JPH0278374A - Color picture reader - Google Patents

Abstract

PURPOSE:To reproduce a white/black area of a color picture read digitally with higher definition. CONSTITUTION:A picture signal outputted from a sensor 1 is inputted to an A/D converter 2 and R, G, B signals are converted respectively into digital R, G, B signals. While the sensor 1 scans the color area, the picture data is inputted to a density conversion color masking circuit 4 as it is as a R, G, b parallel data. On the other hand, while the sensor 1 scans the black/white area, the R, G, B parallel data is converted serially in the order of G B R by a white/black area signal and the converted data is inputted to a gradation correction circuit 6 as a Bk(black) signal. A C(cyan), a Y(yellow) signal and an M(magenta) signal outputted from a density conversion color masking circuit 4 are subject to background color elimination processing by a background color elimination circuit 5 and the resulting signal is outputted to the gradation correction circuit 6. The C, M, Y and Bk signals outputted from the background color elimination circuit 5 is subject to gradation correction by the gradation correction circuit 6 and printed out by a printer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image reading device that obtains a color copy image based on a digitally read color image. The present invention relates to a color image reading device that reproduces high-definition images.

[Prior Art] In recent years, digital color copying machines have been developed that digitally separate and read original documents, perform desired processing on the read digital image signals, and perform color recording based on the obtained digital color image signals. It has become popular.

As shown in FIG. 7, the image reading device in this type of apparatus is comprised of a color sensor 71 in the form of a CCD (charge coupled device) and an A/D converter 72. 71A is an enlarged view of the color sensor 71. For example, R
, G, B, (red, green, blue) constitute one pixel 71B. When main scanning is performed in the direction of arrow P, a color image is read by moving the sensor 71 using a motor or the like.

[Problem to be Solved by the Invention 1] When reading, for example, the edges of black characters printed on a white background with this type of device, a black edge 81 may appear in the center of one pixel, as shown in FIG. be. At this time, for pixels a and C, the data obtained by reading the image is output without any erroneous judgment, but for pixel A, since the B filter is in the black area 82 and the R is in the white area 93, it is judged as neither black nor white. As a result, the edges 81 of black letters are printed in a different color, and the letters become thinner.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a device that reproduces black and white image areas, particularly black character areas, with high definition using a simple configuration.

[Means for Solving the Problem] In order to achieve such an object, the present invention divides one pixel into at least two cells having different color filters, and divides the output of each divided cell into In a color document reading device that reads a color document as color separation information of the document, when outputting a color image, one pixel corresponds to the color information of one output pixel, and when outputting a single color, the color document is divided into at least two cells. output pixel
Make it correspond to the pixel.

[Function] In the present invention, a document is divided into a color image area and a black-and-white image area, and processing is changed based on signals of the divided areas. Also, R,G.

When a color sensor with color filter B scans a black and white image area, each sensor output can be regarded as a black and white luminance output, and can be read at a pixel density three times that of the color area, so the same Although a color sensor is used, a higher definition image can be obtained in a black and white image area.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of a schematic configuration according to the present invention. Here, 1 is a color line sensor, and IA is an enlarged part of it. The sensor 1 includes a photoelectric conversion element such as a CCD (charge-coupled device) and a color separation filter IC.
For example, if main scanning is performed in the direction of arrow P, a color image can be read by moving sensor 1 in a direction perpendicular to this using a motor (not shown). , RlG, B, - in the main scanning direction
It is assumed that the set is read at a pixel density of 400 dpi with one pixel IB.

The image signal output from the sensor 1 is manually input to the A/D converter 2, and the R, G, and B signals are digitally converted into R, G, and B signals.
, G, B, are converted into signals.

The image signal output from A/D converter 2 is 40
It is input to the 0dpi-1200dpi switching circuit 3.

This switching circuit 3 outputs the self-ejection area signal 110 from the black and white area signal generator 8.
It is designed to switch between pi processing and pi processing.

The color area and monochrome area of the document are specified in advance using a specifying means such as the digitizer 9. When the sensor 1 is scanning a color area, the image data is R, G, B,
The data is directly input to the density conversion color masking circuit 4 as parallel data.

On the other hand, when sensor 1 is scanning a black and white area, R, G, B, and parallel data are changed from G to B by the black and white area signal.
→R is serially converted and input as a Bk (black) signal to the gradation correction circuit 6. 400dpi -12 mentioned above
Details of the 00 dpi switching circuit will be described later.

The C (cyan), Y (yellow) and M (magenta) signals outputted from the density conversion/color masking circuit 4 undergo undercolor removal in the undercolor removal circuit 5 and are output to the gradation correction circuit 6. C and M output from the undercolor removal circuit 5
, Y, and Bk (No. 3 is subjected to gradation correction in the gradation correction circuit 6 and printed in the printer 7.

FIG. 2 is a schematic diagram of the monochrome area signal generator. Here, 12 is a color image 12A as shown in FIG. 2 (8).
and black characters 12B b<This is a mixed document and is set on the digitizer 9. Arrow P indicates the main scanning direction, and arrow Q indicates the sub-scanning direction. The digitizer 9 is connected to the microcomputer 14 via a communication cable 16, so that the coordinates designated by the digitizer 9 are sent to the microcomputer 14.

Reference numeral 13 denotes a bitmap memory, and each coordinate of the two-dimensionally arranged memory stores 1 bit of data. Further, the coordinates of the digitizer 9 and the coordinates of the bitmap memory 13 have a one-to-one correspondence. These are connected by a microcomputer 14 and a bus 17, and can be read and written freely.

15 is an address generator. +80 is a sensor drive synchronization signal manually input to the address generator 15.

A black and white area on the original 12 that you want to clearly display, such as a character area, is designated as area 1 by point A (
a, b) and point B (c, d), point C (as region 2)
e, f) and point D (g, h). Each area is a rectangle whose diagonal is a straight line connecting these two points. By sending the Pill at the specified point mentioned above to the microcomputer 14, the microcomputer 14
The area is written on the bitmap memory 13 according to the flowchart shown in FIG.

Hereinafter, the processing procedure of the embodiment of the present invention will be explained according to the flowchart shown in FIG. The digitizer 9 sends a set of two human images, which are checked in step S1. In step S2, the maximum and minimum values in the X-axis direction are determined as XMA and XMI, respectively, from the two manually entered coordinates. In step S3, Y M
A + Y M I are calculated in the same way.

In steps 34 to S8, the coordinates (XMA, YMI) are changed sequentially from the coordinates (XMl, YMI) as the starting point.
1" is written on the bitmap memory 13 until then.

In step S9, whether or not to designate the second area is displayed on an operation unit (not shown), and if the second area exists, the process from step S1 is repeated again using coordinates manually.

By the above-described processing, the area is displayed in the form of "1" in the diagonally shaded portion of the bitmap menu 13 shown in FIG. 2(A) and "0" in the other portions, for example.

Next, the sensor 1 starts scanning, and in response to the sensor drive synchronization signal 180, the bitmap information at each scanning point is sequentially read out by the address generator 15, and the black and white area signal 110 is generated by reading out the bitmap information continuously. ing. The situation is shown in FIGS. 4(A) and 4(B). When the sensor l is scanning the position ■ on the original 12, the signal waveform of the black and white area signal +10 becomes as shown by the symbol ■ in FIG. If so, the signal is shown in Figure 4 (B) with the symbol
It will be shown as follows.

When the sensor 1 and the above-mentioned area No. 18 110 are scanning the color area, that is, when the area signal is Low, the image data is sent to the next block as R, G, B color parallel data.

On the other hand, when the sensor is scanning a monochrome image area and the area signal is High, the R, G, and B color parallel data are serially converted in the order of BG→R and output. The sensor 1 used in this example is R-4 as described above.
It is a line sensor in which one pixel is an array of 0-B, and color images are read at a pixel density of 400 dpi.

If the document is black and white, the sensor outputs are R and G.

There is no need to receive it as the spectral output of RoG, B,
The output can be viewed as a black and white luminance output, and B-
By setting the serial data in the order of G-R, it is possible to read data from 400 dpi when reading a color image to 1200 dpi, which is three times as much when reading a monochrome image. This makes it possible to reproduce images with higher density and fidelity in black and white areas.

FIG. 5 shows a schematic diagram of the internal circuit configuration of the 400 dpi-1200 dpi switching circuit. The R, G, B signals input manually from the A/D converter 2 (see Figure 1) are sent to the selector 19.
R, 19G and 19B are each manually operated.

Selectors 19R, 19G and 1'lB are black and white area 43
If the signal No. 110 is Low, that is, the reading signal of the color image area, it is sent as is to the next stage of processing as R, G, B color data, and the black and white area signal 110 is the old gh
At this time, data is sent to latch circuits 20R, 20G, and 20B.

The data output from the latch circuits 2OR, 20G, and 20B are converted into density and black by lookup tables 21R, 21G, and 21B in order to correct variations in R, G, and B filter sensitivity and obtain an appropriate gray scale. Sensitivity correction is performed.

The data that has undergone density conversion and black sensitivity correction is sent to the selector 22.
This is where the parallel data is converted into serial data. As shown in FIG. 5(B), the selector 22 determines the signal to be selected for Q from the data manually input to SO and SI.

24 is a counter, and outputs A and B output the count number in binary. This counter 24 sets the clock to ``2''.
It is automatically reset when counting up to ``, and the selector is switched by counting (:Lock 260) with a cycle of 1/3 of Video C1lock 250.

A timing chart at this time is shown in FIG. R,G
, B. The parallel signal is sent pixel by pixel at 400 dpi reading in synchronization with Video C1ock250. This is selected by C1ock 260 with a cycle of 1/3 of Video C1ock 250 and serially converted, resulting in 1200 dpi reading.

The above-mentioned B-4G→R serial conversion signal is temporarily latched by the latch circuit 23 shown in FIG.
Output as 0. This signal 270 is subjected to appropriate manual correction in the gradation correction circuit 6 shown in FIG. 1, and then output to the printer. At this time, the printer also receives the black and white area signal 110 manually, so that black is printed at three times the pixel density.

On the other hand, in the case of color areas, the resolution is 400 dpi as shown in Figure 1.
-1200dpi switching circuit 3 is through and 400dpi
R, G, and B color image processing is performed with pi as it is. The signal output from the switching circuit 3 is input to a color correction circuit including a density conversion/color masking circuit 4 and the like. Data when reading CCD is luminance signal R, G, B,
Here, processing is performed to convert into complementary color density signals of C (cyan), 1M (magenta), and Y (yellow), which absorb R, G, and B wavelengths independently. Also, C1
Masking calculations are also performed to match the spectral reflection characteristics of the M and Y coloring materials.

Next, processing is performed in the undercolor removal circuit 5 to remove the gray component. This is C,M.

It is well known that printing Y only causes the problem of low density in black areas. Therefore, we remove the gray component and use that component as a Bk signal for Y, M, C, B
The above problem is addressed by printing in K4 colors. Thereafter, appropriate tone correction is performed in the tone correction circuit 6 and output to the printer.

[Effects of the Invention] As explained above, according to the present invention, by regarding the color sensor as a black and white sensor, it is possible to obtain a high-definition image of a black and white area such as a character area in a color document. There is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the overall configuration of an embodiment of the present invention, FIG. 2 is a schematic diagram of a black and white area signal generator of an embodiment of the present invention, and FIG. 3 is a flowchart showing an example of a processing procedure of an embodiment of the present invention. Fig. 4 is an explanatory diagram of area signal generation in the embodiment of the present invention, Fig. 5 is an explanatory diagram of the 400 dpi - 1200 dpi switching circuit in the embodiment of the invention, Fig. 6 is a timing chart of the switching circuit, and Fig. 7 is a conventional color image FIG. 8 is an explanatory diagram of a reading device when reading a conventional black edge. 1...Color sensor, 2°...A/D converter, 3...400dpi -1200dpi switching circuit, 4
... Density conversion/color masking circuit, 5... Under color removal circuit, 6... Gradation correction circuit, 7... Printer, 8... Black and white area signal generator, 9... Digitizer, 12... Original, 13... Bit map memory, 14... Microcomputer, 15... Address generator, 16... Communication cable, 17... Bus, 19R, 19G, 19B... selector, 2OR, 20
G, 20B, 23... latch circuit, 21R, 21G,
21B... Lookup table, 22... Selector, 24... Counter. Goyasu Shikokukai is also an explanatory diagram of area signal generation in Embodiment 1 of the present invention. Figure 4. Construction diagram of a conventional device. Figure 7.

Claims (1)

[Scope of Claims] 1) A color document reading device that divides one pixel into at least two cells having different color filters and reads a color document using the output of each divided cell as color separation information of the document. When outputting a color image, the one pixel corresponds to color information of one output pixel, and when outputting a single color, the pixel divided into the at least two cells corresponds to one output pixel. A color image reading device featuring: