JP3077241B2 - Image processing device - 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 apparatus which performs processing suitable for black characters, color characters, and pictures.

[0002]

2. Description of the Related Art As an image processing apparatus, for example, in a digital color copying machine, image reading means for scanning and reading an original, image data processing means for processing / editing the read image data, and recording for recording the processed / edited image data Means, and control means for controlling image reading, processing / editing, and recording. The image data processing means can perform various editing processes on the image data. FIG. 7 shows an example of the overall apparatus configuration of a color copying machine having a film image reading device. FIG. 8 shows the configuration of the image data processing system of the color copying machine. In the color copier, a base machine 30 includes a platen glass 31, an image input terminal (IIT) 32, an electric system control storage unit 33, an image output terminal (IOT) 34, a paper tray 35,
It comprises a user interface (U / I) 36, and optionally includes an edit pad 61, an automatic document feeder (ADF) 62, a sorter 63, a film projector (F / P) 64, and a mirror unit (M).
/ U) 65 is provided.

[0003] The image input terminal 32 includes an imaging unit 37, wires 38 for driving the imaging unit 37,
The imaging unit 37 includes a driving pulley 39 and the like.
The three primary colors of light B (blue), G (green),
The image information of a color document read out using a CCD line sensor after being separated into R (red) colors is converted into a multi-gradation digital image signal BGR and output to an image processing system. The image processing system is housed in the electrical system control housing unit 33 and receives various BGR image signals to perform various conversions, corrections, and edits to improve color, gradation, definition, other image quality, and reproducibility. And the like, and converts the primary colors Y (yellow), M (magenta), C (cyan), and K (black) of the toner, and turns on / off the tone toner signal of the process color. It is converted into a valued toner signal and output to the image output terminal 34. The image output terminal 34 includes a scanner 40,
It has a photosensitive material belt 41, and converts an image signal into an optical signal at a laser output section 40a, and outputs a polygon mirror 40b, F / F
A latent image corresponding to the original image is formed on the photosensitive material belt 41 via the θ lens 40c and the reflection mirror 40d, and the image is transferred to a sheet conveyed from the sheet tray 35 to discharge a color copy.

In the image output terminal 34, a photosensitive material belt 41 is driven by a driving pulley 41a, and a cleaner 41b, a charging device 41c, each developing device 41d of YMCK, and a transfer device 41e are arranged around the photosensitive material belt 41.
e, a transfer device 42 is provided. And
The paper sent from the paper tray 35 via the paper transport path 35a is added, and in the case of four-color full-color copying, the transfer device 42 is rotated four times to transfer each of the YMCK latent images onto the paper. Is fixed from a transfer device 42 via a vacuum transfer device 43 by a fixing device 45 and discharged. SSI
(Single sheet inserter) 35b is the paper transport path 3
5a, the paper can be selectively supplied manually. The user interface 36 is for the user to select a desired function and instruct the execution conditions thereof. The user interface 36 includes a color display 51 and a hard control panel 52, and further includes a combination of an infrared touch board 53 and direct instructions with soft buttons on the screen. I can do it. The electric system control storage unit 33 is provided with the image input terminal 3 described above.
2. a plurality of control boards configured for each processing unit such as an image output terminal 34, a user interface 36, an image processing system (IPS), a film projector 64, and the like;
4. An MCB board (machine control board) for controlling the operation of mechanisms such as the automatic document feeder 62 and the sorter 63, and a SYS board for controlling the whole of the board.

Next, the image data processing will be described. In FIG. 8, an IIT (image input terminal) 100
Are three primary colors of light B, G,
R is read into a color original and converted into digital image data. An IOT (image output terminal) 115 performs exposure and development with a laser beam to reproduce a color image. IIT10
The END conversion circuit 101 to the IOT interface 110 between the 0 and the IOT 115 constitute an image data edit processing system (IPS; image processing system). The B, G, and R image data is converted to Y toner. , M,
C, and further convert to K (black or black), and output a toner signal corresponding to the developed color in each development cycle. IIT
Then, for each of B, G, and R using a CCD sensor, one pixel is read at a size of, for example, 16 dots / mm, and the data is 24 bits (3 colors × 8 bits;
(256 gradations). The CCD sensor has B, G, and R filters mounted on the upper surface, has a density of 16 dots / mm, has a length of 300 mm, and has a length of 190.5 m.
Since scanning is performed at 16 lines / mm at a process speed of m / sec, read data is output at a speed of 15 M pixels per second for each color. And II
In T, the analog data of the B, G, and R pixels are log-converted, thereby converting the reflectance information into density information and further converting into digital data.

The image processing system (IPS) is based on EN
D conversion (Equivalent Neutral Density) module 101, color masking module 102, document size detection module 103, color conversion module 104, UCR (Under Color Remova)
l: Under color removal & black generation module 105, spatial filter 106, TRC (Tone Reproduction Control;
It comprises a color tone correction control) module 107, a scaling processing module 108, and a screen generator 109, and receives B, G, and R color separation signals from the IIT 100, and reproduces color, gradation, and definition. In order to enhance the reproducibility of the image, various data processing is performed, and the toner signal of the development process color is converted into an on / off binarized toner signal and output to the IOT 115. The END conversion module 101 adjusts (converts) to a gray-balanced color signal. Color masking module 102
Converts the B, G, and R signals into signals corresponding to the Y, M, and C toner amounts by performing a matrix operation. The document size detection module 103 performs document size detection during prescanning and platen color erasing (frame erasing) processing during document scanning. The color conversion module 104 converts a color specified in a specific area according to an area signal input from the area image control module.

The UCR & black generation module 105 generates an appropriate amount of K so as not to cause color turbidity, reduces Y, M, and C by an equal amount according to the amount, and sets a mono color mode,
K signal and Y, according to each signal of full color mode
The signals after the undercolor removal of M and C are gated. The spatial filter 106 is a non-linear digital filter having a function of recovering blur and a function of removing moiré. TR
The C module 107 performs density adjustment, contrast adjustment, negative / positive inversion, color balance adjustment, and the like for improving reproducibility. Reduction processing module 108
Performs the enlargement / reduction processing in the main scanning direction, and performs the enlargement / reduction processing in the sub-scanning direction by adjusting the scan speed of the document. The screen generator 109 converts the process color gradation toner signal into an on / off binarized toner signal and outputs the binarized toner signal. The binarized toner signal is output to the IOT 115 through the IOT interface module 110.

The area image control module 111 has an area generating circuit and a switch matrix, and has a configuration in which seven rectangular areas and their priorities can be set in the area generating circuit. The control information of the area is set. The control information includes color conversion, color mode such as mono color or full color, modulation select information such as photographs and characters, TRC select information, screen generator select information, and the like. The color masking module 102, the color conversion module 104 , UCR module 105, spatial filter 106, and TRC module 107. The switch matrix can be set by software. The edit control module includes the plane memory 112 and the color palette video switch circuit 1.
13 and a font buffer 114 for performing various editing controls. That is, the edit control module reads a manuscript such as a pie chart instead of a rectangle, and enables a coloring process in which a designated area having an unlimited shape is painted with a designated color.
The editing command for each point of the original is written in the plane memory 112 and is set with four bits by the four plane memories.

In the IPS, the color separation signal (B,
(G, R signals) into toner signals (Y, M, C, K signals), how to adjust the color balance, how to adjust the color in accordance with the IIT reading characteristics and the IOT output characteristics. The problem is how to reproduce, how to adjust the balance of density and contrast, and how to adjust edge emphasis, blur, and moire. Therefore, in IPS, B, G, and
With respect to the R color separation signal, 8-bit data (256 gradations) is input to the END conversion module 101, and the END conversion module 101 first performs END conversion and then converts (color masking) into Y, M, and C toner signals. Then, processing with full-color data is more efficient than original document size, frame erasing, color conversion processing, then undercolor removal and black generation,
The toner signal X of the development color is selected. However, processing such as spatial filter, color modulation, TRC, scaling, etc.
By processing the developed color data, the amount of processing is reduced compared to the case of processing with full color data, the number of conversion tables used is reduced to 1/3, and the number of types is increased and the adjustment flexibility is increased. , Color reproducibility, gradation reproducibility,
The reproducibility of the definition is improved. Full color (4 colors)
In the case of, after the original size detection, the editing area detection, and other original information are detected in the prescan, for example, first, a copy cycle in which the toner signal Z of the developed color is set to Y, and then the toner of the developed color Each time a copy cycle in which the signal Z is set to M is executed sequentially, signal processing corresponding to four document reading scans is performed. A digital color copying machine having an editing function is disclosed in, for example, Japanese Patent Application No. 1-47088.

[0010]

The UCR & black generation module 105 generates a K toner signal from the Y, M, and C toner signals converted from the B, G, and R image signals. Image generation processes such as density adjustment, contrast adjustment, negative / positive inversion, and color balance are performed. That is, image signals of black characters, color characters, and pictures are performed by one process. But,
Black characters, color characters (hereinafter referred to as "character image signals") and pictures (hereinafter referred to as "halftone image signals") have suitable processes, respectively. However, in the conventional method, character image signals and halftone image signals are used. Are generated without any distinction, and the image signal input in Y, M, and C is subjected to black generation and undercolor removal, and is output. Therefore, there is a problem that reproducibility is reduced. The purpose of the present invention is
An object of the present invention is to provide an image processing apparatus in which reproducibility is improved by performing processing suitable for each of image signals of pictures and characters.

[0011]

In order to achieve the above-mentioned object, an image processing apparatus according to the present invention comprises: M. An undercolor removing unit that outputs a halftone image signal and a character image signal that have been subjected to undercolor removal and black formation for each development cycle for the C image signal, and stores the halftone image signal output from the undercolor removal unit. A first storage means, a second storage means for storing a character image signal output by undercolor removal, M. A T / I separation unit for determining whether the C image signal is a halftone image or a character image for each development cycle, and outputting the result;
The halftone image signal stored in the first storage means and the second
And a means for switching and outputting the character image signal stored in the storage means, and a means for performing an image generation process based on the image signal selected by the selection means.

[0012]

The first and second storage means are provided after the undercolor removal means.
The halftone image signal and the character image signal
The delay due to the area determination is absorbed. In the under color removing means, for example, the minimum value is extracted from the Y, M, and C image signals, and the signal is set to K, and the Y, M, C, and K are converted into halftone image signals corresponding to the values for each development cycle. And character image signals, and the respective image signals are stored in the first storage means and the second storage means. The T / I separation unit determines whether the image is a halftone image or a character image for each development cycle, and outputs the result. Based on the result, the selection means selects a halftone image signal and a character image signal, and performs image generation processing on the image signal.

[0013]

An embodiment of the present invention will be described with reference to the drawings. The present invention is characterized by the undercolor removal function of the IPS. First, the configuration of the IPS and the function of each unit will be described. FIG. 1 shows blocks of the overall configuration of the IPS. FIG. 2 shows constituent blocks of the image editing processing unit. Image input unit 10
0 is, for example, R, G, B arranged at right angles to the sub-scanning direction.
It has a reduction type sensor composed of three line sensors, and scans in synchronization with a timing signal from the timing generation circuit 12 to read an image. In addition to the above, the timing generation circuit 12 performs image data processing when performing processing that causes a large delay, such as gray balance processing in the ENL 15 described below of image data and separation processing of picture data and character data in the picture character separation circuit 20. Prior to this, the processing may be started in advance, and timing with image data processing may be taken. The read image data is subjected to shading correction for the balance between pixels due to various factors by the shading correction circuit 11, and then the gap correction circuit 13 performs gap correction between the line sensors. This gap correction is for delaying the image data read by the FIFO 14 by an amount corresponding to the gap so that R, G, and B image signals at the same position can be obtained at the same time.

ENL (Equivalnt Neutral Lightness)
Numeral 15 is for performing gray balance, and inverts the negative / positive inversion by taking the gray for each pixel in accordance with a negative / positive inversion signal from the editing processing unit 400 described later. Can be reversed. The matrix circuit 16a converts the R, G, B image signals gray-balanced into L ', a', b 'image signals according to a control signal from the editing processing unit 400 described later. This conversion from R, G, B to L ', a', b 'is for facilitating the interface with the outside such as a computer.

The selector 17 is controlled by a signal from the edit processing unit 400 to output the output of the matrix circuit 16a,
Alternatively, it is for selectively extracting image data from the memory system 200 which is an interface with an external computer. The background removing circuit 18 detects the background density by creating a histogram of the density of the document by, for example, pre-scanning, and skips pixels having a density lower than the background density to improve the copy quality of a fogged document such as a newspaper. Things. The document detection circuit 19 detects and stores a document size by detecting a boundary between the back surface of the black platen and the document and obtaining an external rectangle. The matrix circuit 16b converts the L ′, a ′, and b ′ image signals color-edited by the edit processing unit 400 into Y, M, C
To the toner color.

A pictographic (T / I) separating circuit 20 divides the color-edited image data into a plurality of pixels,
It identifies the area of black characters / patterns (characters / halftones). In the under color removing circuit 21, the generation of the black board and the mono color /
Equal amounts of Y, M, and C are removed according to the full-color mode signal and black to output process color image data.
Further, hue determination is performed to generate a hue signal (Hue signal). The under color removal circuit 21 generates black from the Y, M, and C converted by the matrix circuit 16b, and removes the same amount of Y, M, and C according to the monochrome / full-color mode signal and black to remove the pattern. A halftone image signal and a character image signal for black characters and color characters are generated. The halftone image signal is stored in the FIFO 22a, and the character image signal is stored in the FIFO 22a.
b.

The selector 30 converts the halftone image signal and the character image signal from the T / I separation circuit 20 into the area decoder 2.
4 and is output to the data reset circuit 31 by a control signal based on the wide area T / I separation result. The data reset circuit 31 leaves the image signal corresponding to the current development cycle and resets the others to "0" by a control signal based on the wide area T / I separation result output from the T / I separation circuit 20 to the area decoder 24. Processing is performed to prevent the character image from becoming cloudy. The TRC 27 is for adjusting the density in accordance with the characteristics of the IOT, and this image data is stored in a memory system or output as an image by a screen generation unit (ROS) 300.

The enlargement / reduction circuit 23a is for enlarging / reducing the execution area of the area control information for an image even when the area is reduced / enlarged. is decoded is subjected to each part of the processing areas Deco over da 24. Also, the area Deco chromatography da 24 edit command or area identification, and generates a switching signal for each of the parameters from the hue. The image data reduced or enlarged by the enlargement / reduction circuit 23b is subjected to moire removal and edge enhancement by the filter 25, and the multiplier 26 and the TRC 27 appropriately select a coefficient and a conversion table for each color component. Is adjusted for color and density. The multiplier 26 performs an operation of ax + b on the image data x to which the coefficients a and b are given, and
7 is to be corrected. The TRC 27 is for adjusting the density according to the characteristics of the IOT 34.

The PAL 29 is a decoder for switching the conversion table of the TRC 27 according to the development process and the area identification. The image data prepared in this way is stored in a memory system or is developed into dots by the screen generation unit 28 of the ROS 300, and is output as a halftone image. Next, the editing processing unit will be described with reference to FIG. The edit processing unit 400 is for performing color conversion, color editing, area generation, and the like. The image signals L ′, a ′, and b ′ from the selector 17 are used to detect the detection color of the marker color and the color by the LUT 415a. Chromaticity (hue, saturation) information is converted from a and b in the rectangular coordinate system to C and H in the polar coordinate system so that editing, color conversion, and the like can be easily performed. The color conversion & palette 413 has, for example, 32 types of palettes for colors used in color conversion and color editing. Markers are applied to the image data L, C, and H in accordance with an editing command input through the delay circuit 411a. It performs processing such as color detection, color editing, and color conversion. Only the image data of the area where the processing such as the color conversion is performed is input to the color conversion & palette 413, output from the selector 416 through the LUT 415b, and the image data of the other areas is output directly from the selector 416. Then, the signal is sent to the aforementioned matrix circuit 16b.

The density conversion / area generation circuit 405 receives the marker colors (three colors) from the color conversion & palette 413 and the 4-bit signal of the closed area. The density conversion / region generation circuit 405 performs a binarization process of “1” when the number of black pixels among the 16 pixels is equal to or more than a predetermined number in a 4 × 4 window using FIFOs 410a, 410b, and 410c. 40
A density conversion from 0 spi to 100 spi is performed. The marker signal (closed loop and marker dot) generated in this way is written into the plane memory 403 by the density conversion / area generation circuit 405, and the marker / dot signal is not erroneously detected as a small dust as a marker. A coordinate value generating circuit 407 detects a marker / dot by delaying three lines by the FIFO 408 to make a 3 × 3 window, generates a marker / dot coordinate value, and stores it in the RAM 406. Note that the marker dot is also stored in the plane memory 403, but this processing is performed to prevent erroneous detection.

The plane memory 403 is a memory for storing editing commands for performing color conversion, color editing, and other area editing. For example, the area is designated by an editor pad (not shown), and the area is designated. Edit command can be written to That is, the editing command for the area specified by the editor pad is transferred to the graphic controller 401 through the CPU bus, and written into the plane memory 403 from the graphic controller 401 via the DRAM controller 402. The plane memory 403 is composed of four planes.
The reading of the area from 03 is performed simultaneously on four surfaces, and 0 to 15
Up to 16 types of editing commands can be controlled.

The 4-bit editing command stored in the plane memory 403 is read out in synchronization with the output of the image data, and is used for editing processing in the color conversion & palette 413 and switching of parameters in the image data processing system. In this case, density conversion from 100 spi to 400 spi is necessary, and the processing is performed by the density conversion / area generation circuit 405. The density conversion / area generation circuit 405
O409a and 409b perform 3 × 3 block formation and perform data complementation from the pattern, thereby performing density conversion from 100 spi to 400 spi so that boundaries such as closed loop curves and conversion regions do not become jagged. Delay circuits 411a, 411b, 1M FIFO4
Reference numeral 12 and the like are for adjusting the timing between the edit command and the image data.

Hereinafter, the undercolor removal processing will be described.
FIG. 3 shows a block of the first embodiment for generating a character image signal of the under color removal circuit. In this embodiment, the image signal (toner signal) of the developed color is output as it is as a character image signal without UCR processing in each development cycle. The minimum value processing circuit 21a extracts the minimum value of Y, M, and C output from the matrix circuit 16b, and outputs the signal to K
Output as The selector 21b has Y, M, C and K
Is selected for each development cycle, and a character image signal corresponding to the value is read out from the look-up table LUT 21c and output to the FIFO 22b. FIG. 4 shows a block of a second embodiment for generating a character image signal of the under color removal circuit.
In the present embodiment, Y output from the matrix circuit 16b,
A luminance signal is generated based on M and C and output as a character image signal L ′. The generation circuit 21d multiplies each signal by coefficients α, β, and γ based on Y, M, and C to obtain a sum L ′ of the signals, reads a character image signal corresponding to this value from the LUT 21c, and outputs the signal to the FIFO 22b. I do. Note that L ′ = α
Y + βM + γC (α + β + γ = 1).

According to the above-described embodiment, processing suitable for a character image signal can be performed separately from a halftone image signal, so that character reproducibility is improved. The halftone image signal and the character image signal are selected for each development cycle, and this control signal is created by blocking such as wide area T / I (pictogram) separation. In this blocking, a delay in the sub-scanning direction occurs due to wide-area T / I separation. That is, in the wide-area T / I separation, since a pattern or a character is determined for each predetermined number of pixels, the input image data is, for example, 4 lines ×
A delay occurs when eight pixels are blocked. The delay absorption by this block processing will be described with reference to FIG. In the figure, Y, M, and C output from a matrix circuit 16b are black-generated and under-color-removed by an under-color removal circuit 21, and each of the FIs is output as a halftone image signal and a character image signal.
The signals are output to the FOs 22a and 22b. Image signal is FIFO
And is input to the selector 30. The selector 30 converts the halftone image signal and the character image signal from the T / I separation circuit 20 to the wide area T /
It is selected by a control signal based on the I separation result and output to the data reset circuit 31.

According to this embodiment, the T / I separation result can be effectively used for switching between the halftone and character image signals, and the two systems immediately after the UCR process, that is, each of the character and halftone image signals The FIFO of B, G, R, Y, M, C, etc. before UCR processing is inserted into the output of
FIFO can be reduced compared to the system. The character image signal includes a black character and a color character, and a data reset circuit 31 shown in FIG. 6 is provided after the selector circuit 30 in order to prevent each character from being clouded. The data reset circuit 31 leaves data corresponding to the current development cycle by a control signal based on the wide area T / I separation result,
Reset processing for setting others to "0" is performed. By the way, black color reproduction of black characters, in order to suppress the turbidity due to black mingled in the color character, the hue signal required at the time of edge enhancement (Hue signal), but I was trying to achieve by suppressing the edge emphasis of the unwanted color In addition, it is difficult to completely determine a necessary color, or it is difficult to suppress color turbidity by determining only an edge, and it has not been possible to realize a single-color reproduction of black characters.

According to this embodiment, the hue signal reset on black character judgment, the black signal reset when a color character judgment, solid black reproduction in black characters, turbidity due to black mingled in the color character can be prevented. As another method for preventing turbidity of a black character or a color character, a reset can be performed by the TRC 27 immediately before output. According to this method, the processing is performed immediately before output, rather than resetting inside the image processing and continuing processing on an image different from the actual document, so that more natural processing is possible.

[0052]

As described above, according to the present invention, a character image signal is generated separately from a halftone image signal, and these image signals are selectively output based on pictorial character separation results. Processing suitable for the image signal
Reproducibility of pictures and characters is improved. In addition, the first and second
Means for storing the halftone image signal after the undercolor removing means.
Signal and character image signal
Can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of an image processing system (IPS) of an image processing apparatus according to the present invention.

FIG. 2 is a block diagram of an image editing unit of the image processing system.

FIG. 3 is a block diagram illustrating a circuit configuration for generating a character image signal.

FIG. 4 is a block diagram illustrating another circuit configuration for generating a character image signal.

FIG. 5 is a block diagram showing a circuit configuration for absorbing a delay of an image signal.

FIG. 6 is a block diagram showing a circuit configuration to which a data reset circuit for preventing turbidity of black characters and color characters is added.

FIG. 7 is a configuration diagram of a digital color copying machine.

FIG. 8 is a diagram illustrating an example of a configuration block of a conventional image processing system.

[Explanation of symbols]

 Reference Signs List 20 pictogram separation circuit 21 under color removal circuit 30 selector circuit 31 data reset circuit 100 image input unit 200 memory system 300 screen generation unit 400 image editing processing unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-263974 (JP, A) JP-A-3-44271 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/00 H04N 1/40-1/409

Claims (1)

(57) [Claims] 1. Y. M. For C image signalDevelopment cycle
EveryUnder color removal and ink creationWasFor halftone image signals and text
Image signalWhenUnder color removing means for outputtingThe halftone image signal output from the under color removing means is
First storage means for storing; The character image signal output from the under color removal is stored.
Second storage means for performing Said Y. M. Halftone for every development cycle for C image signal
Determine whether it is an image or text image and output the result
T / I separation means; Based on the result output by the T / I separation means,
The halftone stored in the first storage means for each image cycle
Image signal and character image stored in the second storage means
Switch to the signal Selecting means for outputting,An image based on the image signal selected by the selection means;
Means for performing generation processing; Characterized by having Image processing device.