawing is used. May be conspicuous, but the processing speed is high for the first developing means or the second developing means for multi-valued and visually smoothing the edges of characters and line drawings. Is appropriately selected and applied depending on the scene or situation, that is, whether or not the code image data is data that meets a predetermined condition. Here, the predetermined condition as a criterion for selection may be, for example, the length, width, angle, etc., when a line image is output. The reason is that the jaggies at the edges become more noticeable as either the length or width of the line is smaller than the pixel, or the angle of the line is closer to the horizontal or vertical, so it depends on the line width or angle. This is because it is necessary to appropriately select a developing means used for the developing process. Further, when outputting a character, the predetermined condition as a criterion for selection is appropriate in its font, size, character code, and the like. This is because these individual conditions determine whether or not jaggies are noticeable in the edge portion of the character. On the other hand, it is necessary to consider that the processing speed may be prioritized over the output quality. In this case, since the time required for the processing of the second expanding means is longer than that of the first expanding means, the time required for the former processing is estimated, and the expanding means used for the expanding processing is determined based on the prediction result. If you make a choice, you get the desired result. Further, as a criterion for selection, judgment by the user is also important. For this reason, it is desirable that the user himself / herself be able to select the developing means used for the developing process.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

<1: First Embodiment><1-1: Overall Configuration> FIG. 1 is a block diagram showing the overall configuration of a system including an image processing unit according to a first embodiment of the present invention. In this figure, a host computer 10
0 outputs image data to be output as code image data such as PDL. Image processing unit 200
Is to interpret the code image data and develop it into raster data (rendering pattern data) indicating a raster image by using character outline data and line drawing vector data. Also, the image output unit 300
Is for outputting an image in accordance with raster data, and corresponds to a printer, a display, or the like.

Here, although there is no significance in strictly distinguishing the outline data and the vector data, for convenience of explanation, information defining the outline of a character is called outline data.
Information that defines the outline or end point of a line drawing is called vector data. When outputting characters,
Data such as character codes that specify the characters to be output, typeface, size, style (such as italic), stroke weight (such as bold), outline data that defines the outline of the characters, and coordinate data to be drawn on the page are required. These are collectively called font data.

FIG. 1 merely shows each block of the system separately for convenience of explanation. That is, the image processing unit 200 may actually expand the code image data into raster data as one function of the host computer 100, or
0 may be developed as one function. Further, there is a case of a stand-alone type as shown in the figure. Here, when the image processing unit 200 is a function of the host computer 100, the host computer 100 executes the same operation as an image processing unit described later with a predetermined program to expand the code image data into raster data. And output. On the other hand, when the function is one of the functions of the image output unit 300 as in the latter case, the image output unit 300
Similarly, by performing the same operation as that of the image processing unit, the code image data is developed into raster data, and an image is output based on this data. Also,
In any case, the connection form between the blocks does not matter. That is, it may be via a network or directly connected by a cable.

<1-1-1: Image Processing Unit> Next, the detailed configuration of the image processing unit 200 will be described. Here, in principle, as shown in FIG. 1, the image processing unit 200 is of a stand-alone type or the image output unit 3
A case where the function is 00 will be described.

<1-1-1-1: Hardware Configuration><1-1-1-2: First, the hardware configuration of the image processing unit will be described with reference to FIG. In this figure, a CPU 201 constructs a function block, which will be described later, by a program stored in a ROM 202 and executes a development process. At this time, a RAM 203 is temporarily used as a work area. Also, the RAM 203
In addition, there may be a case where a font table that specifies a development method of a character to be output, a character code table that specifies a development method for each character code, and the like are stored. The contents of these tables will be described later. On the other hand, a data input I / F (interface) 204 is for inputting code image data to be expanded.

Next, the operation panel 205 is for inputting user's operations and instructions. In this embodiment, in particular,
It is used to set the contents of a font table and a character code table, which will be described later, and to specify multi-value expansion. Here, the designation of the multi-value expansion is a state in which the user has specified the permission of the anti-aliasing process, and is synonymous with “multi-value expansion is possible” described later. This is performed by the user responding to the screen as shown in FIG. In this setting, when an instruction to disallow anti-aliasing processing by multi-valued expansion such as “high speed” or “binary expansion” is given, only binary expansion is designated, while When priority is given to image quality, such as "image quality" or "multi-value expansion", multi-value expansion is specified, and binary expansion or multi-value expansion is selected and expanded according to the procedure described later. Will be executed. The setting items on the operation panel 205, including the contents of the font table and the character code table, can be set remotely from the host computer 100.

The image storage unit 206 is a so-called page memory, and temporarily stores raster data for each page. That is, the image storage unit 206 corresponds to the resolution of the image output unit 300, and its pixels and storage areas correspond one-to-one. The image output I / F 207 is for outputting the raster data stored in the image storage unit 206 to the image output unit 300. Note that it is not necessary to strictly distinguish the RAM 203 and the image storage unit 206, and an area allocated as a part of the RAM 203 is actually used as the image storage unit 206.

Here, when the image processing unit 200 is a function of the host computer 100, the CPU 201
A function block to be described later is constructed by the OS, the application program, and the like, and the expansion processing is executed. In this case, if there is a portion for receiving the code image data from the OS or the application program, it is not necessary to separately provide the data input I / F 204.

<1-1-1-3: Functional Configuration> Next, the functional configuration of the image processing unit 200 constructed by the hardware configuration shown in FIG. 2 will be described with reference to FIG. . In this figure, a code image data storage unit 25
1 stores code image data received from the host computer 100. Such a code image data storage unit 251 is equivalent to temporarily storing code image data input by the CPU 201 in FIG. 2 via the data input I / F 204 in the RAM 203.

The expansion method determination unit 252 determines whether to apply binary expansion or multi-value expansion in expansion of characters and line drawings in accordance with a procedure described later. The expansion method selection unit 253 expands the code image data stored in the code image data storage unit 251 by either the binary expansion unit 254 or the multi-value expansion unit 255 according to the result determined by the expansion method determination unit 252. To be supplied to the department.

The binarizing section 254 simply binarizes the code image data into raster data. On the other hand, the multi-value developing unit 255 performs multi-value expansion of the code image data into raster data and performs an anti-aliasing process. The expansion method determination unit 252, the expansion method selection unit 253, the binary expansion unit 254, and the multi-value expansion unit 255 include the CPU 201 in FIG.
The font data and vector data included in the code image data stored in M203 are interpreted to determine which expansion method is to be used. Second, the outline data and vector data are determined according to the determination result. It is equivalent to expanding with the expanded method.

The image storage unit 206 combines raster data developed by the binary development unit 254 or the multi-value development unit 255 for each page and stores the combined data. That is, the CPU 201 in FIG. 2 writes the raster data developed by one of the methods at the address corresponding to the coordinates to be drawn on the page in the image storage unit 206. Then, the raster data stored in the image storage unit 206 is read out according to the scanning direction of the image output unit 300, and the image output unit 300 actually outputs the image.

The image storage unit 206 identifies whether the stored raster data is expanded by the binary expansion unit 254 or expanded by the multi-value expansion unit 255. Data is stored for each pixel. Here, the raster data and the corresponding identification data may be stored in the same area, or may be stored separately as long as the correspondence between them is ensured. And when raster data is read,
The identification data corresponding to the pixel is also read at the same time,
It is supplied to the image output unit 300. This allows the image output unit 300 to perform processing such as changing the number of screen lines when outputting multi-valued pixels.

<1-1-2: Font Table> Here, the font table used in the present embodiment will be described with reference to FIG. As shown in this figure, the font table includes Mincho, Gothic, Ti
mes, Arial, Courier, Century
The expansion method is specified for each typeface. Here, “only binary expansion” in the specification of the expansion method prohibits the expansion method selection unit 253 from selecting the multi-value expansion unit 255 when rasterizing characters into raster data. This is mainly specified when the priority is given to the expansion processing speed. On the other hand, “multi-value expansion is possible” is to permit the expansion method selection unit 253 to select the binary expansion unit 254 and the multi-value expansion unit 255 when raster data is expanded. Which one to select is left to a determination procedure described later.

Therefore, from a different point of view, in principle, by specifying “multi-value expansion”, binary or multi-value expansion is permitted, but as an exception, “binary expansion only” is specified. , Multi-value expansion is prohibited, and the relationship is the same as the above-described relationship in the user specification of multi-value expansion.

In FIG. 5, the expansion method can be specified for each typeface. Alternatively, the expansion method may be specified according to the style and the stroke weight.

<1-1-3: Character Code Table> Next, a character code table used in the present embodiment will be described with reference to FIG. As shown in this figure, the character code table specifies an expansion method for each character code that defines a character. That is, in the present embodiment, it is possible to specify the expansion method not only for each typeface but also for the characters themselves. In Japanese fonts such as Mincho and Gothic, distinctions such as alphanumeric characters, hiragana, katakana, and kanji can be classified by a code system. For this reason, in a Japanese font, it is also possible to specify an expansion method for each distinction of alphanumeric characters, hiragana, katakana, kanji, and the like. Regardless of the character code system, JI
Various types such as S, shift JIS, breakpoints, and Unicode can be used.

<1-2: Operation of Embodiment> Next, the operation of the image processing section 200 according to the above embodiment will be described. First, the overall operation of the image processing unit 200 will be described with reference to FIG. First, the host computer 10
0, the image processing unit 2
00 receives the PDL code image data in step S101 and interprets its meaning. Then, the image processing unit 200 determines in step S102
Objects whose drawing is instructed by the code image data are identified one by one.

Here, if the identified object is a character, the image processing unit 200 executes drawing of the character in step S103, and the identified object is determined to be a ruled line, a table, a straight line, a curve, a polygon, or the like. If it is a line drawing, drawing of the line drawing is executed in step S104. In addition,
Here, the term “rendering” refers to processing for expanding outline data of a character or vector data of a line drawing into raster data and storing the raster data in the image storage unit 206, and details thereof will be described later. On the other hand, if the identified object is raster (image) data such as a photograph or a picture, the image processing unit 200 executes appropriate processing such as filter processing, gradation adjustment processing, and rotation / enlargement / reduction processing in step S105. The raster data after the processing is stored in the image storage unit 20.
6 is stored.

Next, the image processing section 200 determines whether or not the object to be drawn has been processed for all pages to be output. If the determination result is negative, the process returns to step S101. On the other hand, if the object to be drawn is processed for all pages, the result of this determination is affirmative.
At 07, the stored raster data is read out and supplied according to the scanning direction of the image output unit 300.
As described above, upon receiving the code image data, the image processing unit 200 interprets the meaning of the code image data and executes a process according to the object to be drawn.

<1-2-1: In case of character output>
If the identified object is a character, step S
The character drawing processing executed in step 103 will be described in detail.

<1-2-1-1: Determination of Expansion Method> First, the expansion method determination unit 252 of the image processing unit 200 determines whether to apply multi-value expansion to an object identified as a character. Determine if value expansion should be applied.
FIG. 8 is a flowchart showing the determination procedure.

As shown in this figure, when outputting an object identified as a character, the expansion method determination unit 252
First, in step S201, it is determined whether or not multi-value expansion has been designated by the user. Here, the designation of the multi-value expansion means that the user operates the operation panel 2 as described above.
05 or a state in which the permission of the anti-aliasing process is designated by the operation of the host computer 100.
The expansion method determination unit 252 determines the application of binary expansion to the character if multi-level expansion has not been specified, and if multi-level expansion has been specified, further proceeds to step S2
In 02, the time required for multi-value expansion of the character is predicted, and it is determined whether or not the predicted time is shorter than a time Tmax which is a threshold value.

In the present embodiment, both the time required for binary expansion and the time required for multi-level expansion are estimated. Here, when the time for calculating the sum of the pixel values of the sub-pixels for each pixel in the multi-valued development can be ignored, the time required for the multi-valued development is determined by dividing the pixel into a plurality of sub-pixels. In relation to this, it can be considered that the time required for the binary expansion is times the number of subpixels obtained by dividing one pixel. In addition, if the number of outline control points of a character increases, the character becomes complicated, so that it takes time to develop the character. The outline control point (also referred to as a segment) of a character is, for example, as shown in FIG.
2 (a), as indicated by a circle, a coordinate point defining an outline of a character, which is included in font data of the character.

Accordingly, the time required for the binary expansion of a character is determined by interpreting the font data of the character and obtaining elements such as the total number of outline control points, and by adding a coefficient corresponding to the processing speed to each of these elements. By multiplying and obtaining the sum, it is possible to calculate easily, and the time required for multi-value expansion of characters is
The time required for the binary expansion can be calculated as the time obtained by multiplying the number of subpixels of one pixel. If the sum calculation time for the pixel value of the sub-pixel cannot be ignored in the multi-value expansion, the time required for the multi-value expansion includes:
Further, the total sum calculation time is added.

If it is determined that the time required for the multi-value expansion predicted in this way is equal to or longer than the time Tmax, the expansion method determination unit 252 determines the application of the binary expansion to the character, while Is shorter than the time Tmax, the determination in step S203 is further performed. In step S202, the expansion method determination unit 252 does not determine whether the time required for multi-value expansion of the character is shorter than the time Tmax. The time required for the value development may be compared, and the determination may be made based on the comparison result. For example, it may be determined whether or not the difference between them is within a threshold value, or may be determined by combining the difference between the two and the time required for multi-value expansion of a character.

The step S202 of estimating the time required for character expansion is not a processing directly contributing to speeding up of the expansion processing, but rather a processing having a dead time meaning from the viewpoint of the entire expansion processing. Therefore, spending more time than necessary on this prediction does not meet the purpose of the present invention of shortening the processing time. Therefore,
The expansion method determination unit 252 determines in step S202
If the time required for multi-value expansion of a character cannot be obtained even after a certain time has elapsed, the subsequent determination procedure (selection condition) is changed. For example, in this case, the expansion method determination unit 252 forcibly skips the procedure to step S203 or determines the application of binary expansion to the character.

In step S203, the expansion method determination unit 252 interprets the font data of the character to be output, and determines whether or not the expansion method is designated as "multi-value expansion possible" for the typeface. The determination is made with reference to the font table shown in FIG. If the expansion method determination unit 252 determines that the specification of the expansion method in the typeface of the character is “only binary expansion”, the expansion method determination unit 252 determines the application of the binary expansion to the character, If it is determined that “deployment is possible”, further in step S204,
It is determined whether or not the size of the character is equal to or smaller than a threshold value Smax.

Here, as the size of the character increases, the number of pixels constituting the character increases accordingly, so that it takes time to develop the character, and the pixels become relatively small with respect to the character. The jaggies are not noticeable by the binarization. Conversely, the smaller the character size, the smaller the number of pixels that make up the character,
Since it does not take much time to develop a character and the pixels are relatively large with respect to the character, jaggies are noticeable according to the binarization.

Therefore, the expansion method determination unit 252 interprets the font data of the character and, when determining that the character size is equal to or larger than the threshold value Smax, determines the application of the binary expansion to the character. On the other hand, if it is determined that the character size is smaller than the threshold value Smax, it is further determined in step S203 whether or not the character code of the character is a multivalued expanded character code. Here, the multi-value expansion character code is a character code in which “multi-value expansion is possible” is specified in the character code table shown in FIG.
The expansion method determination unit 252 interprets the font data of the character and, when determining that the character code is not a multi-value expansion character code, determines application of binary expansion to the character, If it is determined that the character code is an expanded character code, the application of multi-value expansion to the character is determined. Therefore, when the character is a Japanese font, the expansion method determining unit 252 determines the expansion method according to whether the character is an alphanumeric character, a hiragana, a katakana, or a kanji.

<1-2-1-2: Drawing of Character> As described above, when the identified object is a character, the expansion method determination unit 252 performs multi-level expansion on the character to be output. Determine whether to apply or binary expansion. According to the determination, the expansion method selection unit 253 supplies the font data for the character to either the binary expansion unit 254 or the multi-value expansion unit 255 according to the determination. Binary expansion section 254 or multi-level expansion section 255
Expands into raster data by using each font system using font data of the character. next,
This expansion processing will be described in detail. FIG. 10 is a flowchart showing a processing procedure of the development. In this figure, steps S401 to S403 are performed by a binary developing unit 254.
Step S404 is executed only by the binary expansion section 255, while steps S405 to S406 are executed only by the multilevel expansion section 255. .

First, the processing of binary expansion will be described. First, in step S401, the binary developing unit 254 interprets font data of a character to be output and decodes outline data, hint information, and the like. Among them, the hint information is information for forcibly specifying a character expansion method for a part of the character. For example, the outline of the numeral “4” in the typeface “Century” is as shown in FIG. 11, but depending on the development method and size, the lines L11 and L1
2 is too thin or disappears and is confused with the number "1". Therefore, the hint information is such that the pixels on such lines L11 and L12 are developed so as not to be intentionally fattened or lost. Note that the hint information in this case is information that specifies that pixels on the lines L11 and L12 are forcibly set as a drawing area.

Next, the binary expansion unit 254 determines in step S4
In 02, the outline control point of the outline data is positioned at the size specified by the size data and the coordinates specified by the coordinate data in the pixel array corresponding to the resolution of the image output unit 300. For example, the outline control point of the number “4” in the typeface “Century” is a point indicated by a circle in FIG. 12A, and the binary expansion unit 254 determines this as shown in FIG. Next, positioning is performed with respect to the pixel array corresponding to the resolution of the image output unit 300 at the size specified by the size data and the coordinates specified by the coordinate data. Here, when it is specified that some control points positioned in the pixel array are connected by a curve, the binary developing unit 254 approximates the curve with a plurality of straight lines as necessary in step S403. Note that the processing in step S403 is optional.

Further, in step S404, the binary developing unit 254 gives a pixel value to each pixel in the closed region surrounded by the positioned control point by using a predetermined algorithm. For example, if the closed area covers any pixel, a pixel value of “1” is given (filled) to the pixel, whereas a pixel value of “0” is given to the pixel (not filled) otherwise. . Then, the binary developing unit 254 writes this processing result in an area of the image storage unit 206 corresponding to the pixels of the image output unit 300 on a one-to-one basis. As a result, in the image storage unit 206, raster data indicating whether or not the pixel should be painted is binarized and stored in an area corresponding to each pixel of the image output unit 300. Here, when such a binarization process is executed in a closed region where the outline control point is positioned as shown in FIG. 12B, for example, as shown in FIG. The pixels in the region are filled together with the edge portions.

Further, at the time of the binary development, the binary developing unit 254 also writes identification data indicating that the raster data has been binary-developed in an area associated with the pixel in the image storage unit 206. The binary developing unit 254 performs the rasterization using the font data on all the characters for which the binary development is determined to be applied.

Next, the multi-value expansion processing will be described.
In this case, the multi-level developing unit 255 performs the same operation as the binary developing unit 254 from step S401 to S403. That is, the multi-value expansion unit 255 determines in step S40
In step S1, the font data is interpreted and necessary information is decoded. In step S402, the outline control points of the outline data are positioned in a pixel array corresponding to the resolution of the image output unit 300. In, a curve connecting several positioned control points is approximated by a plurality of straight lines.

Here, the multi-value developing unit 255 converts each pixel in the closed region surrounded by the positioned control point into a pixel in step S40.
In step 5, each pixel is divided into sub-pixels, and a pixel value is given to each sub-pixel by a predetermined algorithm. For example, if the area of the closed region is equal to or more than half of the area of the sub-pixel, the pixel value of “1” is given to the sub-pixel. Otherwise, the pixel value of “0” is given to the sub-pixel. Further, step S40
In 6, the sum of the pixel values given to the sub-pixels is calculated for each pixel, and the multi-valued pixel value is calculated for the pixel in the area corresponding to the pixel of the image output unit 300 on a one-to-one basis in the image storage unit 206. Write. As a result, in the image storage unit 206, raster data indicating the area gradient of the pixel is multi-valued and stored in a region corresponding to each pixel of the image output unit 300. Therefore, when such a multi-value processing is executed in a closed area where the outline control point is positioned as shown in FIG. 11B, for example, as shown in FIG. The edge portion has a pixel value corresponding to the area ratio of the closed region, while the portion other than the edge portion has the lowest or highest gradation number according to the number of sub-pixel divisions according to the presence or absence of drawing. Value.

Further, at the time of multi-value development, the multi-value development unit 255 also writes identification data indicating that the raster data has been multi-value developed into an area associated with the pixel in the image storage unit 206. Thus, the multi-value expansion unit 2
Reference numeral 55 executes development to raster data using font data for all characters for which application of multi-value development has been determined.

<1-2-2: Case of Line Drawing Output> Next, the line drawing processing executed in step S104 of FIG. 7 when the identified object is a line drawing will be described.

<1-2-2-1: Determination of Expansion Method> The expansion method determination unit 252 performs multi-level expansion on an object identified as a line drawing in the same manner as a character, according to the flowchart shown in FIG. It is determined whether the processing should be applied or the binary expansion processing should be applied.

First, when outputting an object identified as a line drawing, the expansion method determination unit 252 determines in step S30
In step 1, it is determined whether or not the user has designated the multi-value expansion. If the multi-level expansion is not specified, the expansion method determination unit 252 determines the application of the binary expansion to the line drawing. On the other hand, if the multi-level expansion is specified, the expansion method determination unit 252 further proceeds to step S302. The time T required for predicting the time required for multi-value expansion and the predicted time being a threshold
It is determined whether or not it is shorter than max.

Here, as the length of the line drawing to be output becomes longer, the number of pixels constituting the line drawing increases, so that it takes time to develop. Therefore, the time required for the development of the line drawing is determined by interpreting vector data of the line drawing, obtaining elements such as the length of the line drawing by a method described later, and multiplying each of these elements by a coefficient corresponding to the processing speed. By calculating the sum, it is possible to easily calculate the sum. In addition, the time required for multi-value development of a line drawing is the same as the time required for binary development for one character.
This can be calculated as the time multiplied by the number of sub-pixels of the pixel. If the sum calculation time for the pixel value of the sub-pixel cannot be ignored in the multi-value expansion,
The time required for multi-value expansion of a line drawing is added to the sum calculation time, similarly to the case of characters.

If it is determined that the time required for the multi-value expansion predicted in this way is equal to or longer than the time Tmax, the expansion method determination unit 252 determines the application of the binary expansion to the line image, Is shorter than the time Tmax, the determination in step S303 is further performed. In step S302, the development method determination unit 252 does not determine whether the time required for the multi-value development of the line drawing is shorter than the time Tmax. It is the same as in the case of a character that both the time required for value development and the determination may be compared based on the comparison result. Also, the deployment method determination unit 252
However, in the case where it is not possible to obtain the time required for multi-value expansion of the line drawing even after a certain time has elapsed in step S302, the subsequent determination procedure may be changed, similarly to the case of the character.

In step S303, the expansion method determination unit 252 interprets the vector data of the line drawing to be output, and determines whether or not the angle of the line drawing is nearly horizontal or vertical by a method described later. here,
It is well known that jaggies become more noticeable as the angle of the line drawing approaches horizontal or vertical. Therefore, if the angle of the line image is not close to horizontal or vertical, the expansion method determination unit 252 determines the application of the binary expansion to the line image. Is the threshold Lma
Determine whether it is shorter than x.

In general, as the length of a line drawing increases, the number of pixels constituting the line drawing increases accordingly. As described above, it takes time to develop the line drawing. For this reason, the deployment method determination unit 2
52 interprets the vector data of the line drawing, obtains the length of the line drawing by a method described later, and determines that the binary expansion is applied to the line drawing when it is determined that the length is equal to or larger than the threshold value Lmax. On the other hand, if it is determined that the line drawing is shorter than the threshold Lmax, the line width of the line image is wider than the threshold Win in step S305, and
It is determined whether or not it is smaller than the threshold value Wmax. here,
The length and line width of a line drawing are two sides of the same coin, and if one is considered as a line width, the other can be considered as a length. For this reason,
The expansion method determination unit 252 interprets the vector data of the line image to determine the line width, and if it is determined that the line width is equal to or larger than the threshold value Wmax, determines the application of the binary expansion to the line image. On the other hand, if it is determined that the line drawing is smaller than the threshold value Wmax, the application of the multi-value expansion to the line drawing is determined. However, when the line drawing is short and the line width is narrow, the line drawing is a drawing with a very small area, and it is considered that jaggies are not conspicuous. For this reason, the deployment method determination unit 252
If it is determined in step S305 that the line width is smaller than the threshold value Win, the application of binary expansion to the line drawing is determined.

Here, the calculation of the angle, length and line width of a line drawing will be described. Generally, when a line drawing is output using PDL, end points such as a start point and an end point are designated by coordinates on a page. Here, as shown in FIG. 13, a straight line to be drawn is defined by two end points A and B, and their coordinates are A (xa, ya) and B, respectively.
When represented by (xb, yb), the angle α between the straight line AB connecting the two and the X axis on the page is given by the following equation.

When xa ≠ xb α = tan ⁻¹ {(yb−ya) / (xb−xa)} When xa = xb α = π / 2

The length L of the straight line AB is given by the following equation. L = {(xb−xa) ² + (yb−ya) ² }

On the other hand, when a line drawing having a line width is output using PDL, as shown in FIG. 14, a method of designating the line width together with its start point and end point by a scale on a page, and FIG. As described above, a method of designating the diagonal coordinates by the coordinates on the page can be considered. Here, in the method shown in FIG. 14, the line width of the straight line AB is W (in other words, (xb−xa) is considered to be the line width). Further, in the method shown in FIG. 15, the line width of the straight line AB is (yb-ya) (in other words, (xb-xa)
Is considered the line width).

As described above, the development method determination unit 252 interprets the vector data of the line drawing and obtains the angle, length, and line width of the line drawing, thereby obtaining the step S30.
1 to S305 can be determined.

<1-2-2-2: Drawing of Line Drawing> As described above, when the identified object is a line drawing, the expansion method determination unit 252 applies multi-value expansion or binary expansion. To decide. According to the determination, the expansion method selection unit 253 converts the vector data of the line drawing into
According to the determination, the data is supplied to either the binary expansion unit 254 or the multi-level expansion unit 255. Binary expansion unit 25
The 4 or multi-value expansion unit 255 expands the vector data relating to the line drawing into raster data according to each expansion method. These processing procedures are basically the same as the character drawing shown in FIG. 10, except that there is no concept of size in character development. For this reason, the binary expansion unit 254 or the multi-level expansion unit 255 interprets the end point information of the vector data in step S401, and determines the end point in the pixel array corresponding to the resolution of the image output unit 300 in step S402. It will be positioned at the specified coordinates. Subsequent procedures are the same as those for characters. That is, the binary expansion unit 2
Numeral 54 binarizes the closed region surrounded by the end points, while the multi-level developing unit 255 binarizes the closed region.

The above operation is performed on all the character and line drawing objects included in the code image data, and is developed into raster data by the binary developing unit 254 or the multi-value developing unit 255, and the image is displayed together with the identification data. The data is stored in the corresponding area of the storage unit 206.
In addition, after processing the raster (image) data appropriately,
The data is stored in the corresponding area of the image storage unit 206.
Since raster (image) data is multi-valued,
This is indicated by the identification data. Then, the image storage unit 2
The raster data and identification data stored in 06 are
It is read out according to the scanning direction of the image output unit 300. Here, the image output unit 300 performs the image formation based on the raster data at the highest screen ruling, for example, if it indicates that the identification data has been binarized.
If it is indicated that the identification data has been converted into multi-valued data, the image formation based on the raster data is executed with a reduced screen ruling. Thereby, the binarized raster data is
While the raster data is output at the highest resolution, the multi-valued raster data is output as an image at an intermediate gradation.

<2: Second Embodiment><2-1: Assumption of Embodiment> Next, a second embodiment of the present invention will be described. The problems that occur will be described.

<2-1-1: Output of Sub-Pixel> When a laser system is adopted as the image output unit 300,
Generally, the laser is turned on and off based on the result of comparison between the level of the triangular wave and the pixel value. Figure 1 shows the details
FIG. 5A to 5C show various triangular wave patterns. In these figures, TL indicates the level of the pixel value.

The image output unit 300 selects one of the triangular waves, turns on the laser beam when the pixel value TL is higher than the level of the selected triangular wave, and turns off the laser beam otherwise. In the section where the laser beam is turned on, the toner is fixed on the sheet, and the shapes of the sub-pixels corresponding to the respective triangular waves are as shown in FIGS.

Here, when the density of a pixel (not shown) adjacent to the pixel to be processed is 100%, a triangular wave is selected so that a sub-pixel continuous to the pixel is output. For example, if a 100% density pixel exists to the left of the target pixel, the triangular wave must be as shown in FIG. If the triangular wave shown in (b) or (c) is selected, a problem occurs in that the outline of a character or a line drawing is doubled.

<2-1-2: Raster data hollowing-out process> In some cases, text or line drawings are output on the background of raster data such as various photographs and pictures. One example will be described with reference to FIG. FIG. 7A shows original image data in which the character “SA” is superimposed on square blue raster data. The primary color of the image output unit 300 is K
(B)-(e) show the contents of each primary color plane when (black), Y (yellow), M (magenta), and C (cyan).
Since the character color is "black", the primary color is only K color. The raster data is “blue”, and the primary colors are M and C.

Here, in FIGS. 9D and 9E, an area of the raster data that overlaps with the character is previously subjected to a blanking process so as to be colorless. This is to prevent the color tone of the character portion from being destroyed when the character or line drawing and the raster data are output in a superimposed manner.

<2-1-3: Problem at Boundary Part> FIG.
Shows original image data in which black (pixel value = 255) characters are drawn over gray raster data (pixel value = 64). 21 (a) and 21 (b) are enlarged views of a boundary portion between the character and the raster data in FIG. In FIG. 9A, the density of the pixels in the outline portion of the character is 100%. On the other hand, in FIG.
The density of these pixels is 50%.

FIGS. 21C and 21D show the results of forming the sub-pixels described with reference to FIG. 18 on these original image data. No particular problem is seen in FIG. 9C, but in FIG. 9D, all sub-pixels at the boundary between the raster data and the character are biased to the right. This is because the pixels in the outline need to be connected to the 100% density pixels on the right side, and the triangular wave in FIG. 18C is always selected.

Therefore, in the output result of FIG.
There is a problem that a white outline is generated at the boundary between the character and the raster data. Although the example of FIG. 21 describes the case where the original image data is monochrome, the same applies to a case where color image data is output by a monochrome printer and a case where color image data is output in a monochrome mode of a color printer. Further, even when the color image data is output in the color mode of the color printer, if the characters and the like and the raster data have the same primary color, the same problem occurs in the primary color.

<2-2: Configuration and Operation of Embodiment> The configuration and operation of this embodiment are the same as those of the first embodiment. However, since the routine for determining whether to perform binary expansion or multi-level expansion on character or line drawing output is different from that in the first embodiment, these routines will be described.

<2-2-1: Determination of Character Expansion Method> In this embodiment, when the processing proceeds to step S103 in the main routine (FIG. 7), the routine shown in FIG. 22 is called. In the figure, the processing is step S501.
Then, it is determined whether or not the character to be expanded overlaps the raster data. If “NO” is determined here, the process proceeds to step S201 in FIG. 8, and the same process as in the first embodiment is performed. In such a case, the problem described with reference to FIG. 21 does not occur.

On the other hand, if "YES" is determined, the process proceeds to step S502, where a raster data centering process is performed. The details are as described in FIG. Next, when the process proceeds to step S503, it is determined whether the character to be expanded and the raster data have the same primary color. If “NO” is determined here, the process proceeds to step S201 in FIG. 8, and the same process as in the first embodiment is performed. Even if characters and raster data overlap, the primary color planes are different,
This is because the problem described in 1 does not occur.

If "YES" is determined in the step S503, the process proceeds to a step S504. Here, it is determined whether the density of the raster data is equal to or higher than a predetermined value. Here, if “NO” is determined, the process also proceeds to step S201 in FIG. In such a case, FIG.
Even if the problem described in 1 occurs,
If the density of the raster data is low, it is not conspicuous and is accepted. Note that this "predetermined value" may be determined according to the development characteristics of the printer.

If "YES" is determined in the step S504, application of the binary expansion is determined. As a result, the boundary between the character and the raster data is always shown in FIG.
As shown in (c), it is possible to prevent such a problem that a white outline is generated at the boundary portion as shown in (d) of FIG.

<2-2-2: Determination of Line Drawing Development Method> In the main routine (FIG. 7), the processing is
Even if the process proceeds to step 104, the above-described step S1
The same processing as in the case of 03 is performed. However, when determining the line drawing development method, steps S501 and S501
If “NO” is determined in 503 or S504, the process proceeds to step S301 in FIG.

In this way, when the primary colors of the line drawing and the raster data overlap and the density of the raster data is equal to or more than a predetermined value, the binary expansion is applied as in the case of the character,
Otherwise, the expansion method is determined by the same processing as in the first embodiment.

<3: Application Example> In the above-described embodiment, whether to binarize or multi-value for each object is determined. However, the present invention is not limited to this.
For example, whether to binarize or multi-value may be determined for each page or for the entire document. In this case, the development time of the character is predicted (step S202).
For, by treating the total number of characters present on the page (the number of character objects) or the total number of characters present in the document as an element such as the outline control score, The time required to expand all or the time required to expand all the characters present in the document can be estimated. Similarly, the development time of the line drawing is predicted (step S
302), the total number of line drawings existing on the page (the number of line drawing objects) or the total number of line drawings present in the document is treated as an element such as the length of the line drawing. It is possible to predict the time required to develop all the line drawings to be rendered or the time required to develop all the line drawings existing in the document.

Further, in the embodiment, all the discriminating conditions of FIG. 8 or 9 are executed, but these discriminating conditions do not necessarily have to be executed. . That is, it is desirable that these determination conditions are appropriately combined in accordance with the conditions, the environment, and the like.

[0082]

As described above, according to the present invention, P
When developing code image data such as DL into drawing pattern data as image data, anti-aliasing processing is performed as necessary, so that a large-capacity memory is not required and processing time is reduced. In addition to shortening, it is possible to generate high-quality drawing pattern data with less noticeable jaggies.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an entire system including an image processing unit according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a hardware configuration of the image processing unit.

FIG. 3 is a block diagram illustrating a functional configuration of the image processing unit.

FIGS. 4A and 4B are examples of screens displayed when multi-value expansion is designated by an operation panel or a host computer, respectively.

FIG. 5 is a diagram showing an example of the contents of a font table in the image processing unit.

FIG. 6 is a diagram showing an example of the contents of a character code table in the image processing unit.

FIG. 7 is a flowchart illustrating a main operation of the image processing unit.

FIG. 8 is a flowchart showing an operation when a character output is requested in the image processing unit.

FIG. 9 is a flowchart illustrating an operation when a line drawing is requested to be output in the image processing unit.

FIG. 10 is a flowchart illustrating an operation when a character output is requested in the image processing unit.

FIG. 11 is a diagram for explaining hint information.

FIGS. 12A to 12D are diagrams for explaining a character expanding operation in the same image processing unit.

FIG. 13 is a diagram for explaining an angle of a line in the image processing unit.

FIG. 14 is a diagram for explaining the width or length of a line in the image processing unit.

FIG. 15 is a diagram for explaining the width or length of a line in the image processing unit.

FIGS. 16A to 16E are diagrams for explaining conventional binary expansion and multi-level expansion, respectively.

FIGS. 17 (a) to (c) are diagrams for explaining conventional problems.

FIG. 18 is an explanatory diagram of a sub-pixel output method.

FIG. 19 is a diagram illustrating an example of a graphic in which raster data and characters overlap.

FIG. 20 is a diagram illustrating an example of a graphic in which raster data and characters overlap in the same color component.

21 is an enlarged view of FIG. 20 and an enlarged view of an output result after expanding FIG. 20 into sub-pixels.

FIG. 22 is a flowchart illustrating an operation when a character output request is made in the second embodiment.

[Explanation of symbols]

100 ... host computer (instruction means), 200 ...
… Image processing unit, 201… CPU (each unit), 205…
... operation panel (instruction means), 206 ... image storage unit (synthesis means), 251 ... code image data storage unit, 252
...... Expansion method determination unit (character discriminating means, line drawing discriminating means, first predicting means, second predicting means, comparing means), 253 ...
... Expansion method selection section (selection means), 254... Binary expansion section (first expansion means, identification data generation means), 255.
Multi-value expansion unit (second expansion unit, identification data generation unit),
300 image output unit (output means)

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroyuki Kono 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. (56) References JP-A-1-142983 (JP, A) JP-A-60-125061 ( JP, A) JP-A-8-235346 (JP, A) JP-A-1-292422 (JP, A) JP-A-1-133744 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09G 5/00-5/40 G09T 1/00-7/60 G06F 15/72-15/72 465

Claims (17)

(57) [Claims] 1. An image processing apparatus for expanding code image data into drawing pattern data, comprising: first expanding means for expanding the code image data into binarized drawing pattern data; Second developing means for developing into multi-valued drawing pattern data; condition determining means for determining whether the code image data is data corresponding to a predetermined condition; and Developing means for expanding the code image data by using the first or second
And a selecting means for selecting and applying any one of the developing means. 2. The image processing apparatus according to claim 1, wherein the code image data includes data relating to a character, and the condition determining unit includes a character determining unit;
Means, data relating to the character is determined whether or not the data corresponding to a predetermined condition related to the character Monodea
The image processing apparatus according to claim 1, wherein the selecting unit selects a developing unit to be applied based on a result of the determination by the character determining unit. Wherein the character for a given condition, an image processing apparatus according to claim 2, characterized in that it comprises a condition regarding font characters to be drawn. Wherein said character for a given condition, an image processing apparatus according to claim 2, characterized in that it comprises a condition related to the character size to be drawn. Wherein said character for a given condition, an image processing apparatus according to claim 2, characterized in that it comprises a condition relating to character codes to be drawn. 6. The image processing apparatus according to claim 2, wherein the predetermined condition regarding the character includes a condition regarding a color component of a character to be drawn and a color component of a background portion of the character. 7. The image processing apparatus according to claim 1, wherein the code image data includes data relating to a line drawing, and the condition determining unit includes a line drawing determining unit.
Means, data relating to the line drawings is determined whether or not the data corresponding to a predetermined condition related to a line drawing Monodea
The image processing apparatus according to claim 1 , wherein the selecting unit selects a developing unit to be applied based on a determination result of the line drawing determining unit. 8. The image processing apparatus according to claim 7, wherein the predetermined condition relating to the line drawing includes a condition relating to a length or a width of the line drawing to be drawn. 9. The image processing apparatus according to claim 7, wherein the predetermined condition relating to the line drawing includes a condition relating to an angle of the line drawing to be drawn. 10. The image processing apparatus according to claim 7, wherein the predetermined condition relating to the line drawing includes a condition relating to a color component of the line drawing to be drawn and a color component of a background portion of the line drawing. 11. The image processing apparatus according to claim 1, further comprising: a predicting unit configured to predict a time required for developing the code image data, wherein the second developing unit includes a predicting unit that predicts a time required for developing the code image data. Based on the prediction results,
An image processing apparatus for selecting a developing unit to be applied. 12. The image processing apparatus according to claim 1, further comprising: first predicting means for predicting a time required for the first developing means to develop the code image data; and A second prediction unit that predicts a time required for developing the code image data, a comparison unit that compares a prediction result obtained by the first prediction unit, and a prediction result obtained by the second prediction unit; The means is based on a comparison result of the comparing means,
An image processing apparatus for selecting a developing unit to be applied. 13. The method according to claim 13 , wherein said selecting means is said second developing means.
The provided with prohibiting means for prohibiting to select, and a instructing means for instructing to disallow expansion by the second developing means, said inhibiting means, based on the instruction of the instruction means, wherein the image processing apparatus according to claim 1, wherein the prohibiting selection of the second developing means. 14. The image processing apparatus according to claim 1, further comprising: synthesizing means for synthesizing the drawing pattern data expanded by the first and second expanding means; and drawing pattern data synthesized by the synthesizing means. But,
An image processing apparatus, comprising: identification data generating means for generating identification data indicating which of the first and second developing means has been developed. 15. The image processing apparatus according to claim 14, wherein the drawing pattern data synthesized by the synthesizing means is
Output means for outputting in accordance with the identification data generated by the identification data generation means. 16. An image processing method for expanding code image data into drawing pattern data, comprising: a first expanding step of expanding the code image data into binarized drawing pattern data; A second development process of developing the image data into the converted drawing pattern data; a condition determination process of determining whether or not the code image data is data satisfying a predetermined condition; and the code based on the determination in the condition determination process. A selection step of selecting and applying one of the first and second development steps as a development step of expanding the image data; and the drawing pattern data developed by the development step selected in the selection step. An image processing method, comprising: a combining step of combining. 17. A recording medium storing an image processing program for developing code image data into drawing pattern data by a computer, wherein the image processing program instructs the computer to execute the code image data under a predetermined condition. It is determined whether or not the data is applicable, and the user is allowed to select whether to develop into binarized drawing pattern data based on the determination or to develop into multi-valued drawing pattern data. A recording medium having recorded thereon an image processing program for combining the drawn pattern data.