JPS63191474A - Masking processor - Google Patents

Abstract

PURPOSE:To perform a proper masking process by an inexpensive device by masking color sequential color image data consisting of plural color component signals as it is. CONSTITUTION:Respective chrominance components from a CCD line sensor 100 are converted by an analog-digital converter 110 into digital values in order. The A/D converter 110 outputs digital data in the order of B, G, R, B, G, R,.... The obtained digital data are converted by a complementary color converting circuit 120 into complementary color data Y, M, and C and outputted in the order of Y, M, C, Y, M, C.... The obtained color sequential color image data are sent to an image delay part 201, and through image data, one-clock delayed image data, and two-clock delayed image are sent to a masking part 202 respectively. The masking part 202 corrects the color blur of output ink.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a masking processing device that digitally processes a color image.

[Description of prior art]

Conventionally, for example, in digital color copying machines, each color R4G,
After reading the H data and converting the read image data into digital signals, the data is processed and an image is formed using a laser beam printer, liquid crystal printer, inkjet printer, etc.

And read in such data processing.

In order to correct the color characteristics of writing, color correction (masking) processing is normally performed on input color image data.

Masking processing is performed, for example, by processing data (R, G, B or Y, M) within arbitrarily determined pixels of input R, G, B or Y, M, C color image signals.

In C), masking calculations for color data of each color within a pixel are performed in parallel. However, when performing parallel processing, there is a drawback that the circuit scale becomes large.

In addition, in a system that reads images with a sensor in which sensors of each color are arranged in-line and forms color image data sequentially, proper masking cannot be achieved if masking processing is performed within arbitrarily determined pixels. There was a drawback. For example, when black line data is read across two pixels as shown in FIG. 1a, there are pixels in which only blue is read, and pixels in which red and green are read. Naturally, when masking is performed within a pixel, there is a drawback that only yellow, which is the complementary color of blue, is output even though each pixel originally reads black data.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional example, and is a masking processing device that performs real-time processing of inputted color sequential color image data as it is color sequential without having separate circuits for each color, and performs appropriate masking processing. The purpose is to provide.

〔Example〕

FIG. 1b shows a color image processing block diagram of this embodiment.

In the figure, a CCD line sensor 100 is a CCD line sensor that detects the R, G, and B components of a document, and is an in-line sensor in which RGB sensors are sequentially arranged. Each color signal from the line sensor is sequentially converted into a digital value by an analog-to-digital converter 110.

"CA/D converter 1], 0 is B, G, R,
B, G.

Digital data is output in the order of R...

The obtained digital data is converted into complementary color data Y, M, and C by the complementary color conversion circuit 120.

Y, M, C... are output in this order.

The obtained color sequential color image data is sent to the image delay unit 201.
The through image data, the image data delayed by one clock, and the image data delayed by two clocks are sent to the masking section 202, respectively.

The masking unit 202 is a circuit for correcting cloudiness in the output ink color, and performs calculations as shown in the following equation.

Y1' =a HY1+a 12 M, +a 13 C
OJ' ==a 21 Y1+a 22 M, +a 2
3 C3C1' ``a 3) Y2'+ a 32
Ml+a 33 c.

co! y, + MI + CI + Y2
'Input data y, // M,', C,'
: Output data These nine coefficients are output by the control unit 200.
After the ink cloudiness is corrected by the masking unit 202 determined by a blank masking control signal, the ink is sent to the time axis conversion unit 203. Since the input image data and the subsequent image data have different frequencies, the time axis conversion unit 203 performs frequency conversion according to the time axis conversion control signal sent from the control unit 200 and outputs the result. . The output serial image data is input to the black extraction section 204. Y, M in one pixel.

In order to use the minimum value of C as black data, the black extraction unit 204 uses Y
, M, and C are detected. The detected black data is input to the TJCR section 205.

The UCR unit 205 subtracts the extracted black data from each of the Y, M, and C signals. Furthermore, black data is simply multiplied by a coefficient. After correcting the time difference between the black data input to the UCR unit 205 and the image data sent from the masking unit 202, the following calculation is performed.

Y'=Y-a, Bk M'=M-a2Bk C' = C-'a3Bk Bk' = a4Bk Y, M, C, Bk Two extractors, input data Y
', M', C', Bk: extraction section, output data coefficients (al, a2.a3.a4) are determined by the UCR control signal sent from the control section 200.

The data output from the UCR unit 205 is then γ.

The signal is input to offset section 206 .

At the γ, offset 206, gradation correction is performed as shown in the following equation.

y' = b, (y-c,) M' = b2 (M-02) C' -b3 (CC3) Bk' = b4 (Bk C4) Y, M, C, B
k: γ, offset section input data Y', M', C', Bk: γ, offset section ratio output data, coefficients (b+~b4.c, ~C4) in the above equation are γ sent from the control unit 200. , determined by the offset control signal.

The signal gradation-corrected by the offset 206 is then sent to the line buffer 20 which stores image data for N lines.
7 will be powered by humans. This line buffer 207 outputs 5 lines of data necessary for the subsequent smoothing and edge emphasis section 208 in 5 lines in parallel according to the memory control signal sent from the control section 200. These 5 lines worth of signals are input to a spatial filter whose filter size is variable according to a filter control signal from the control unit 200, and smoothed.
Edge enhancement is then performed. In smoothing, image noise is removed by using the average value of the pixel of interest and surrounding pixels as the density value of the pixel of interest. Also, as shown in Figure 2, the difference between the pixel data of interest and the smoothed signal is used as an edge signal,
Edge enhancement is performed by adding this to the pixel data of interest. A detailed explanation of the smoothed edge enhancement unit 208 will be given later.

The image data output from the smoothing and edge enhancement unit 208 is input to a color conversion unit 209, and color conversion is performed in response to a color conversion control signal from the control unit 200.

The color to be converted, the color to be converted, and the area in which the signal is valid are input in advance using a digitizer device or the like, and the color conversion unit 209 replaces the image data based on the data. In this embodiment, the color conversion unit 209
A detailed explanation will be omitted. Smoothing and edge enhancement section 208
The image signal outputted from the image signal converter and the image signal after color conversion are input to the selector 210, and the image data to be output is selected by the selector control signal 2. Which image data to select is determined by specifying the valid area input from the digitizer device or the like. The image signal selected by the selector 210 is input to the buffer memory 110 and the binarization processing section 108 in FIG.

A description of the system input to the buffer memory 110 will be omitted here.

The binarization processing unit 108 will be explained. The image data input to the binarization processing section 108 is input to the dither section 2 in FIG.
11, Y, M, C, Bk are input serially in the order of 8 bits.

The dither unit 211 uses 6 bits in the main scanning direction for each color.
.

It has a memory space of 6 bits in the sub-scanning direction, 4 bits in the main scanning direction, and 8 bits in the sub-scanning direction, and the dither matrix size and the dither threshold value in the matrix are set by a dither control signal from the control unit 200. When the dither circuit is in operation, the mechanical main scanning direction counts the 1-line image reading interval signal of the CCD line sensor, and the sub-scanning direction counts the image video clock, and reads out the set dither threshold value in the memory space. Also, this memory space can be serialized as Y and M.

A serial dither threshold value can be obtained by switching between C and Bk. Next, this threshold value is input to a comparator (not shown) and compared in size with image data input from the selector 210.

The output from the comparator is as follows: image data>threshold: 1 image data≦threshold 20. This data is then output as parallel 4-bit data in the serial-parallel converter.

Next, specific circuits of each processing device shown in FIG. 1b will be explained in detail below.

First, the data delay section 201 will be explained. The data delay section 201 includes a flip-flop 3 as shown in FIG. 3a.
It is composed of two flip-flops 01 and 302, and outputs through image data, image data delayed by two clocks, and image data delayed by two clocks.

Each color sequential color image data then enters a masking section 202 .

In the masking section 202, table conversion is performed using multiplication table RAMs 220 to 222, as shown in FIG. To explain using FIG. 36, the three types of color sequential color image data input to the masking unit 202 are stored in three types of RAMs 220 to 222, respectively.
It is input to M. In the input color sequential color image data, coefficients are changed for each color based on color information from the control unit 200. As a result, for through image data,
a 12 Ml, a 23 C1.

a3. For image data delayed by Y2.1 clock, a Hy, , a22 M, , a33
c, , for image data delayed by two clocks,
a13 c, o, 1a21 y, , a32
M, is obtained in this order. Thereafter, by performing addition in the adder 223, masking of the desired data using the previous and previous image color data is performed as described below.

Yl' -a 11 Y) + a 12 M1+
a 13 C0M,' = a 2. Y, +a 2
．． , M, +a 23C.

C1' = a 31 Y2 + a 32 M1+ a
33 C1 Next, the time axis conversion unit 203 will be explained.

The time axis conversion unit 203 is a FiF as shown in FIG. 5a.

It consists of a memory 200'(μPD42505C; manufactured by NEC Corporation). This FiFo memory 200'
has independent write and read counters built-in, and has a configuration in which writing and reading can be controlled independently.

As shown in FIG. 5b, when the reset signal R8TW, which is generated at the timing before the input of -line data, is input and the signal WE indicating the input image signal period is enabled, from address 0 of the FiFo memory, while the signal is enabled, Writing is performed sequentially. Similarly, for reading, the reset signal R8TR generated at the timing before outputting the data for the - line is input, and the read request signal RE from the output side is input.
When enabled, reading is performed sequentially from address O of the FiFo memory 200' while enabled.

Furthermore, when the RE is disabled, the read counter is held at that address, and no data is read until the RE is enabled again.

In this embodiment, as shown in FIG. 3b, during writing, the reset signal R3TW is input at the beginning of each line, and the data section W
Enable E and write sequentially from address O. Further, reading is performed from address O by inputting R3TW at the beginning of each line and disabling the portion RE where black data is inserted. Therefore, a signal DATAOUT as shown in FIG. 3b is obtained, and a vacant time for black Bk is provided. Furthermore, each FiFo control signal R3
TW, R3TR.

WE and RE correspond to time axis conversion control signals sent from the control unit 200.

Next, the black extraction section 204 will be explained using FIG. 6.

The input image data is input in the order of Y, M, C, and α (empty). Here, in the case of 8-bit image data, α is data corrected so that it becomes FFH in hex display (H). Such color sequential image data is input to a comparator 224 and a flip-flop 225. Here, when the data (FFH) of α is input, the data is forcibly held in the flip-flop 225. Next, the data held in the flip-flop 225 and the image input data are sequentially compared.

Input image data (data held by flip-flop 225) A latch pulse is sent from the latch timing generator 227 to the flip-flop 225 in response to a signal from the comparator 224, and the input image data is held. 1
When the image data (Y, M, 'C) for pixels are compared, the minimum image data of Y, M, and C held in the flip-flop 225 is held in the flip-flop 226.

In this way, extraction of the minimum values of Y, M, and C, ie, black extraction, is performed on the color-sequential image data, and the extracted black data is output.

Next, UCR will be explained using FIG. 7.

The black data enters the coefficient multiplication table RAM 228.

In addition to this, a color mode signal for color discrimination is input from the control section 200. While one pixel of black data is being input, the color mode changes to Y, M, C, and Bk. Based on this color information, the coefficient table is switched for each color, and multiplication of coefficients is performed independently for each color. The black data multiplied by the coefficient is subtracted from the image data sent in color sequentially by the next subtracter 229 and output.

Next, the γ offset portion (FIG. 8) will be explained.

In the γ offset section, the coefficient multiplication table RAM shown in FIG.
Similar to 228, the RAM 160 performs calculations as shown in the following equation.

Y' -α+ (y-β1) M' -C2 (M-R2) c' = C3 (c-R3) Bk' -C4 (c-R4) The input data is divided into tables for each color by the color mode signal. γ and offset are calculated and output for each switched color.

Next, the smoothing process will be explained using FIG. 9.

Next, the image data is stored line by line in the line buffer 207 in color sequential order. This time the filter is 5×5
Since this is performed in an area of 1, color-sequential image data is output in 5 lines in parallel. For example, to explain the smoothing process, as shown in FIG. 9, five lines of input color sequential data are added by an adder 230, and then delayed by flip-flops 231-234. Here, the flip-flops 231 to 234 are each configured to be delayed by four pixels by serially connecting four flip-flops.

This allows filtering to be performed for each color even if image data is input sequentially.

This time, the filter matrix is 5×5, but the size is not specified. The pixel data delayed in this way is sent to the adder 2.
35 and is added, the division RAM 236 calculates 1/
25 and output in color sequential order.

A description of the edge enhancement and color conversion sections will be omitted.

Further, dither will be explained using FIG. 1O.

Counters 237 to 240 are provided for each color so that dithering can be changed for each color.

The counter values for the four colors (YD, MD, CD, BkD) are converted to YD and MD by the parallel-serial converter 241.

CD and BkD are sequentially output to the dither RAM 242 in this order. In the dither RAM 242, the dither threshold value for each color is changed independently by switching the upper address based on the color information. The dither threshold values output from the dither RAM 242 color-sequentially in this manner are input to the comparator 243. The comparator 243 compares the image data sent in color sequence with the dither threshold value sent in color sequence, and after binarizing the image data, the serial-parallel conversion unit 24
2 is converted to Y.

A total of 4-bit signals, 1 bit each for M, C, and Bk, are output.

As described above, excluding masking processing, black extraction and UCR
, γ correction, dither processing, smoothing, edge enhancement processing, etc. can be performed using color sequential signals as they are.

Note that the circuit for color sequential signal processing in this embodiment can be modified in various ways.

[Explanation of effects]

As described above, according to the present invention, by performing the masking process using the color data before and after the data to be masked in the input color sequential color image data, the masking process can be performed on the color sequential color image data as it is. This has the advantage of being able to provide a masking processing device that is much cheaper than conventional ones, and also being able to perform appropriate masking processing on image data read by an in-line color sensor.

[Brief explanation of the drawing]

Figure 1a shows the configuration of the in-line sensor, Figure 1b
The figure is a block diagram of the color image processing device of this embodiment.
The figure is a timing chart of smoothing and edge enhancement processing,
Fig. 3a is a detailed circuit diagram of the data delay section, and Fig. 3b is a detailed circuit diagram of the data delay section.
Figure 4 is a detailed circuit diagram of the masking section, Figure 5a is a time axis conversion circuit diagram, Figure 5b is a timing chart of each part of Figure 5a, and Figure 6 is a diagram of the black extraction section. 7 is a detailed circuit diagram of the UCR section, FIG. 8 is a γ offset circuit diagram, FIG. 9 is a detailed circuit diagram of smoothing, and FIG. 10 is a detailed circuit diagram of the dither processing section.

Claims (2)

[Claims] (1) A masking processing device characterized by performing masking processing on color sequential color image data consisting of a plurality of color component signals as the color sequential data. (2) The masking processing apparatus according to item 1, wherein the masking process is performed using color data of a plurality of colors before and after the main color data to be masked in the input color sequential color image data.