JPH09275509A - Blue print original copying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sharp copy by accurately judging a blue color being a substantial valid image on a blue print original and its background blue color based on three colors, red, green and blue. SOLUTION: A color detection section 43 decides B in the B/black mode and a luminance calculation section 48 calculates a luminance for each pixel based on RGB data. A color decision section 44 discriminates 'B', 'black', 'white' for each pixel based on a luminance threshold level set by a register 41, a luminance calculated by the luminance calculation section 48 and a color decision signal from the color detection section 43. A blue correction processing section 50 sets the luminance as to the pixels whose luminance is lower than the luminance threshold level for blue correction in the blue print original mode to be white data and clears color data corrected by a color slurring correction section 47 and outputs color data and luminance data of the pixels whose luminance is higher than the luminance threshold level for the blue correction to an output selection section 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue-colored original copying apparatus for reading a blue-colored original (blue print) and copying it with a designated color such as blue or red.

[0002]

2. Description of the Related Art Conventionally, a method for identifying blue on a manuscript has been proposed in Japanese Patent Application No. 6-089879 filed by the present applicant. In this method, the original is red,
Blue and black are generated by separating and reading the three colors of green and blue and setting the determination range of blue, black, and white.

[0003]

However, in the above method, it is not possible to distinguish between the peculiar blue spread on the background in the blue-printed original and the blue which is the original effective image, so that a clear copy can be made. There is a problem that it cannot be obtained.

In view of the above problems, the present invention accurately determines blue, which is the original effective image on a blue-printed original, and the background blue, based on the three colors of red, green and blue, and makes a clear copy. It is an object of the present invention to provide a blue-colored original copying apparatus that can obtain the above.

[0005]

In order to achieve the above object, a first means is a blue detecting means for detecting whether or not a pixel is blue based on three colors of red, green and blue which are read from a document. When,
A blue correction unit that compares the brightness of a pixel detected as blue by the blue detection unit in the blue-colored original mode with a threshold value, outputs a pixel whose brightness is brighter than the threshold value as white, and outputs the other pixels as blue as they are. It is characterized by having.

The second means is characterized in that when the mode for detecting a color other than blue and the blue print original mode are set in the first means, the mode is automatically changed to the mode for detecting blue. .

The third means is characterized in that in the first and second means, a mode in which a color other than blue on the blue-colored original is cut and copied, and a copy mode in which it is not cut can be selected. .

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a blue-colored original copying apparatus according to the present invention, FIG. 2 is an explanatory view showing a control system of the copying apparatus shown in FIG. 1, and FIG. 3 shows the video processing section of FIG. 2 in detail. A block diagram, FIG. 4 is a block diagram showing the luminance / color generation unit of FIG. 3 in detail, FIG. 5 is an explanatory view showing a range in which red is determined on the red-green plane, and FIG. 6 is determined to be blue on the blue-red plane. FIG. 7 is an explanatory diagram showing a red determination process, FIG. 8 is an explanatory diagram showing a blue determination process, FIG. 9 is an explanatory diagram showing a black and white determination process, and FIG. 10 is a matrix for color misregistration determination. FIG. 11 is an explanatory diagram showing an extraction pattern, FIG. 11 is an explanatory diagram showing a reference pattern for color misregistration determination, and FIG.
It is a block diagram which shows a color generation part in detail.

1 and 2 show the construction of a copying machine capable of copying with two colors, black and a color other than black. A document reading device 2 is provided above the copying machine body, and an automatic document feeder (ADF) 1 is provided above the document reading device 2. An electrophotographic image forming apparatus 2a having a drum-shaped photosensitive member 3 as a center is provided in the main body of the copying machine.

The original reading device 2 includes a contact glass 4
A document manually set on the document or a document automatically set by the ADF 1 is illuminated by an exposure lamp 5 to be exposed and scanned, and reflected light is reflected by a mirror / lens optical system 6 to a solid-state image sensor such as a CCD line sensor. An image is formed on the light receiving surface of 7. The solid-state imaging device 7 color-separates the original image into R, G, and B by the filters 30R, 30G, and 30B shown in FIG. The R, G, and B electric signals are subjected to necessary image processing as described later, and the image forming apparatus 2a copies the original image onto a sheet.

The photoconductor 3 rotates in the clockwise direction, around which the charger 8 as an image processing unit, a black writing unit 9 for forming a black latent image by a laser beam, and a black color along the rotation direction. Black developing device 10 for developing with toner
And a red writing unit 1 that forms a red latent image by LED light
1, a red developing device 12 for developing with red toner, a transfer paper charger 13, a cleaning device 14 and the like are arranged. Here, the red developing device 12 can be used as a blue developing device by using blue toner instead of red toner. In this case, the red writing section 11 instead forms a blue latent image with LED light.

The transfer paper 17 set in advance in the paper feed tray 15 or the like is fed by the paper feed roller 16, is temporarily stopped by the registration roller 18, and is then conveyed so as to match the toner image on the photoconductor 3. The toner image is transferred by the transfer paper charger 13. Next, the transfer paper 17 is conveyed to the fixing device 20 to fix the toner image, and then discharged.

In FIG. 2, the scanner control unit 21 has a CP
U and a logic circuit, and communicates with a system control unit 22a in an IPU (image processing unit) 22. Particularly, the status from various sensors in the document reading device 2 is detected and the status information is sent to the system. Control unit 22a
Send to The scanner control unit 21 also controls the operation of various driving units in the document reading apparatus 2 to scan the document based on the command information received from the system control unit 22a, and the solid-state image sensor 7 (filter shown in FIG. 3). Thirty
R, 30G, 30B and CCD 31R, 31G, 31
The signal (video data) read by B) is transferred to the IPU
It is transferred to the video processing unit 22b in 22.

The plotter control section 23 is composed of a CPU and a logic circuit, and communicates with the system control section 22a. The plotter control unit 23 particularly detects the states from various sensors in the image forming apparatus and transmits the status information to the system control unit 22a.
Based on the command information received from a and the video data from the video processing unit 22b, the operations of various image processing units and the paper transport unit in the image forming apparatus 2a are controlled to form an image on the transfer paper.

The operation unit 24 includes a CPU, a key switch, and an LC.
It is composed of a D display unit and a logic circuit, and communicates with the system control unit 22a. In particular, the operation unit 24 detects the key input by the operator and transmits the status information to the system control unit 22a.
Various information such as the status of the copying machine is displayed on the LCD display unit based on the command information received from a.

The printer I / F processing unit 25 is composed of a CPU and a logic circuit, and performs command I / F processing between the system control unit 22a and the external host 26. The printer I / F processing unit 25 also exchanges video data with the external host 26, and transfers the video data sent from the external host 26 to the video processing unit 22b. As a result, this copying machine can also function as a printer for the external host 26.

The image memory unit 27 is composed of a CPU, a logic circuit and an image memory, communicates with the system control unit 22a, and in particular, the system control unit 22a receives status information for notifying the state of the image memory unit 27. Along with transmission, various image processing processes such as image data accumulation and image composition based on command information received from the system control unit 22a, and video processing unit 22b of processed data
Transfer processing to.

Next, referring to FIG. 3, the video processing section 22b.
Will be described in detail. The image information of the original is R, G, B
Each color separation filter 30R, 30G, 30B and CCD3
The signals are converted into R, G, and B electric signals by 1R, 31G, and 31B and applied to the video processing unit 22b. In the video processing unit 22b, first, these signals are A / D respectively.
After being converted into digital data by the converters 32R, 32G, and 32B and then corrected by the shading correction circuit 33, the data is temporarily stored in the buffer memory 34, and the three lines of CCD 31 are stored in the buffer memory 34.
The synchronization deviation of the R, G, B data due to the reading of R, 31G, 31B is corrected.

As shown in FIGS. 4 and 12, the luminance / color generation circuit 35 uses the R, G, and B digital data from the buffer memory 34 to generate a luminance signal of 8 bits per pixel and its attention. A color determination signal indicating whether the pixel is red (in the red / black mode) or blue (in the blue / black mode) is generated, and is output to the scaling processing circuit 36 together with the synchronization signal. The scaling processing circuit 36 performs enlargement / reduction processing in the main scanning direction on the luminance signal and the red determination signal. Here, while performing interpolation processing using a line memory, scaling processing in the main scanning direction is performed by performing thinning processing (when reducing) and reading twice (when enlarging), and scaling processing in the sub-scanning direction is performed. The scanning speed of the document reading device 2 is changed.

The path control circuit 37 at the next stage outputs the brightness signal and the color determination signal sent from the scaling processing circuit 36 based on the parameters set by the system control unit 22a to the image memory unit 27 and the image processing circuit 38. The luminance signal and the color determination signal sent from the image memory unit 27 to the image processing circuit 38, and the luminance signal sent from both the scaling processing circuit 36 and the image memory unit 27. The color determination signals are combined and transmitted to the image processing circuit 38.

The image processing circuit 38 performs γ correction on the luminance signal and the color determination signal sent from the bus control circuit 37.
Image processing such as MTF correction, color separation, smoothing, dither processing, and error diffusion is performed, and the result is transmitted to the path control circuit 39 together with the synchronization signal. The print control circuit 40 has a ROM in which various image patterns are coded and stored, and the system control unit 2
The image pattern information is transmitted to the path control circuit 39 based on the parameters set from 2a.

The path control circuit 39 is a system controller 22a.
The image processing circuit 3 based on the parameters set from
8 and the printer I / F processing unit 25 to combine the image data sent from each other, and the image processing circuit 38 and the printer I / F.
Each image data sent from the processing unit 25 and the composite image data are selected, and the image pattern from the print control circuit 40 is combined with the selected image data.

The path control unit 39 also outputs the black image data together with the synchronizing signal to the black writing unit 9, and outputs the red and blue image data together with the synchronizing signal to the red writing unit 11 via the buffer memory 41. The buffer memory 41 delays and outputs the blue red image data by the arrangement interval of the black writing unit 9 and the red writing unit 11. Here, as described above, when the red developing device 12 is set, a red latent image is formed by the red writing unit 11 so that copying can be performed in two colors of black and red (red / black mode). In addition, when a blue developing device is set instead of the red developing device 12, a red latent image is formed by the red writing unit 11 to copy in two colors of black and blue (blue / black mode). You can

Next, referring to FIG. 4, the luminance / color generation circuit 3
5 will be described in detail. The color detection unit 51 is R (red),
Based on each of the G (green) and B (blue) data, "color (R in R / black mode, B in B / black mode)" and "non-color data" are detected, and the black / white determination unit 52 is detected. Determines black and white based on the "data that is not a color" detected by the color detection unit 51. The color misregistration correction unit 53 is the color detection unit 5.
“Color data” detected by 1 and the black and white determination unit 5
The color misregistration is corrected based on the "monochrome data" determined in 2 and "luminance image data" and "color image data" are output.

1. Color Detection Unit 51 First, color detection is performed based on the R, G, B light data for each pixel when the designated color is R (R / black mode) based on the R, G, B data. , When the designated color is B (B /
In the case of the black mode), it is performed based on the light amounts of B and R for each pixel. In detail, in the R / black mode, first,
The color that is seen as R is detected from the color image. To determine the detection range of R, two correction values K _R1 and K _R2 for R are set.
(K _R2 <K _R1 ) and the threshold value K _G for _G are set in advance.

[0026] Then, R, G, R from the amount of B, taking out the light amount of G, based on the _{G> K G ... (1)} R> G + K R1 ... (2) R> G + K R2 ... (3) FIG. 5, as shown in FIG. 7, equations (1) and (2)
Is satisfied, or the pixel for which the formula (1) is not satisfied and the formula (3) is satisfied is identified as red, and the other pixels are determined not to be red.

Further, in the B / black mode, first, in order to detect the color seen as B from the color image and determine the detection range of B, three correction values K _B1 and K _B2 (K _B2 < _{B B} <
K _B1 ) and a threshold value K _R for _R are preset.

Then, the light quantities of R and G are extracted from the respective light quantities of R, G, and B, and R> K _R (4) B> R + K _B1 (5) B> R + K _B2 (6) 6, equations (4) and (5) as shown in FIG.
Is satisfied, or the pixel for which the formula (4) is not satisfied and the formula (6) is satisfied is identified as blue, and the other pixels are determined not to be blue.

2. Black-and-white determination unit 52 In the black-and-white determination, with respect to the pixel determined to be not R in the R / black mode and the pixel determined not to be B in the B / black mode in the above “1. Color detection”,
As shown in FIG. 9, the brightness (2R + 5G + B) / 8 is compared with the threshold value K _th for black-and-white judgment to judge whether it is white or black.

3. Color misregistration correction unit 53 Here, the process of converting a color image into two colors of R / black or B / black can be performed by the above "1. color detection" and "2. black and white determination". Due to the uneven illumination of the reading optical system, the position shift of the CCD line, and the like, color shift may occur in the two-color image converted by the above "1. Color detection" and "2. Black and white judgment". In particular, color shift is likely to occur at the edge portion of the image. Therefore,
In this "3. Color misregistration correction", the pixels around the target pixel are checked to determine the color misregistration of the pixel, and the correction is performed.

As a method of correction, as shown in FIG. 10 (a), with the pixel of interest as the central pixel, two pixels on each of the left and right of the same line and pixels at the same position on the front and rear two lines, that is, a matrix of 5 × 5 pixels. 10B, a total of eight linear patterns LP1 to LP8, each consisting of four pixels with the pixel of interest “33” being the third as shown in FIG. To extract. Then, the extraction patterns LP1 to LP8 are compared with seven preset combinations of “color”, “color”, “black”, and “white” as shown in FIG. If there is a color shift, it is determined that a color shift has occurred, and the pixel of interest is corrected as shown in FIG.

Next, a specific configuration of the brightness / color generation circuit 35 of the present invention will be described with reference to FIG. Register 41
In order to detect the color of R or B, to judge the color, and to judge the color of black and white ・ Luminance threshold for blue correction ・ Mode (R / black mode or B / black mode, normal two-color mode or blue-baked original Mode, whether or not to cut other than blue in blue print original mode) -luminance threshold Kth for color separation-first correction value K _R1 (in R / black mode) or K _B1 (B /
Black mode) ・ Second correction value K _R2 (R / black mode) or K _B2 (B /
Black mode) ・ Color threshold K _G (R / black mode) or K _R (B / black mode) is set.

When the blue-colored original mode is set, when the R / black mode is set, the mode is automatically changed to the B / black mode, and the input selection section 42, the color detection section 43, the color The determination unit 44 and the blue correction processing unit 50 are set. As a result, the blue color of the blue-colored original is detected and developed by the red developing device 12 with red toner. When the B / black mode is set, the blue color of the blue-colored original is detected and the blue developing device 12 develops it with blue toner.

The input selection section 42 selects two color signals (8 bits) from RGB according to the mode set in the register 41 and outputs them to the color detection section 43. Specifically R
/ R and G are selected in the black mode, and B and R are selected in the B / black mode. The color detection unit 43 determines R based on the equations (1) to (3) in the R / black mode, determines B based on the equations (4) to (6) in the B / black mode, and outputs a determination signal. Output to the color determination unit 44.

The brightness calculator 48 uses RGB data and FIG.
The brightness of each pixel (2R + 5G
+ B) / 8 is calculated and output to the color determination unit 44. The color determination unit 44 determines “color”, “black”, and “white” based on the luminance threshold value Kth set in the register 41, the luminance calculated by the luminance calculation unit 48, and the color determination signal from the color detection unit 43. The determination is made for each pixel, and the determination result is output to the matrix generation unit 45.

The matrix generation unit 45 accumulates the determination results of the color determination unit 44 for 5 lines, extracts 5 pixels from each line, and sets the pixel of interest as the third pixel in the matrix of 5 × 5 pixels shown in FIG. 2 horizontal, 2 vertical, 4 diagonal,
A total of eight linear patterns LP1 to LP8 are extracted and output to the pattern matching unit 46. The pattern matching unit 66 uses the linear patterns LP1 to LP8 as shown in FIG.
The comparison result is output to the color misregistration correction unit 47.

The color misregistration correction unit 47 corrects the pixel of interest when the comparison result is "match" and outputs it to the blue correction processing unit 50 without correcting the pixel of interest when the comparison result is "mismatch".
Further, the timing adjustment unit 49 delays the brightness calculated by the brightness calculation unit 48 and outputs it to the blue correction processing unit 50 in order to keep timing with the two-color data corrected by the color misregistration correction unit 47.

The blue correction processing section 50 is for binarizing the image data in order to copy the blue-printed document more clearly and outputting the bright portion, that is, the background of the blue-printed document in white. That is, R / set in the register 41
The brightness calculated by the brightness calculation unit 48 is binarized based on the black mode or the B / black mode and the brightness threshold for blue correction, and in this case, for a pixel whose brightness is lower than the brightness threshold for blue correction, The brightness value is set to white data, the color data corrected by the color misregistration correction unit 47 is also turned off, and the color data and the brightness data of the pixel whose brightness is higher than the brightness threshold for blue correction are output to the output selection unit 51. .

The output selection unit 51 determines whether to cut the color data and the luminance data from the blue correction processing unit 50 in the normal two-color mode or the blue-colored original mode, and in the blue-colored original mode, except for blue. The blue-colored original is processed according to the mode. That is, in the normal two-color mode, the color data and the luminance data from the blue correction processing unit 50 are output through. On the other hand, in the blue-colored original mode in which a color other than blue is cut, the blue correction processing unit 50
The luminance data for which the color data from is turned off is output as white data, and is output as it is in the non-cutting mode.

[0040]

As described above, according to the first aspect of the present invention, the luminance of the pixel detected as blue is compared with the threshold value, and the pixel whose luminance is brighter than the threshold value is output as white. A clear copy can be obtained by accurately determining the originally valid image of blue on the blue-printed original and the background blue.

According to the second aspect of the invention, when the mode for detecting a color other than blue and the blue-colored original mode are set, the mode for automatically detecting blue is automatically changed. It is possible to obtain a clear copy in a color other than blue by accurately judging the original effective image of blue and the background blue.

According to the third aspect of the present invention, it is possible to select a mode in which a color other than blue on the blue-colored original is cut and copied, and a mode in which the color is not cut are selected. You can cut black like writing and copy it, or copy without cutting.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a blue-colored original copying apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a control system of the copying machine shown in FIG.

FIG. 3 is a block diagram showing the video processing unit of FIG. 2 in detail.

FIG. 4 is a block diagram showing in detail the luminance / color generation circuit of FIG.

FIG. 5 is an explanatory diagram showing a range determined to be red on a red-green plane.

FIG. 6 is an explanatory diagram showing a range determined to be blue on a blue-red plane.

FIG. 7 is an explanatory diagram showing red determination processing.

FIG. 8 is an explanatory diagram showing blue determination processing.

FIG. 9 is an explanatory diagram showing a monochrome determination process.

FIG. 10 is an explanatory diagram showing a matrix for color misregistration determination and an extraction pattern.

FIG. 11 is an explanatory diagram showing a reference pattern for color misregistration determination.

12 is a block diagram showing in detail the luminance / color generation circuit of FIG.

[Explanation of symbols]

 41 register 43 color detection unit 43 color determination unit 48 brightness calculation unit 50 blue correction processing unit 51 output selection unit

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03G 15/01 117 H04N 1/46 Z (72) Inventor Tomonori Tanaka 1-3-6 Nakamagome, Ota-ku, Tokyo No. In Ricoh Co., Ltd. (72) Inventor Toshimi Yamamura 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A blue detecting means for detecting whether or not the pixel is blue based on three colors of red, green and blue obtained by reading the original, and blue detected by the blue detecting means in the blue-ray original mode. A blue-colored original copying apparatus comprising: a blue correction unit that compares the brightness of a pixel with a threshold value, outputs a pixel whose brightness is higher than the threshold value as white, and outputs other pixels as blue as they are. 2. The blue-printed original copy according to claim 1, wherein when a mode for detecting a color other than blue and a blue-printed original mode are set, the mode is automatically changed to a mode for detecting blue. apparatus. 3. The blue-printed document copying apparatus according to claim 1, wherein a mode in which a color other than blue on the blue-printed document is cut and copied, and a mode in which the copy is not cut can be selected. .