JPH06113143A - Picture processing system - Google Patents

Abstract

PURPOSE:To execute a picture processing at positions different by colors in the same picture and to improve the compression rate of the picture through the use of color correlation by providing a time division means in a compression picture memory part and providing a mechanism for time-divisionally executing a masking-processing for respective print color components. CONSTITUTION:Color picture data at the same position of a picture element are simultaneously compressed, and the data are once accumulated in the compression picture memory. Then, the picture is transmitted, color picture data at the different position of the picture element are simultaneously read or at other time so as to extends them and the picture is outputted. Namely, a data read means is time-divisionally provided for the picture compression memory, and data extension/data distribution functions are time-divisionally given to picture extension parts 17 and 18 and a making processing part 21. Thus, the picture processing can be executed at the positions different by the colors in the same picture, and the compression rate of the picture can be improved by using color correlation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing system.

More specifically, the present invention is suitable as an image processing technique for printing a compressed image, and is applicable to, for example, a technique of outputting an image to a so-called 4-drum color printer. It relates to a processing method.

[0003]

2. Description of the Related Art FIG. 8 shows a simple configuration example of a four-drum type laser color printer using four developing drums. In the figure, the laser drivers 23 to 26 are supplied with corresponding color data Y (yellow), M (magenta), C (cyan), and BK (black) for color development. The lasers 101-104 form latent images on the photosensitive drums 109-112 based on the signals given to the laser drivers 23-26.

The latent image formed on each drum is the developing device 10.
5 to 112, and an image is formed on each drum.

The recording paper (transfer paper) 113 is a conveyor belt 11.
4 and then passes under the developing devices 109 to 112 in order, and at that time, the toners of respective colors are transferred onto the paper, and the developers (toners) for the four colors are transferred in the same phase on the paper. Fix through the fixing device.

At this time, in order to prevent the four colors from having the same phase on the paper, that is, registration deviation,
Distance Rmm between each drum

[0007]

[Outer 1]

Image data must be given to each laser driver 24, 25, 26.

Therefore, conventionally, the image memory has been used to delay the image data. Therefore, it was difficult to commercialize it due to cost increase.

It can be easily inferred that the image can be compressed and buffered in order to prevent the cost increase of the apparatus due to the image memory capacity.

FIG. 9 shows an example of a circuit configuration when image compression is not performed. In the figure, the image data input from the image input device 131 is subjected to color correction processing for the printer by the masking unit 132, and then the image memories 133 to 1
The image data is input to 36 and the image data is stored.

Thereafter, the image data of each color component in the image memories 133 to 136 is read by the delay counters 128 to 130 after a predetermined delay time, and the laser drivers 23 to 130 are read.
It is sent to 26 for imaging.

FIG. 10 is also similar, and shows an example in which the image input device is a scanner. That is, in order to perform real-time processing according to the operation speed of the scanner 1,
The cyan color component (C) is subjected to an image processing operation such as masking in the image processing unit 115 and directly sent to the laser driver 23. The other color components are appropriately delayed by the delay devices 141 to 143, and then data-supplied to the laser drivers 24-26 to form an image. Delay devices 141 to 14
3 can be composed of a normal memory, a FIFO memory, or the like.

FIG. 11 is an electric circuit block diagram showing an example where the image compression technique based on FIGS. 9 and 10 is applied as it is. In the figure, the image read by the scanner 1 is subjected to various kinds of processing such as γ (gamma) conversion in the image processing unit 115. Image processing unit 115
Then, from the R, G, B data from the scanner 1, Y, M,
Luminance / density conversion to C and BK data is also performed. Then, the images are compressed by the image compression units 116 to 119 due to the image delay and temporarily stored in the compressed image memories 120 to 123.

Thereafter, the data in the compressed image memories 120 to 123 are read and sent to the image decompressing units 124 to 127, and the image data decompressed in the images are laser drivers 23 to.
26. At this time, the delay counters 128 to 13
The image decompression unit 125 decompresses according to the delay time by 0.
~ 127.

Therefore, the image compression unit 116 and the image memory 1
20. The image decompression unit 124 can be omitted.

[0017]

However, in the configuration example using the conventional image compression technique as described above, the image compression unit is provided for each color, and the image is decompressed separately for each color. This is because the delay time of image data differs for each color.

For this reason, the image compression section cannot improve the compression efficiency by using the compression utilizing the color correlation, and also from the three color system of R, G, B to C, according to the number of developing colors.
The four-color system of M, Y, and BK is a factor that further increases the amount of compressed data.

On the decompression side of the image, since the raw data memory is omitted and decompression is performed according to the print output, the position of the obtained color data is completely different on the screen, and image processing using color correlation is not possible. I couldn't do it at all. Therefore,
If the image data is sent to different types of printers, color correction processing is also impossible. Here, as the processing utilizing the color correlation, there are a large number of color correction processing of the printer, color conversion processing for performing color discrimination and conversion into another color, and the like.

Therefore, in view of the above points, an object of the present invention is to provide an image processing system capable of performing highly efficient and multi-functional color image processing in spite of its simple structure.

[0021]

In order to achieve the above object, the present invention compresses color image data at the same pixel position at the same time, and temporarily stores some or all of the data in a compressed image memory. In some cases, image transmission is performed, and color image data at different pixel positions are read out at the same time or at another time, expanded, and output as an image.

[0022]

According to the above configuration of the present invention, the image compression memory is provided with the data reading means in a time division manner, and the image decompression section and the masking processing section are also provided with the data decompression and data distribution functions in a time division manner. An image can be compressed and expanded using a color space having high compression efficiency, and it is not necessary to have a plurality of image processing circuits for each color.

It is also possible to transmit the compressed image data once accumulated to another printer and perform color correction processing specific to that printer.

[0024]

EXAMPLES Examples of the present invention will be described in detail below.

1 and 2 are views showing an embodiment of the present invention. In the figure, the three-color separated signals R, G, B read by the image reading scanner 1 are input to the image processing unit 2. Here, edge enhancement processing suitable for a digital copying machine, trimming processing, and other various image processing are performed. The output is converted into another color space by the color conversion unit 3.

In this embodiment, Y, C are taken into consideration in consideration of compression efficiency.
Convert to _r , C _b space. This conversion is a linear conversion, and the following conversion is performed.

[0027]

[Equation 1]

The inverse transform is obtained by the following equation.

[0029]

[Equation 2]

Of the Y, C _r , and C _b components of the image signal obtained by such conversion, the Y signal indicates the brightness information of the image and is a very important signal. The C _r and C _b components represent color information, and their gradation is a very important signal, but in terms of resolution, considering the redundancy of human eyes, it is about half that of the Y signal. It is also possible to drop it.

Therefore, the output C _r and C _b components of the color conversion section 3 are reduced in horizontal resolution or both horizontal and vertical resolution to about half in the sub-sampling sections 4 and 5.

The outputs of the sub-sampling units 4 and 5 are synthesized by a synthesizer 6, and C _r and C _b are alternately arranged to produce an image compressing unit 8.
Compressed with.

On the other hand, the Y signal is compressed by the image compression section 7. The compressed data in the image compressing section 7 and the compressed data in the image compressing section 8 are alternately arranged, and the compressed image memory 1 is collected as one unit.
Input to 0.

When the horizontal resolution is halved in the sub-sampling units 4 and 5, Y, C _r , Y, C _b , Y, C _r , Y, C _b
, And so on, and when the horizontal and vertical resolutions are halved in the sub-sampling units 4 and 5, Y, Y, C _r , Y, Y, C
_{The order is b} , Y, Y, C _r , Y, Y, C _b , Y, Y, C _r , ....

At this time, the addressing of the memory is performed by the address counter 9, and the address of the compressed image memory 10 is set to 0.
Data is stored in order from the address. When outputting the image from the printer, the address generators 12 to 15 count the addresses.

The start of counting in the address generators 12 to 15 is controlled by the delay timing generator 11, and the drum phase distances R _M , R _C , and R _K for each color are divided by the paper feed speed Vmm / sec. A start delay of _M , t _C , t _K is performed.

Therefore, the address generators 12 to 15 do not count the address until the count is started, and the initial address is output. Address generators 12-15
Correspond to signal generation timings for Y, M, C, and BK, and are sequentially selected by the selector 16 and input to the compressed image memory 10. Therefore, the compressed image memory 1
As the output A of 0, data to be decoded is output in the order of Y, M, C, and BK, and is supplied to the image decompression units 17 and 18.

The Y component (luminance) is input to the image expansion unit 17, and the C _r and C _b components which are color components are input to the image expansion unit 18 and expanded. Both of these image decompression units 17 and 18
Decoding for Y, M, C and BK is sequentially performed in time division.

Since the output of the image expansion unit 18 is sub-sampled, the expansion unit 20 outputs the C _r component, C _b.
The number of pixels is increased for both components. The principle is performed by normal image enlargement processing and linear density conversion processing, and is not particularly noteworthy.

The data decompressed in this way is input to the masking circuit 21, where Y (luminance), C _r , and C _b.
To Y (yellow), M, C and BK.

In this masking circuit, as shown in FIG. 3, a color conversion circuit 27 first converts Y (luminance), C _r , C _b into R, G, B, and a color masking circuit 28 converts C, It is for conversion into M, Y and BK. The color masking circuit 28 performs conversion from luminance to density and color correction according to the color material of the printer.

The output of the masking circuit 21 is input to the distributor 22, which converts serial data input in Y, M, C, and BK in time division into parallel data, and is delayed by the delay timing generation unit 11. The leading edge of the image is cleared to zero for color components that have not yet been output to prevent the laser driver from operating.

Similarly, in the image decompression units 17 and 18, the delay timing generation unit 11 controls the signal components not shown so as not to decode the color components that are not the leading edge of the image.

FIG. 4 shows another embodiment of the peripheral portion of the masking circuit 21. In this embodiment, the color conversion circuit 2
7, the Y (luminance), C _r , and C _b signals are R, G, and B.
After being converted into, the serial time-division signals are converted into parallel signals for each developing color by the distributor 30, and the one-color masking units 31 to 34 generate signals for Y, M, C, and BK. Given as data.

In the one-color masking sections 31 to 34, Y,
Masking, which is color correction corresponding to each color of M, C, and BK, is performed, and the processing result is given to the laser drivers 22 to 25 to form an image.

The one-color masking section is constructed as shown in FIG. 5, and since the output color is only one color, it can be constructed with a circuit scale of about 1/4 as compared with the masking circuit 21 which masks four colors simultaneously.

The input R, G, B signals are logarithmic conversion unit 4
1, 42, 43 convert the luminance data into density linear data Y (yellow), M, C. Further, the values of the primary conversion matrix are set in the coefficient registers 44, 45 and 46.

[0048]

[Equation 3]

With such masking, in order to obtain the masking result of cyan C, d ₁₁ , d ₁₂ , and d ₁₃ may be set in the coefficient registers 44, 45, and 46, respectively.

Similarly, to obtain a magenta (M) masking result, d ₂₁ , d ₂₂ and d ₂₃ are set, and a yellow (Y) result is set to d ₃₁ , d ₃₂ and d ₃₃ . And the multipliers 35 and 3
UCR for subtracting the black component by subtractor 40
(Undercolor removal) processing is performed to obtain final data.

For the black signal (BK) generation, the outputs C, M, Y of the logarithmic conversion units 41, 42, 43 are input to the black generation unit 38, and the black data is generated based on the minimum value of the C, M, Y signals. Is generated.

Therefore, the black generation unit 38 may be provided in any one of the one-color masking units 31 to 33. In that case, the one-color masking unit 34 is omitted and the one-color masking units 31 to 31 are omitted. Any one of the outputs of 33 may be used.

The data input to the black generator 38 is
The outputs C, M, and Y from the logarithmic conversion units 41, 42, and 43, and the adder 39 in the one-color masking units 31, 32, and 33
You may use the output from. In that case, the one-color masking unit 34 can be configured by only the black generation unit 38.

FIG. 6 shows the masking circuit 21 shown in FIG.
The color masking circuit 2 of FIG.
8 is a concrete circuit showing 8 in more detail.

The basic structure is similar to the one-color masking section shown in FIG. The multipliers 58, 59, 60 are multipliers for the primary matrix operation, and in the logarithmic conversion unit 51,
The data converted from R, G, B to C, M, Y and the primary matrix coefficient are multiplied. At that time, the primary matrix coefficient data is supplied from the selectors 55, 56 and 57, but the coefficient registers 52, 53 and 54 are respectively C, M and
It has three types of coefficients for Y calculation.

The coefficient register 52 has the above-mentioned d ₁₁ , d ₂₁ , and d.
₃₁ , the coefficient register 53 stores d ₁₂ , d ₂₂ and d ₃₂ , and the coefficient register 54 stores d ₁₃ , d ₂₃ and d ₃₃ . Here, in _dij , the selectors 55 to 55
The selection is made in order at 57.

Therefore, according to the order, the output result of the adder 61 is d ₁₁ · C + d ₁₂ · M + d ₁₃ · Y, d ₂₁ · C + d _22.
・ M + d ₂₃・ Y, d ₃₁・ C + d ₃₂・ M + d ₃₃・ Y are output in this order, and finally the black component is subtracted by the subtractor 40 and U
CR is performed. At that time, the black component is generated in the black generation unit 38 from the data of the logarithmic conversion unit 51.

Therefore, with such a configuration, by synchronizing with the output color of the data after serially decompressing the image, the masking processing for four colors is performed by one masking circuit to the masking circuit for one color. It is feasible on a scale that does not change much.

FIG. 7 shows another embodiment of a circuit for outputting C, M, Y and BK signals from Y (luminance), C _r and C _b components.

In the circuit shown in FIG. 7, the luminance is converted to the density after the masking process for the printer is performed. The Y (luminance), C _r , and C _b signals output from the image expansion unit 17 and expansion unit 20 shown in FIG. 2 are input to the primary matrix calculation unit 65, and R ′, G ′, and B ′ are obtained. To be
The R ', G', and B'signals are the color-corrected signals of the printer, and the logarithmic conversion units 66 to 68 respectively generate C and C'signals.
Converted to M, Y.

For the black data K, the black generation unit 38
In, it is generated based on the outputs of the logarithmic conversion units 66 to 68.

In the case of this configuration, since the logarithmic conversion is performed later, the primary matrix operation processing from the Y, C _r , C _b to the R, G, B space and the printer for the R, G, B color signals are performed. There is an advantage that the primary matrix calculation process for the color correction process can be performed at once by the same circuit.

[0063]

[Equation 4]

[0064]

[Equation 5]

If

[0066]

[Equation 6]

Therefore, in the case of an arithmetic unit capable of performing a primary matrix operation, R ', G', B'are generated from Y, C _r , C _b depending on the coefficient setting.

In the extreme example of this embodiment, Y, M,
When the C and BK drums 109 to 112 are widely separated,
In this case, only one color is valid at the same time in the image expansion units 17, 18 and the like.

If this is expanded, the present invention can be applied even when the printer is a complete frame sequential recording system (for example, a thermal transfer system). At this time, if the four-color development data is processed by time division, there is no problem even if the time division mechanism is removed.

[0070]

As described above, according to the present invention, the compressed image memory section is provided with the time-division processing means, and the mechanism for performing the time-division masking processing for each print color component is provided. It is possible to perform image processing at different positions for each image, and it is possible to increase the image compression rate by utilizing color correlation. Moreover, a specific circuit configuration can be realized without increasing the circuit scale.

Further, in order to compress and expand each color component at the same time, it becomes possible to have various kinds of image processing relating to color after expansion, that is, on the printer side, and the possibility of utilizing digital image processing technology is widened.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment (first half portion) of the present invention.

FIG. 2 is a block diagram showing an embodiment (second half) of the present invention.

FIG. 3 is a block diagram showing a detailed configuration of a masking circuit.

FIG. 4 is a block diagram showing another embodiment forming a peripheral portion of the masking circuit.

FIG. 5 is a block diagram showing a configuration of a one-color masking unit.

FIG. 6 is a block diagram showing a specific configuration example of a masking circuit.

FIG. 7 is a block diagram showing a specific configuration example of a masking circuit.

FIG. 8 is a schematic configuration diagram of a 4-drum type color printer.

FIG. 9 is an explanatory diagram of a conventionally known color printing technique.

FIG. 10 is an explanatory diagram of a conventionally known color printing technique.

FIG. 11 is an explanatory diagram of a conventionally known color printing technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 image reading scanner 2 image processing section 3 color conversion section 4, 5 sub-sampling section 6 synthesizer 7, 8 image compression section 9 address counter 10 compressed image memory 11 delay timing generation section 12-15 address generation section 16 selectors 17, 18 Image expansion unit 19 Distributor 20 Enlargement unit 21 Masking circuit 22 Distributor 23 to 26 Laser driver 27 Color conversion circuit 28 Color masking circuit 30 Distributor 31 to 34 1 color masking unit 35 to 37 Multiplier 38 Black generation unit 39 Adder 40 Subtractor 41-43 Logarithmic converter 44-46 Coefficient register 51 Logarithmic converter 52-53 Coefficient register 55-57 Selector 58-60 Multiplier 61 Adder 65 Primary matrix calculator 66-68 Logarithmic converter 101-104 Laser 105-108 Developing device 109-112 Photosensitive drive Paper 113 Paper transport belt 115 Image processing unit 116 to 119 Image compression unit 120 to 123 Compressed image memory 124 to 127 Image decompression unit 128 to 130 Delay counter 131 Image input device 132 Masking unit 133 to 136 Image memory 141 to 143 Delay apparatus

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 1/46 9068-5C

Claims (5)

[Claims] 1. Color image data at different pixel positions by simultaneously compressing color image data at the same pixel position, temporarily storing a part or all of the data in a compressed image memory, and then transmitting the image in some cases. An image processing method characterized by reading out at the same time or at another time, expanding the image, and outputting the image. 2. The image processing method according to claim 1, wherein when color image data at different pixel positions are processed at the same time, the same circuit is used for time division. 3. The image processing method according to claim 1, wherein color correlation is used in the image compression / decompression method to improve the compression rate. 4. The image decompressing unit according to claim 1, time-divisionally processes a developing color required for color recording at a certain time t _n , and simultaneously outputs all color components for each printer position of each developing color. An image processing method characterized by: 5. The image processing method according to claim 1, wherein after image expansion, image processing using color correlation of the three primary colors is performed for each position where development is performed simultaneously.