JP3974700B2 - Image forming apparatus and image processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus and an image processing method for performing optimal image processing, an image forming apparatus such as a copying machine and a printer including the image processing apparatus, and a control method thereof.
[0002]
[Prior art]
In recent years, in copiers and printers, in order to output text and photos with high image quality, for example, processing with different filter coefficients is performed for text and photos, and simple binarization that effectively expresses structural information. Adaptive image processing that matches the properties of the image is performed, such as switching between dither processing that effectively expresses the processing and gradation information.
[0003]
As a process for identifying a character or a photograph, there is an identification process mainly focusing on edge information. There is also a process for identifying halftone dots using frequency information.
[0004]
Character quality is especially important for copiers, so the character is made darker by using the above identification results, and in the case of color copiers, characters are output using only black ink to increase the contrast of the characters. The improvement of visibility has been achieved.
[0005]
However, in the case of a bitmap image, it is not possible to completely identify characters and photographs, so correction for the identification result is important. As a technique that meets this requirement, for example, there is one disclosed in the following document.
[0006]
Reference 1: Shinichi Wakahara, JP 3-76377
Reference 2: Joe Suzuki, JP 63-40465
Reference 3: Yuki Uchida et al., JP-A-7-273993
The method disclosed in Document 1 extracts the contour of an image and corrects the inside of the extracted contour as a character.
[0007]
The method disclosed in Document 2 uses a region determination window after determining a binary image region (corresponding to characters) and a multi-value image region (corresponding to a halftone such as a photograph) of an image. By rescanning the image, the sum of the density values of the binary image area in the window is compared with the sum of the density values of the multi-value image area, and the discrimination result is corrected according to the comparison result.
[0008]
The method disclosed in Document 3 designates the degree of emphasis on character / line drawing and halftone, and the extraction parameters and determination results of the character / line drawing outline information, thickness information, and saturation information of the character / line drawing judging means are determined. Control is performed according to the degree of importance, and a black character correction image preferable for the user is obtained.
[0009]
[Problems to be solved by the invention]
Specifically, the method disclosed in Document 1 re-determines a pixel adjacent to the contour line inside the extracted contour line as a contour by using pattern matching, and the pixel adjacent to the contour line. However, there is a possibility that a line drawing that is only one pixel or a few pixels away from the contour line may be erroneously corrected as a contour line.
[0010]
The method shown in Document 2 is a correction that uses an image signal in addition to the identification result, so that the correction accuracy is improved over that of Document 1, but the circuit scale of a memory or the like is used because the image is rescanned or a window is used. As a result, the cost increases and the internal correction area is limited to the window size.
[0011]
The method shown in Document 3 is a window that includes a target thickness for determining the thickness, although black text processing according to the thickness of the character is performed according to the user's request, such as a copy mode. Therefore, there is a problem that the processing becomes complicated.
[0012]
That is, in the conventional example, in order to identify the inside of the character / line drawing outline information as a character / line drawing, a reference area corresponding to the thickness of the character / line drawing is required. Therefore, there is a problem that the circuit scale increases when the resolution of the printer is increased. Also, in order to improve the image quality according to the user's wish without affecting other images, it is necessary to make corrections according to the character density as well as the character thickness. As described above, there is a problem that high-accuracy correction cannot be performed on characters that are difficult to distinguish from gradation images.
[0013]
The present invention takes the above-mentioned circumstances into consideration, and the object of the present invention is to increase the quality of the circuit while eliminating the adverse effects on the gradation image as much as possible without increasing the circuit scale and the associated cost. An object of the present invention is to provide an image processing apparatus capable of outputting a character image.
[0017]
[Means for Solving the Problems]
  According to a first aspect of the present invention, there is provided an image forming apparatus that reads a document as multi-valued color image data and outputs RGB signals, and an RGB / CMY conversion unit that converts RGB signals of the color scanner section into CMY signals. The RGB / CMY conversion means takes in the CMY signal and generates a density signal, and outputs the density signal and the CMY signal as color signals, and the color signal output from the signal generation means An identification means for extracting an edge from each of a plurality of color images based on the image and outputting an identification signal representing the edge area and the non-edge area; A determination unit configured to determine whether the density is equal to or higher than a predetermined value, and the determination among the non-edge regions by the identification signal of the identification unit; In addition to having expansion means for expanding an area in which the image density is determined to be greater than or equal to a predetermined value to an edge area, the processing result of the expansion means for all four signals of the color signal is discriminated and corrected in the character mode. In the character / photo mode, the processing result of the expansion means for only the density signal of the color signal and the identification signal of the identification means for the CMY signal of the color signal are selected as identification correction signals in the character / photo mode, In the mode, the color correcting unit corrects the color signal based on the identification correction signal of the identification correction unit and a selection correction unit that selects the identification signal of the identification unit as the identification correction signal for all four signals of the color signal. Image correcting means for obtaining a C′M′Y′K signal for color printing;Is provided.
[0018]
  An image processing method according to a second aspect of the present invention includes a step of reading an original as multi-value color image data and outputting an RGB signal, a step of converting the RGB signal into a CMY signal, and a density signal obtained by taking the CMY signal. And outputting the density signal and the four CMY signals as color signals, extracting edges for each of a plurality of color images based on the color signals, and identifying signals representing edge regions and non-edge regions. And a step of determining whether the image density of the non-edge region based on the identification signal is equal to or higher than a predetermined value corresponding to the character region. In addition to performing a process of expanding an area that is determined to be greater than or equal to a predetermined value to an edge area, The result of the expansion process for all four signals is selected as an identification correction signal, and in the character / photo mode, the result of the expansion process only for the density signal of the color signal and the CMY signal of the color signal The identification signal is selected as an identification correction signal, and in the photo mode, the identification signal for all four signals of the color signal is selected as an identification correction signal, and the color signal is corrected based on the identification correction signal. And obtaining a C′M′Y′K signal for color printing.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0037]
FIG. 1 is a sectional view showing the internal structure of a digital copying machine as an example of the image forming apparatus of the present invention.
[0038]
In the main body 10 of the digital copying machine, a scanner unit 4 that functions as a reading unit and a printer unit 6 that functions as an image forming unit are provided.
[0039]
On the upper surface of the apparatus main body 10, a document placing table 12 made of transparent glass on which a reading object, that is, a document D is placed, is provided. Further, an automatic document feeder 7 (hereinafter referred to as ADF) for automatically feeding a document onto the document table 12 is disposed on the upper surface of the apparatus body 10. The ADF 7 is disposed so as to be openable and closable with respect to the document placing table 12, and also functions as a document presser that brings the document D placed on the document placing table 12 into close contact with the document placing table 12.
[0040]
The ADF 7 includes a document tray 8 on which a document D is set, an empty sensor 9 that detects the presence or absence of a document, a pickup roller 14 that picks up a document from the document tray 8 one by one, a paper feed roller 15 that transports the retrieved document, a document Are provided with an aligning roller pair 16 for aligning the leading ends of the paper and a conveying belt 18 disposed so as to cover almost the entire document placing table 12. Then, a plurality of originals set on the original tray 8 are taken out in order from the lowest page, that is, the last page, aligned by the aligning roller pair 16, and then placed on the original by the conveying belt 18. It is transported to a predetermined position on the table 12.
[0041]
In the ADF 7, a reversing roller 20, a non-reversing sensor 21, a flapper 22, and a paper discharge roller 23 are disposed at the end opposite to the aligning roller pair 16 with the conveying belt 18 in between. A document D whose image information has been read by a scanner unit 4 to be described later is sent out from the document placing table 12 by a conveyor belt 18 and is discharged from the upper surface of the ADF 7 via a reverse roller 20, a flapper 21, and a discharge roller 22. It is discharged on the part 24. When reading the back side of the document D, the document D transported by the transport belt 18 is reversed by the reversing roller 20 by switching the flapper 22, and then is again moved to a predetermined position on the document placing table 12 by the transport belt 18. Sent.
[0042]
The scanner unit 4 disposed in the apparatus main body 10 includes an exposure lamp 25 serving as a light source for illuminating the document D placed on the document table 12 and a first light that deflects reflected light from the document D in a predetermined direction. The exposure lamp 25 and the first mirror 26 are attached to a first carriage 27 disposed below the document table 12.
[0043]
The first carriage 27 is arranged to be movable in parallel with the document placing table 12 and is reciprocated below the document placing table 12 by a drive motor via a toothed belt (not shown).
[0044]
A second carriage 28 that is movable in parallel with the document table 12 is disposed below the document table 12. Second and third mirrors 30 and 31 for sequentially deflecting the reflected light from the document D deflected by the first mirror 26 are attached to the second carriage 28 at right angles to each other. The second carriage 28 is driven with respect to the first carriage 27 by a toothed belt or the like that drives the first carriage 27, and the document is placed on the first carriage at half the speed. It is moved in parallel along the table 12.
[0045]
Further, below the document table 12, an imaging lens 32 that focuses the reflected light from the third mirror 31 on the second carriage 28, and a reflected light focused by the imaging lens is received and photoelectrically received. A CCD sensor 34 for conversion is provided. The imaging lens 32 is disposed so as to be movable via a drive mechanism in a plane including the optical axis of the light deflected by the third mirror 31, and moves itself to reflect light at a desired magnification. Form an image. The CCD sensor 34 photoelectrically converts the incident reflected light and outputs an electrical signal corresponding to the read original D.
[0046]
On the other hand, the printer unit 6 includes a printer engine 40 that functions as a latent image forming unit. The printer engine 40 has laser generating means, for example, a semiconductor laser oscillator, continuously deflects a laser beam emitted from the laser oscillator and guides it to a photosensitive drum 44 described later, and exposes the peripheral surface of the photosensitive drum 44 by exposure scanning. As a result, an electrostatic latent image corresponding to the image information of the document D read by the scanner unit 4 and the facsimile transmission / reception document information is formed on the photosensitive drum 44.
[0047]
In addition, the printer unit 6 includes a rotatable photosensitive drum 44 as an image carrier disposed almost at the center of the apparatus main body 10, and the peripheral surface of the photosensitive drum 44 is a laser beam from the printer engine 40. Are exposed and scanned to form a desired electrostatic latent image. Around the photosensitive drum 44, a charging charger 45 for charging the drum peripheral surface to a predetermined charge, and toner as a developer is supplied to the electrostatic latent image formed on the peripheral surface of the photosensitive drum 44 to obtain a desired charge. A developing unit 46 that develops at an image density, a transfer material fed from a later-described paper cassette, that is, a peeling charger 47 for separating the copy paper P from the photosensitive drum 44 are integrally provided. A transfer charger 48 for transferring the toner image formed on the paper P to the paper P, a peeling claw 49 for peeling the copy paper P from the circumferential surface of the photosensitive drum 44, a cleaning device 50 for cleaning the toner remaining on the circumferential surface of the photosensitive drum 44, A static eliminator 51 for neutralizing the circumferential surface of the photosensitive drum 44 is disposed in order.
[0048]
In the lower part of the apparatus main body 10, an upper cassette 52, a middle cassette 53, and a lower cassette 54 that can be pulled out from the apparatus main body are arranged in a stacked state, and in each cassette, copy sheets having different sizes as image forming media are arranged. Is loaded. A large-capacity feeder 55 is provided on the side of these cassettes. The large-capacity feeder 55 stores about 3,000 sheets of frequently used copy paper P, for example, A4-size copy paper P. . A paper feed cassette 57 that also serves as a manual feed tray 56 is detachably mounted above the large capacity feeder 55.
[0049]
In the apparatus main body 10, a conveyance path 58 extending from each cassette and the large-capacity feeder 55 through a transfer portion located between the photosensitive drum 44 and the transfer charger 48 is formed. A fixing device 60 having a lamp 60a is provided. A discharge port 61 is formed in the side wall of the apparatus main body 10 facing the fixing device 60, and a single tray finisher 150 is attached to the discharge port 61. In the vicinity of the upper cassette 52, the middle cassette 53, the lower cassette 54, the paper feed cassette 57, and in the vicinity of the large-capacity feeder 55, pick-up rollers 63 for taking out the sheets P one by one from the cassette or the large-capacity feeder are provided. . The conveyance path 58 is provided with a number of paper feed roller pairs 64 that convey the copy paper P taken out by the pickup roller 63 through the conveyance path 58.
[0050]
A registration roller pair 65 is provided on the upstream side of the photosensitive drum 44 in the conveyance path 58. The registration roller pair 65 corrects the inclination of the taken copy paper P and aligns the leading edge of the toner image on the photosensitive drum 44 with the leading edge of the copying paper P so that the moving speed of the peripheral surface of the photosensitive drum 44 The copy paper P is fed to the transfer unit at the same speed. A pre-aligning sensor 66 for detecting the arrival of the copy paper P is provided in front of the registration roller pair 65, that is, on the paper feed roller 64 side.
[0051]
The copy paper P taken out one by one from each cassette or the large capacity feeder 55 by the pickup roller 63 is sent to the registration roller pair 65 by the paper feed roller pair 64. The copy paper P is fed to the transfer section after the leading edge is aligned by the registration roller pair 65.
[0052]
In the transfer portion, the developer image formed on the photosensitive drum 44, that is, the toner image is transferred onto the paper P by the transfer charger 48. The copy sheet P to which the toner image has been transferred is peeled off from the peripheral surface of the photosensitive drum 44 by the action of the peeling charger 47 and the peeling claw 49, and is transferred to the fixing device 60 via the conveyance belt 67 constituting a part of the conveyance path 52. Be transported. Then, after the developer image is melted and fixed on the copy paper P by the fixing device 60, the copy paper P is discharged onto the finisher 150 through the discharge port 61 by the paper feed roller pair 68 and the paper discharge roller pair 69.
[0053]
Below the conveyance path 58, there is provided an automatic duplex device 70 that reverses the copy paper P that has passed through the fixing device 60 and sends it again to the registration roller pair 65. The automatic double-side device 70 includes a temporary stacking unit 71 that temporarily stacks the copy paper P, and a reverse path 72 that branches from the conveyance path 58 and reverses the copy paper P that has passed through the fixing device 60 and guides it to the temporary stacking unit 71. A pick-up roller 73 for picking up the copy sheets P collected in the temporary stacking unit one by one, and a paper feed roller 75 for feeding the picked-up sheets to the registration roller pair 65 through the transport path 74. In addition, a branching gate 76 that selectively distributes the copy paper P to the discharge port 61 or the reversing path 72 is provided at a branch portion between the conveyance path 58 and the reversing path 72.
[0054]
When performing double-sided copying, the copy paper P that has passed through the fixing device 60 is guided to the reversing path 72 by the sorting gate 76 and is temporarily accumulated in the temporary accumulating unit 71 in an inverted state, and then the pickup roller 73 and The paper is fed to the registration roller pair 65 through the conveyance path 74 by the paper feed roller pair 75. Then, after the copy paper P is aligned by the registration roller pair 65, it is sent again to the transfer unit, and the toner image is transferred to the back surface of the copy paper P. Thereafter, the copy paper P is discharged to the finisher 130 via the conveyance path 58, the fixing device 60 and the paper discharge roller 69.
[0055]
The finisher 130 staples and stores the discharged partially structured document in units. Each time the copy paper P to be stapled is ejected from the single ejection port 61, the guide bar 131 moves toward the staple side and aligns. When all the paper has been discharged, the paper pressing arm 132 suppresses the partial copy paper P discharged, and a stapler unit (not shown) performs stapling. Thereafter, the guide bar 131 is lowered, and the copy paper P, which has been stapled, is discharged to the finisher discharge tray 134 by the finisher discharge roller 135 as a partial unit. The lowering amount of the finisher discharge tray 134 is determined to some extent by the number of copy sheets P to be discharged, and decreases step by step every time it is discharged in some units. Further, the guide bar 131 for aligning the discharged copy paper P is at such a height that it does not hit the already stapled copy paper P placed on the finisher discharge tray 134.
[0056]
Further, the finisher discharge tray 134 is connected to a shift mechanism (not shown) that shifts partly (for example, in four directions, front, rear, left, and right) in the sort mode.
[0057]
An operation panel for inputting various copy conditions and a copy start signal for starting a copy operation is provided at the upper front of the apparatus body 10.
[0058]
The control circuit is shown in FIG.
[0059]
The main CPU 91 of the main control unit 90 performs bidirectional communication with the printer CPU 110 via the shared RAM 95, the main CPU 91 issues an operation instruction, and the printer CPU 110 returns a status status.
[0060]
The printer CPU 110 of the printer unit 6 and the scanner CPU 100 of the scanner unit 4 perform serial communication, the printer CPU 110 issues an operation instruction, and the scanner CPU 100 returns a status status.
[0061]
A panel CPU 83 of the operation panel 80 is connected to the main CPU 91.
[0062]
The main control unit 90 includes a main CPU 91, ROM 92, RAM 93, NVM 94, shared RAM 95, image processing unit 96, page memory control unit 97, page memory 98, printer controller 99, and printer font ROM 121.
[0063]
The main CPU 91 controls the entire main control unit 90. The ROM 92 stores a control program. The RAM 93 temporarily stores data.
[0064]
An NVM (non-volatile RAM) 94 is a non-volatile memory backed up by a battery (not shown), and holds data on the NVM 94 when the power is turned off.
[0065]
The shared RAM 95 is used for bidirectional communication between the main CPU 91 and the printer CPU 110.
[0066]
The page memory control unit 97 stores or reads out image data in the page memory 98. The page memory 98 has an area where image data for a plurality of pages can be stored, and is formed so that data obtained by compressing image data from the scanner unit 4 can be stored for each page.
[0067]
The printer font ROM 121 stores font data corresponding to print data.
[0068]
The printer controller 99 converts print data from an external device 122 such as a personal computer into image data using font data stored in the printer font ROM 121 at a resolution corresponding to the data indicating the resolution given to the print data. It is something to deploy.
[0069]
The scanner unit 4 includes a scanner CPU 100 that controls the entire scanner unit 4, a ROM 101 that stores control programs and the like, a RAM 102 for storing data, a CCD driver 103 that drives a CCD sensor 34, an exposure lamp 25, and mirrors 26 and 27. , 28, etc., due to variations in the A / D conversion circuit and the CCD sensor 34 that converts an analog signal from the CCD sensor 34 to a digital signal or a change in ambient temperature. The image correction device 105 includes a shading correction circuit for correcting a change in the threshold level with respect to the output signal from the CCD sensor 34 and a line memory for temporarily storing the shading corrected digital signal from the shading correction circuit. It is.
[0070]
The printer unit 6 controls a printer CPU 110 that controls the entire printer unit 6, a ROM 111 that stores a control program, a RAM 112 for data storage, a printer engine 40 having a laser oscillator, and a conveyance path 58 for conveying the paper P. A paper transport device 115, a charging charger 45, a developing device 46, a developing process device 116 that performs charging, development, and transfer using a transfer charger 48, a fixing controller 117 that controls the fixing device 60, and an optional device 118. The
[0071]
The image processing unit 96, page memory 98, printer controller 99, image correction apparatus 105, and printer engine 40 are interconnected by an image data bus.
[0072]
As shown in FIG. 3, the image processing unit 96 is output from a line memory 1002 and a line memory 1002 that store image signals (multi-valued image signals) read by the scanner unit 4 in units of lines. An identification device 1003 for identifying an image contour so-called edge in block units based on the multi-valued image signal 1007 and outputting an identification signal 1008 representing an edge region and a non-edge region; The image correction apparatus 1005 corrects the multi-value image signal 1007 based on the identification correction signal (identification correction result) 1009 of the identification correction apparatus 1004. The output of the image correction apparatus 1005 is supplied to the printer engine 40.
[0073]
That is, the original image to be copied is read by the scanner unit 4 and converted into a multi-value image signal 1007 and held as a reference area pixel value in the line memory 1002. An edge of an image based on the multi-value image signal 1007 in the line memory 1002 is identified by the identification device 1003, and an identification signal 1008 representing the identification result is supplied to the identification correction device 1004.
[0074]
The identification correction device 1004 determines whether the image density of the non-edge area of the identification signal 1008 is equal to or higher than a predetermined value corresponding to the character area, and the image density is determined by the above-mentioned determination means of the non-edge area of the identification signal 1008. Conversion means for converting (expanding) an area determined to be equal to or greater than a predetermined value into an edge area. An identification correction signal 1009 that is an output of the identification correction device 1004 is supplied to the image correction device 1005.
[0075]
The image correction apparatus 1005 corrects the image density in the increasing direction as a predetermined process for an image corresponding to the edge region of the identification correction signal 1009 among the images based on the multi-value image signal 1007. A corrected image signal 1010 that is an output of the image correction apparatus 1005 is supplied to the printer engine 40.
[0076]
The multi-value image signal 1007 will be described below as being converted to a density signal (black is 255 level, white is 0 level), but even if it is a lightness signal (black is 0 level, white is 255 level). It operates in the same way just by inverting the logic.
[0077]
Here, the operation of the line memory 1002 will be described with reference to FIGS. As shown in FIG. 4, in order to refer to pixel values in a 3 × 3 matrix unit centered on the pixel b 1, the data inputted in the pixel unit is converted into the line memory A and the line memory B in the line unit of the scanner unit 4. , Sequentially stored in the line memory C for reference. If the data from the scanner unit 4 is sequentially stored in the line memory D, it can be referred to without stopping the operation of the scanner unit 4.
[0078]
After referring to the line memory B (b0, b1,... B9) as the center, as shown in FIG. 5, in order to refer to pixel values in a 3 × 3 matrix unit centered on the pixel c1, the line memories B, C, D If the data from the scanner unit 4 is stored in the line memory A during reading from the image data, the image data can be referred to without stopping the operation of the scanner unit 4.
[0079]
Next, the operation of the identification device 1003 will be described with reference to FIGS.
[0080]
As shown in FIG. 6, the identification device 1003 operates to extract the edge of the image. As a configuration, for example, as shown in FIG. 7, the difference between the maximum value and the minimum value in the 3 × 3 matrix is compared with a threshold value.
[0081]
The selector 1003-1 selectively outputs from the line memory 1002 the center line data of the 3 × 3 matrix as the signal 1007, the upper line data thereof as the signal 1003-2, and the lower line data as the signal 1003-3. For example, a 3 × 3 matrix centering on the pixel c1 in FIG. 5 will be described as an example. The signal 1003-2 corresponds to the line memory B, the signal 1007 corresponds to the line memory C, and the signal 1003-3 corresponds to the line memory D. Further, the signal 1003-2 can obtain outputs b 0, b 1, and b 2 through a D-FF (D-type flip-flop circuit). By passing the output of the selector 1003-1 through the D-FF, data of a 3 × 3 matrix centered on the c1 pixel can be input to the maximum value comparator 1003-4 and the minimum value comparator 1003-5.
[0082]
The maximum value comparator 1003-4 and the minimum value comparator 1003-5 compare the values of the input signals, respectively, and selectively output the maximum value and the minimum value. The difference between the maximum value and the minimum value is obtained by the differentiator 1003-6, and the difference is compared with the threshold value 1003-7 by the comparator 1003-8. The comparator 1003-8 sets “1” as an edge region having a large change if the output of the difference unit 1003-6 is larger than the threshold 1003-7, and “0” as a non-edge region having a small change if the output is small. Are output as identification signals 1008, respectively.
[0083]
Next, the operation of the identification correction apparatus 1004 will be described with reference to FIGS. 8, 9, 10, 11, 12, 13, and 14.
[0084]
As shown in FIG. 8, the identification correction device 1004 includes a character area determination unit 1004-1 as the determination unit and an identification expansion unit 1004-2 as the expansion unit.
[0085]
The character area discriminating unit 1004-1 includes a comparator 1004-5 shown in FIG. 9, and if the multi-value image signal 1007 is larger than the character threshold value 1004-4 (close to black), “1” is obtained, and if it is smaller, “0” is obtained. , And output as a character region discrimination signal 1004-3.
[0086]
As shown in FIG. 10, the identification expansion unit 1004-2 includes a counter 1004-6 that receives an identification signal 1008 and a character area determination signal 1004-3, an overflow memory 1004-7, and other control circuits. Is done.
[0087]
The identification correction signal 1009 is taken out as an OR circuit output of the identification signal 1008 and the identification internal correction signal 1004-2-1. The counter 1004-6 is a 3-bit counter having an input of + "1" addition (+1), forcibly "1" (= 1), and forcibly "0" (reset). The overflow memory 1004-7 forcibly holds “1” when the counter outputs are all “1” (= 1), and forcibly when the identification signal 1008 is “1” (edge of characters, etc.). It is a 1-bit memory that has an input of “0” (reset) and holds the other values. FIG. 11 shows the relationship between the counter input and output.
[0088]
As shown in the flowchart of FIG. 12, the operation of the identification expansion unit 1004-2 is performed as follows. The non-edge area that is in contact with the edge area that is determined as the character area is the edge area by a predetermined amount based on an upper limit value that is predetermined in one direction. Expand (convert) as In the flowchart of FIG. 12, the process of expanding the non-edge area as an edge area is referred to as converting the identification signal into an edge signal.
[0089]
That is, when there is an edge and the inside is a character area, the overflow memory 1004-7 is controlled to enter the identification correction mode, and the above processing is executed. The expansion amount is limited to a predetermined amount by the upper limit value set in the counter 1004-6.
[0090]
A specific example of image processing is shown in FIG. In the generation of the identification signal based on the edge, if there is a large density difference from the surrounding pixels, the edge is extracted regardless of the character image and the gradation image. In character area discrimination, since the character density is generally high, the density of the character image 2 and the gradation image 2 is set as a predetermined value, and an area with a higher density is extracted as the character area. Identification correction is performed on the character region inside the edge signal. Since the expansion is up to the upper limit value (here, the width of the character image 1 and the width of the character image 2) by the counter, the edges of the gradation image 1 and the gradation image 2 are slightly identified as characters. Keep the non-edge area state. In other words, when the inside of the edge is a character area, the area is definitely determined as a character area, and when the inside of the edge is a gradation image, the entire area is erroneously determined as a character area. .
[0091]
In the flowchart of FIG. 12, the counter is forcibly set to “1” when the identification correction mode is entered. As shown in FIG. 14, the identification signal 1008 is expanded by several pixels from the edge. This is because counting starts from the expanded edge signal and expands excluding the already expanded components. For this reason, the amount of expansion can be controlled with the same counter amount.
[0092]
FIG. 15 shows the process of the expansion of the identification signal expressed by input / output signals of each counter value. In the range A, the identification signal is completely filled because the upper limit of the counter is “7”. However, in the range B, the identification signal does not change beyond the upper limit “7” of the counter.
[0093]
Next, the image correction apparatus 1005 will be described with reference to FIGS. 16, 17, 18, and 19.
[0094]
The input image (character image) from the scanner unit 4 is blurred at the time of input as shown in FIG. 16, or in the case of a document output by an electrophotographic printer engine, the inside of the edge is thinner than the outside from before the input as shown in FIG. May be. However, it is better to output the originally uniform black characters in black without deterioration as in the output images shown in FIGS. 16 and 17, respectively. Therefore, as shown in FIG. 18, a dark and easy-to-see character output can be obtained by performing density increase correction for bringing the high density area of the area determined as a character close to the solid density.
[0095]
As a configuration, for example, an LUT (Look Up Table) 1005-1 shown in FIG. 19 and its peripheral circuits are adopted, and the conditions shown in FIG. 18 are given to the LUT (Look Up Table) 1005-1 as a conversion table. It is possible. The LUT 1005-1 outputs 8-bit data when a multi-value image signal (8 bits) 1007 is input as an address. Based on the identification correction signal 1009, either the output of the LUT 1005-1 or the multi-valued image signal 1007 is selected and output as a corrected image signal 1010.
[0096]
As described above, according to the first embodiment, since the area corresponding to the character in the non-edge area of the image is converted into the edge area, the circuit scale is increased and the cost is increased accordingly. A high-quality character image can be output without incurring the adverse effects on the gradation image as much as possible.
[0097]
In the first embodiment, it is configured to correct general black characters, that is, data having a large density value of the character area. However, by inverting the logic, the density values of the white area, that is, the character area is smaller than the surrounding area. Data may be corrected so that white characters are whiter and white characters having high contrast can be obtained.
[0098]
Next, as a second embodiment of the present invention, an example in which the identification correction apparatus 1004 of the first embodiment is configured by a character area determination unit 1004-1 and an identification expansion unit 1000041-2 shown in FIG. In this case, since only the identification expansion unit 1000041-2 is different from the first embodiment, the identification expansion unit 1000041-2 will be described below.
[0099]
As shown in FIG. 21, the identification expansion unit 1000041-2 is composed of a main scanning identification expansion unit 1000041-2-1 and a sub-scanning identification expansion unit 1000041-2-2. The OR circuit output of one main scanning identification correction signal 10091-1 and the sub-scanning identification correction signal 10091-2 of the sub-scanning identification expansion unit 1000041-2 becomes an identification correction signal 1009.
[0100]
The point is that the first embodiment performs expansion processing in one direction only in the main scanning direction of the scanner unit 4 as shown in FIG. 22, whereas in the second embodiment, as shown in FIG. The difference is that expansion processing is performed in a plurality of directions in the scanning direction and the sub-scanning direction. Thereby, it is possible to reduce the adverse effect on the gradation image while improving the image quality of the characters.
[0101]
The configuration of the main scanning identification expansion unit 1000041-2-1 is the same as that of the identification expansion unit 1000041-2 except that the output signal is input to the OR circuit together with the sub-scanning identification correction signal 10091-2. The sub-scanning identification expansion unit 10041-2-2 will be described with reference to FIGS.
[0102]
The basic configuration of the sub-scanning identification expansion unit 1000041-2-2 is the same as that of the identification expansion unit 1004-2, but in order to control the expansion amount in the sub-scanning direction, counter values for the number of main scanning pixels and Memory 1000041-2-2-1 for holding an overflow value, counter 1000041-2-2-2 capable of arbitrarily inputting / outputting a counter value and an overflow value, overflow memory 10041-2-2-3, and other circuits It consists of. The operation of the sub-scanning identification expansion unit 1000041-2-2 is shown in the flowchart of FIG. 25, whereas the main scanning identification expansion unit 1000041-2-1 resets the counter value and the overflow value only at the main scanning line start position. The sub-scanning identification expansion unit 10041-2-2 clears the memory and resets the counter value and the overflow value at the start of processing, and reads and stores the counter value and the overflow value from the memory every time one pixel is processed. The point is different.
[0103]
In the second embodiment, the example in which the expansion is performed in the main scanning direction and the sub-scanning direction is shown. Of course, the expansion is performed in the other main scanning reverse direction, the sub-scanning reverse direction, and the diagonal direction. However, it is possible to correct the character image with little influence on the gradation image.
[0104]
Next, as a third embodiment, a configuration in which the identification correction device 1004 and the image correction device 1005 of the first embodiment are replaced with the identification correction device 10042 and the image correction device 10052 shown in FIG.
[0105]
The configuration of the identification correction device 10044 is that the identification correction device 1004-2 shown in FIG. 10 merely outputs the identification signal 1008 and the identification internal correction signal 1004-2-1 separately without outputting them through an OR circuit. Yes, this is not shown. Only the image correction apparatus 10052 will be described with reference to FIGS. 27, 28, and 29. FIG.
[0106]
As shown in FIG. 27, the image correction apparatus 10052 includes an LUT (Look Up Table) 10052-1, a counter 10052-2, and other circuits. The contents of the LUT 10052-1 are the conditions shown in FIG. 18, for example. The operation is performed so that the output from the LUT 10052-1 is gradually subtracted while the identification internal signal 1004-2-1 continues, so as to approach the inclination when the condition conversion of FIG. 18 is not performed.
[0107]
For example, as shown in FIG. 29, when the identification internal correction signal 1004-2-1 is continuous, the probability of being a gradation image is increased, so that the effect of the correction on the gradation image is reduced. In the case of a character image, it is also subtracted. However, as shown in FIG. 28, the character image often has a high density, and when the electrophotographic method is used for the printer engine 40, the high density portion tends to be crushed. small.
[0108]
In the third embodiment, an example of simple subtraction is shown, but the subtraction amount is changed according to the multi-value image signal 1007, or the continuity of the identification internal correction signal 1004-2-1 is counted nonlinearly. It is also possible.
[0109]
In the third embodiment, the character area is continuously corrected from the edge area. However, when the non-correction area is provided in units of one pixel to several pixels as shown in FIG. Since the output density of the non-correction area surrounded by the correction area that is output darkly becomes slightly higher, the correction effect appears in dark characters, etc., and the output density does not fluctuate in lighter gradation areas. Can reduce the effects of
[0110]
That is, since the conditions for identification correction can be arbitrarily set by selecting various parameters, the character image quality can be improved in accordance with various conditions.
[0111]
Next, as a fourth embodiment of the present invention, it is conceivable to replace the character area determination unit 1004-1 of the identification correction apparatus 1004 of the first embodiment with a character area determination unit 10034-1 shown in FIG.
[0112]
As shown in FIG. 32, the character area discriminating unit 10034-1 takes the difference value from the previous pixel by the difference unit 10034-1-1 and compares it with the increase / decrease threshold value 10039-1-3 by the comparator 10043-1-2. To do. The comparison result is written into the memory 10034-1-4 only when the identification signal 1008 indicates an edge. An AND circuit output of the increase / decrease comparison result stored in the memory 1000043-1-4 and the comparison result of the comparator 1004-5 similar to that of FIG. 9 in the first embodiment is output as the character area signal 10004-3. The character area discriminating unit 10034-1 operates according to the processing flow shown in FIG. 33 by a control circuit (not shown).
[0113]
FIG. 34 shows examples of state changes of the multi-value image signal 1007, the identification signal 1008, the output of the memory 10034-1-4, the output of the comparator 1004-5, the character region signal 1004-3, and the identification correction signal 1009. Since the upper thin character is not distinguished from the character, an output without a decrease in contrast can be obtained. Here, the configuration is such that the identification signal 1008 rises at both ends of the edge and uses the increase / decrease state of the edge position of the identification signal 1008. However, as apparent from the embodiment, the density inside and outside the character is also shown. It is not limited to this example as long as the difference can be seen.
[0114]
Next, as a fifth example, it is conceivable to replace the identification expansion unit 1004-2 of the identification correction apparatus 1004 in the first example with an identification expansion unit 10044-2 shown in FIG.
[0115]
The identification expansion unit 10044-2 compares the output of the counter 1004-6 with the expansion upper limit value 1044-2-2 by the comparator 10044-2-1 and controls the expansion upper limit value 1044-2-2 instead of a fixed value. (The control circuit is not shown in the figure.) The expansion amount is arbitrarily controlled. For example, in a character mode generally provided in a copying machine (a clean output centered on characters), the expansion amount is maximized, and a character / photo mode (character The image quality can be adjusted to the user's specification by setting the expansion amount to “0” in the photo mode (clearly output centering on the photo). Can be done.
[0116]
Next, as a sixth embodiment, a configuration is possible in which an identification correction device 10045 having an identification expansion section 10045-2 as shown in FIG. 36 is used instead of the identification correction device 1004 of the first embodiment.
[0117]
In other words, the identification correction device 10045 is different from the first embodiment in that the identification expansion unit 10045-2 is also configured to capture the multi-value image signal 1007.
[0118]
As shown in FIG. 37, the identification expansion unit 10045-2 controls the expansion amount by the comparator 10045-2-1 as in the fifth embodiment. The difference from the fifth embodiment is that the expansion upper limit value 10045-2-2 is set not in the image mode but in multiple stages for each image density using the multi-value image signal 1007. For example, an expansion upper limit value 10045-2-2 shown in FIG. 38 is set in the LUT (Look Up Table) 10045-2-3, and control for increasing the expansion amount as the image density increases can be performed. Of course, the control of the expansion amount is not limited to the multi-value image signal 1007, but the LUT used for the mode signal may be switched using a plurality of LUTs 10045-2-3, or may be obtained by calculation from the LUT, without using the LUT. You may obtain | require by calculating from the multi-value image signal 1007. FIG.
[0119]
Next, as a seventh embodiment, instead of the identification correction device 1004 of the first embodiment, from a character area determination section 1004-1, an identification expansion section 1004-2, and an isolated identification correction section 10046-1 as shown in FIG. A configuration that employs the identification correction device 10046 is conceivable.
[0120]
That is, the identification correction device 10046 is different from the first embodiment in that the identification result 10086 corrected by the isolated identification correction unit 10046-1 is input to the identification expansion unit 1004-2 instead of the identification signal 1008.
[0121]
As shown in FIG. 40, the isolated identification correcting unit 10046-1 is composed of a plurality of D-FFs (D-type flip-flop circuits), an OR circuit, and an AND circuit. As shown in FIG. An isolated identification signal generated at an edge corresponding to a halftone dot region such as an image is removed to prevent erroneous image correction processing for characters on the halftone dot region.
[0122]
In the seventh embodiment, the determination is made based only on the identification signal 1008. However, the multi-value image signal 1007 may be used together.
Next, an example in which the present invention is applied to the color digital copying machine shown in FIG. 42 will be described as an eighth embodiment.
[0123]
The color digital copying machine includes a scanner unit 201 and a printer unit 202.
[0124]
The scanner unit 201 that reads an image has a document table cover 203 on the upper portion thereof, a document table 204 made of transparent glass on which the document is set, facing the document table cover 3 in a closed state. . Below the document table 204, an exposure lamp 205 for illuminating the document placed on the document table 204, a reflector 206 for collecting light from the exposure lamp 205 on the document, and reflected light from the document in the left direction in the figure A first mirror 207 and the like that are bent in the direction are arranged. The exposure lamp 205, the reflector 206, and the first mirror 207 are fixed to the first carriage 208. The first carriage 208 is connected to a pulse motor (not shown) via a toothed belt (not shown) and the like, and the driving force of the pulse motor is transmitted to move in parallel along the document table 204.
[0125]
The left side of the drawing with respect to the first carriage 208, that is, the direction in which the reflected light reflected by the first mirror 207 is guided, is parallel to the document table 204 via a driving mechanism (not shown) such as a toothed belt and a DC motor. A second carriage 209 is provided so as to be movable. The second carriage 209 includes a second mirror 211 that folds the reflected light from the document guided by the first mirror 207 downward, and a third mirror 212 that folds the reflected light from the second mirror 211 in the right direction in the drawing. They are arranged at right angles to each other. The second carriage 209 is driven by the first carriage 208 and is moved in parallel along the document table 204 at a half speed with respect to the first carriage 208.
[0126]
An imaging lens 213 that forms an image of the reflected light from the second carriage 209 at a predetermined magnification is disposed in a plane including the axis of the light reflected through the second carriage 209, and passes through the imaging lens 213. A CCD image sensor (photoelectric conversion element) 215 that converts the reflected light that is focused by the imaging lens 213 into an electric signal, that is, image data, is disposed in a plane that is substantially orthogonal to the light axis.
[0127]
Thus, when the light from the exposure lamp 205 is irradiated onto the document on the document table 204 by the reflector 206, the reflected light from the document is changed into the first mirror 207, the second mirror 211, the third mirror 212, and the imaging lens 213. Is incident on the CCD image sensor 215 via the image data and converted into image data of a plurality of colors.
[0128]
The printer unit 202 performs color separation for each color component based on a known subtractive color mixing method, that is, cyan (bluish purple, hereinafter referred to as C), magenta (a type of red, hereinafter referred to as M). ), Yellow (yellow, hereinafter referred to as “Y”), and black (black, hereinafter referred to as “K”), and first to fourth image forming portions 110y, 110m, 110c, and 110k that respectively form images. ing.
[0129]
Below each of the image forming units 110y, 110m, 110c, and 110k, a transport mechanism 120 serving as a transport unit including a transport belt 121 that transports an image of each color formed by each image forming unit in the direction of arrow a in the figure. It is arranged. The conveyor belt 121 is wound and stretched between a driving roller 191 that is rotated in the direction of arrow a by a belt motor (not shown) and a driven roller 192 that is a predetermined distance away from the driving roller 191, and has a constant speed in the direction of arrow a. And run endlessly. The image forming units 110y, 110m, 110c, and 110k are arranged in series along the conveyance direction of the conveyance belt 121.
[0130]
Each of the image forming units 110y, 110m, 110c, and 110k is a photosensitive drum 161y, 161m, 161c, and 161k as an image carrier having an outer peripheral surface that is formed to be rotatable in the same direction at a position in contact with the conveyance belt 121. Is included. A drum motor (not shown) for rotating each photosensitive drum at a predetermined peripheral speed is connected to each photosensitive drum.
[0131]
The axes of the respective photoconductive drums 161y, 161m, 161c, and 161k are arranged so as to be orthogonal to the direction in which the image is conveyed by the conveyance belt 121, and the axes of the respective photoconductive drums are arranged at equal intervals. In the following description, the axial direction of each photosensitive drum is the main scanning direction (second direction), and the direction in which the photosensitive drum is rotated, that is, the rotation direction of the conveying belt 121 (the direction of arrow a in the figure). The sub-scanning direction (first direction) is assumed.
[0132]
Around the photosensitive drums 161y, 161m, 161c, and 161k, charging devices 162y, 162m, 162c, and 162k as conductive means extended in the main scanning direction, static elimination devices 163y, 163m, 163c, and 163k, main scanning direction Similarly, the developing rollers 164y, 164m, 164c, 164k, the lower agitating rollers 167y, 167m, 167c, 167k, the upper agitating rollers 168y, 168m, 168c, 168k, similarly extending in the main scanning direction. Transfer devices 193y, 193m, 193c, and 193k as the transferred transfer means, cleaning blades 165y, 165m, 165c, and 165k that are similarly extended in the main scanning direction, and waste toner collection screws 166y, 166m, 166c, and 166k , Respectively, the corresponding photosensitivity They are arranged in this order along the rotating direction of the drum.
[0133]
Each transfer device is disposed at a position where the conveyance belt 121 is sandwiched between the transfer drum and the corresponding photosensitive drum, that is, inside the conveyance belt 121. Further, exposure points by an exposure device described later are formed on the outer peripheral surface of the photosensitive drum between the charging device and the developing roller, respectively.
[0134]
Below the transport mechanism 120, paper cassettes 122a and 122b containing several sheets of recording paper P as specific image forming media for transferring images formed by the image forming units 110y, 110m, 110c, and 110k are disposed. ing.
[0135]
Pick-up rollers 123a and 123b for picking up recording paper P stored in the paper cassettes 122a and 122b one by one (from the top) at one end of the paper cassettes 122a and 122b and close to the driven roller 192. Is arranged. Between the pickup rollers 123a and 123b and the driven roller 192, the leading edge of the recording paper P taken out from the paper cassettes 122a and 122b and the leading edge of the toner image formed on the photosensitive drum 161y of the image forming unit 110y are aligned. A registration roller 124 is provided for this purpose. The toner images (m, c, k) formed on the other photosensitive drums 161m, 161c, 161k are supplied to the respective transfer positions in accordance with the conveyance timing of the recording paper P conveyed on the conveyance belt 121. The
[0136]
Between the registration roller 124 and the first image forming unit 110y, in the vicinity of the driven roller 192, substantially on the outer periphery of the driven roller 192 with the conveyance belt 121 interposed therebetween, a predetermined roller via the registration roller 124 is provided. A suction roller 126 that provides a predetermined electrostatic suction region is disposed on the recording paper P that is transported three times at the same timing. Note that the axis of the suction roller 126 and the axis of the driven roller 192 are arranged in parallel to each other.
[0137]
One end of the conveyance belt 121, in the vicinity of the driving roller 191, substantially on the outer periphery of the driving roller 191 with the conveyance belt 121 interposed therebetween, is for detecting the position of the image formed on the conveyance belt 121. A misalignment sensor 196 is disposed at a predetermined distance from the drive roller 191. The positional deviation sensor 196 is configured by a transmissive or reflective optical sensor.
[0138]
A conveyor belt cleaning device 195 that removes toner adhering to the conveyor belt 121 or paper dust of the recording paper P is disposed on the conveyor belt 121 on the outer periphery of the driving roller 191 and downstream of the positional deviation sensor 196. Has been.
[0139]
In the direction in which the recording paper P transported via the transport belt 121 is separated from the driving roller 191 and further transported, the toner image transferred to the recording paper P is melted by heating the recording paper P to a predetermined temperature. In addition, a fixing device 180 for fixing the toner image on the recording paper P is disposed. The fixing device 180 includes a heat roller 181, oil application rollers 182 and 183, a web winding roller 184, a web roller 185, and a web pressing roller 186. The toner formed on the recording paper P is fixed on the recording paper, and is discharged by the paper discharge roller pair 187.
[0140]
A color printer engine 150 that forms an electrostatic latent image that is color-separated on the outer peripheral surface of each photoconductor drum is provided with image data (y, m, c, k) for each color that is color-separated by an image processing apparatus described later. ) Based on the semiconductor laser 160 whose emission is controlled. On the optical path of the semiconductor laser 160, the polygon mirror 151 rotated by the polygon motor 154 that reflects and scans the laser beam, and the focus of the laser beam reflected through the polygon mirror 151 are corrected and imaged. The fθ lenses 152 and 153 are provided in order.
[0141]
Between the fθ lens 153 and the photosensitive drums 161y, 161m, 161c, and 161k, a first folding mirror that bends the laser beam for each color that has passed through the fθ lens 153 toward the exposure position of each photosensitive drum. 155 (y, m, c, k) and second and third folding mirrors 156 (y, m, c), 157 for further folding the laser beam folded by the first folding mirrors 155y, 155m, 155c (Y, m, c) are arranged. The black laser beam is returned by the first return mirror 155k and then guided to the photosensitive drum 161k without passing through another mirror.
[0142]
The control circuit is shown in FIG.
[0143]
The control circuit includes a scanner unit 201 and a printer unit 202 instead of the scanner unit 4 and the printer unit 6 of the first embodiment, and the printer unit 202 includes a color printer engine 150.
[0144]
As shown in FIG. 44, the image processing unit 96 includes an RGB / CMY conversion device 2002, a line memory 2003, a signal generation device 2004, an identification device 2005, an identification correction device 2006, an inking device 2007, an image correction, and the like. A device 2008 is provided.
[0145]
That is, the scanner unit 201 irradiates the original with light and reads the reflected light with a CCD having RGB color filters, thereby reading the original as multi-value color image data. The RGB / CMY conversion device 2002 converts the RGB signal from the scanner unit 201 into a CMY signal (the amount of ink output by the color printer engine 150). In general, the color range to be reproduced differs between the color space of the original obtained by reading by the scanner unit and the color space represented by the ink amount, and the latter has a narrower color reproduction range. Therefore, the RGB / CMY conversion device 2002 converts the input color reproduction range into a signal that can be expressed by the ink amount CMY, for example. This technique is called color correction and performs non-linear conversion. The range of values to be converted is 0 ≦ C, M, and Y ≦ 255.
[0146]
The line memory 2003 holds data generated in units of lines by the scanner unit 201 in the same manner as in the first embodiment, except that the number of signals is increased from one signal to three signals.
[0147]
As shown in FIG. 45, the signal generation device 2004 takes in the CMY signal (three signals) 2010 to newly generate a density signal (or brightness signal), and combines the density signal and the CMY signal 2010. The signal is output as a color signal 2011. The density signal is obtained, for example, by the calculation shown in the following expression by the calculator 2004-1.
[0148]
Density signal = (C + M + Y) ÷ 3
Similarly, the discriminating apparatus 2005 is different from the first embodiment in that the processing performed on one signal in the first embodiment is performed on four signals of the color signal 2011, and outputs an identification signal 2012 for the four signals.
[0149]
Similarly, the identification correction device 2006 is different from the first embodiment in that it performs processing on four signals of the color signal 2011, which is performed on one signal in the first embodiment. As shown in FIG. 1 outputs a character area discrimination signal 2006-4 for four signals, and a discrimination expansion unit 2006-2 outputs a discrimination expansion signal 2006-5 for the four signals. Further, the selector 2006-3 selects either the identification expansion signal 2006-5 or the identification signal 2012 and outputs it as the identification correction signal 2013.
[0150]
For example, the selector 2006-3 selects the identification expansion signal 2006-5 for all four signals in the character mode and outputs it as the identification correction signal 2013. In the character / photo mode, the selector 2006-3 identifies only the density signal. When the signal 2006-5 is selected, the identification signal 2012 is output as the identification correction signal 2013 for the other CMY signals, and the identification signal 2012 for all four signals is output as the identification correction signal 2013 in the photo mode. That is, the output related to the image of the predetermined color is selected according to the determination result of the character region determination unit 2006-1 from the output of the expansion processing of the identification expansion unit 2006-2.
[0151]
In this embodiment, the signal for arbitrarily performing the identification correction is selected by the selector. However, as described in each embodiment, the threshold value of the character area determination unit is changed according to the type of the image signal, or the expansion of the identification expansion unit is performed. Naturally, a configuration for controlling the amount is also conceivable.
[0152]
The inking device 2007 generates the black signal K using only the CMY signal among the color signals 2011 (CMY + density signal), and changes the CMY value in accordance with the addition of the black signal K. As a result, a C′M′Y′K signal is obtained. In this example, the C′M′Y′K signal is obtained by the following formula, but the present invention is not limited to this.
[0153]
K = min (C, M, Y)
C ′ = C−K
M ′ = M−K
Y '= Y-K
Similarly, the image correction apparatus 2008 is different in that what is performed on one signal in the first embodiment is performed on the C′M′Y′K signal (four signals) 2014. At this time, among the identification correction results included in the identification correction signal 2013, the identification correction result corresponding to the density signal is directly applied to the K signal.
[0154]
As described above, since the identification signal and the identification correction signal are generated using the density signal approximated to the K signal before the K signal is generated by the inking process, C′M′Y ′ having a large variation due to the inking process is generated. Since an accurate identification signal can be obtained from the K ′ signal, the image quality by correction can be improved, and by selecting the identification correction signal, the range of image quality selection by mode processing or the like can be expanded.
[0155]
【The invention's effect】
  As mentioned above, thisinventionAccording to,An image processing apparatus capable of outputting a high-quality character image without causing an adverse effect on the gradation image as much as possible without causing an increase in circuit scale and associated cost increaseAnd image processing methodCan provide.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the overall configuration of first to seventh embodiments of the present invention.
FIG. 2 is a block diagram showing a configuration of a control circuit according to first to seventh embodiments.
FIG. 3 is a block diagram illustrating a configuration of an image processing unit according to the first and second embodiments.
4 is a diagram for explaining the operation of the line memory in FIG. 3; FIG.
FIG. 5 is a diagram for explaining the operation of the line memory together with FIG. 4;
6 is a diagram for explaining the operation of the identification device in FIG. 3; FIG.
7 is a block diagram showing the configuration of the identification device in FIG. 3;
8 is a block diagram showing a configuration of the identification correction apparatus in FIG. 3;
9 is a block diagram showing a configuration of a character area determination unit in FIG. 8. FIG.
10 is a block diagram showing a configuration of an identification expansion unit in FIG. 8. FIG.
FIG. 11 is a view for explaining the processing in FIG. 10;
12 is a flowchart for explaining the operation of FIG. 8;
13 is a diagram for explaining the image processing of FIG. 8;
14 is a diagram for explaining the discrimination function of FIG. 8; FIG.
FIG. 15 is a time chart for explaining identification correction in FIG. 8;
FIG. 16 is a diagram for explaining blur input as an example of processing of the image correction apparatus according to the first embodiment;
FIG. 17 is a diagram for explaining photographic input as an example of processing of the image correction apparatus according to the first embodiment;
FIG. 18 is a diagram illustrating processing conditions of the image correction apparatus according to the first embodiment.
FIG. 19 is a block diagram showing the configuration of the image correction apparatus according to the first embodiment.
FIG. 20 is a block diagram showing a configuration of an identification correction apparatus according to the second embodiment.
FIG. 21 is a block diagram showing a configuration of an identification expansion unit in FIG. 20;
FIG. 22 is a view for explaining expansion processing according to the first embodiment;
FIG. 23 is a diagram for explaining expansion processing according to the second embodiment;
FIG. 24 is a block diagram illustrating a configuration of a sub-scanning identification expansion unit according to the second embodiment.
FIG. 25 is a flowchart for explaining the operation of the sub-scanning identification expansion unit of the second embodiment.
FIG. 26 is a block diagram showing a configuration of an identification correction apparatus according to the third embodiment.
27 is a block diagram showing the configuration of the image correction apparatus in FIG. 26. FIG.
FIG. 28 is a diagram for explaining the operation of FIG. 27;
29 is a view for explaining the operation of FIG. 27 together with FIG. 28;
30 is a diagram for explaining the operation of FIG. 27 together with FIG. 28 and FIG. 29;
FIG. 31 is a block diagram showing a configuration of an identification correction apparatus according to a fourth embodiment.
32 is a block diagram showing a configuration of a character area determination unit in FIG. 31. FIG.
FIG. 33 is a flowchart for explaining the operation of the fourth embodiment;
FIG. 34 is a view for explaining the operation of the fourth embodiment.
FIG. 35 is a block diagram illustrating a configuration of an identification expansion unit according to a fifth embodiment.
FIG. 36 is a block diagram showing the configuration of the identification correction apparatus according to the sixth embodiment.
FIG. 37 is a block diagram showing a configuration of an identification expansion unit in FIG. 36.
FIG. 38 is a view for explaining an expansion upper limit value in the sixth embodiment.
FIG. 39 is a block diagram showing a configuration of a discrimination correction apparatus according to a seventh embodiment.
40 is a block diagram showing a configuration of an isolated identification expansion unit in FIG. 39. FIG.
41 is a diagram for explaining the image processing of FIG. 39;
FIG. 42 is a sectional view showing the overall configuration of an eighth embodiment.
FIG. 43 is a block diagram showing a configuration of a control circuit according to an eighth embodiment.
FIG. 44 is a block diagram illustrating a configuration of an image processing unit according to an eighth embodiment.
45 is a block diagram showing a configuration of a signal generation device in FIG. 44. FIG.
46 is a block diagram showing the configuration of the identification correction apparatus in FIG. 44. FIG.
[Explanation of symbols]
4 ... Scanner section
40 ... Printer engine
96. Image processing unit
1002 ... Line memory
1003 ... Identification device
1004 ... Identification correction device
1004-1 ... Character area discriminating section
1004-2 ... Identification expansion part
1005 ... Image correction apparatus

Claims (2)

A color scanner unit that reads an original as multi-valued color image data and outputs RGB signals;
RGB / CMY conversion means for converting RGB signals of the color scanner unit into CMY signals;
Signal generation means for taking in CMY signals of the RGB / CMY conversion means and generating density signals, and outputting the density signals and the four CMY signals as color signals;
Identifying means for extracting an edge for each of a plurality of color images based on the color signal output from the signal generating means, and outputting an identification signal representing an edge region and a non-edge region;
Determining means for determining whether the image density of the non-edge region based on the identification signal of the identifying means is a density equal to or higher than a predetermined value corresponding to the character area; In addition to having an expansion means for expanding an area where the image density is determined to be a predetermined value or more into an edge area, and in character mode, processing results of the expansion means for all four signals of the color signal are used as identification correction signals. In the character / photo mode, the processing result of the expansion means for only the density signal of the color signal and the identification signal of the identification means for the CMY signal of the color signal are selected as identification correction signals. Sometimes the identification signal of the identification means for all four signals of the color signal is selected as an identification correction signal An identification correction means having a selection means that,
Image correction means for correcting the color signal based on the identification correction signal of the identification correction means to obtain a C′M′Y′K signal for color printing;
An image processing apparatus comprising: Reading an original as multi-valued color image data and outputting RGB signals;
Converting the RGB signals into CMY signals;
Capturing the CMY signal to generate a density signal, and outputting the density signal and the four CMY signals as color signals;
Extracting an edge for each of a plurality of color images based on the color signal and outputting an identification signal representing an edge region and a non-edge region;
A process is performed to determine whether the image density of the non-edge area based on the identification signal is equal to or higher than a predetermined value corresponding to the character area. A process for expanding an area determined to be an edge area is performed, and in the character mode, the result of the expansion process for all four signals of the color signal is selected as an identification correction signal, and in the character / photo mode. The result of the expansion processing for only the density signal of the color signal and the identification signal for the CMY signal of the color signal are selected as identification correction signals, and the identification for all four signals of the color signal is selected in the photographic mode. Selecting a signal as an identification correction signal;
Correcting the color signal based on the identification correction signal to obtain a C′M′Y′K signal for color printing;
Image processing method, characterized in that it comprises a.

Images