JPH10224648A - Picture processor and picture processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a picture processing corresponding to the attribute of an input picture through the use of a look up table in few memory areas by varying the number of bits in a high-order bit signal addressing the look up table. SOLUTION: In a color signal processing block 12-1, an input signal is divided into high-order bit signals Ru1, Gu1 and Bu1 and low-order bit signals 54-1Rl1, Gl1 and Bl1 of respective colors in a bit division circuit 52-1. The high-order bit signal 3-1 is inputted as the address signal of the look up table LUT1 (55-1) storing grid point data. An output value (57-1) stored in the table, which corresponds to the high-order bit signal 53-1, is read. A product sum arithmetic circuit (59-1) generates a first output signal C1 by using the output signal value 57-1 and a weight coefficient 58-1 and it is transmitted to an interpolation circuit. Blocks 12-2 and 12-3 are similarly processed.

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 and method for performing image processing using a table in consideration of image attributes.

[0002]

2. Description of the Related Art Conventionally, there is an apparatus of this type as shown in FIG. In this method, an original image is separated into three colors of R, G, and B, and these are converted into C, M, and Y signals, which are three primary colors of subtractive color mixture, and are printed out by an inkjet printer or the like to obtain a color duplicate image. Things.

The signal processing circuits 101, 102, 103 shown in FIG.
From the input three primary color signals R, G, B to the output color signals C, M, Y
Are generated individually.

For example, in order to generate C, M, and Y signals from R, G, and B, so-called masking operations are performed at 101, 102, and 103, respectively, as in the following equations.

[0005] _{101: C = A 11 × R} + A 12 × G + A 13 × B 102: M = A 21 × R + A 22 × G + A 23 × B 103: Y = A 31 × R + A 32 × G + A 33 × B where A _ij is The coefficient is determined according to the characteristics of the output device.

Another conventional example is a signal processing circuit 10.
Rather than performing the product-sum operation as described above at 1, 102, and 103, the operation result is stored in a table memory in advance, and the operation result is read from the table for the input R, G, and B signal values. An output method is also being considered. However, in this case, if the input signal is represented by 8 bits for each color, 2 ²⁴ addresses (that is, 1600 addresses)
), Which is not practical.

Therefore, there is another conventional example shown in FIG. This divides the input R, G, B signals into upper bit data 111 and lower bit data 112,
The table memory 113 stores only the operation result for the upper bit, and the output value 114 for the upper bit data is linearly interpolated with the lower bit data (115).
Thus, a final output signal 116 is obtained. The table storage memory by doing this will be sufficient if only have addresses that are required by the number of bits of the upper bits, for example, upper bit and stored for each color 3 bit them if 2 ⁹ address (i.e. 512 address) This means that only the area is sufficient, and the storage area can be significantly reduced.

[0008]

In the prior art described above, an input color separation signal represented by three colors of R, G, and B is converted into an output color signal in accordance with a predetermined arithmetic expression. The optimum value of the arithmetic expression required here differs depending on the attribute of the entire image to be input, and it is inconvenient to apply a uniform arithmetic expression to an arbitrary input signal.

For example, an original image 121 as shown in FIG.
Is color-separated into three colors and this is to be printed out by a printer. In accordance with a predetermined arithmetic expression as shown in the conventional example, the whole image is Y, which is a reference color signal for printing out.
(Yellow), M (magenta), C (cyan), and K (black) and print out.

However, in the image shown in FIG. 10, there are a plurality of regions having different attributes, such as a portion represented by black characters such as 122 and a photograph portion of continuous tone such as 123. Attempts to convert the areas having different attributes using the same arithmetic expression will cause the following inconveniences, for example.

It is desired to reproduce black character portions with a single color of K ink without printing Y, M, and C inks, whereas black portions of a photo portion have a lack of absolute density with a single color of K ink, and the depth of a photo is limited. I want to print using all Y, M, C, and K inks because they will be damaged.

In the photographic part, rich tone reproducibility and color reproducibility are emphasized, while in the character part, high contrast and clear reproduction are required, and the color reproducibility is not important.

The present invention has been made in view of the above points, and has as its object to perform image processing according to the attributes of an input image using a lookup table in a small memory area.

It is another object of the present invention to automatically perform high-precision image processing according to the attributes of an input image.

[0015]

According to a first aspect of the present invention, there is provided an image processing apparatus for performing image processing on input image data using a table to generate output image data. Storing means for storing a plurality of tables corresponding to different attributes;
Extraction means for extracting grid point data by referring to the table based on the bits, and generating means for generating output image data by performing interpolation processing based on the lower M bits of the input image data and the grid point data. The storage means stores a plurality of tables having different values of the N bits referring to the tables.

Further, the second invention of the present application is a storage means for storing N tables having different color processing characteristics, a determination means for determining an attribute of an input image, and the plurality of tables based on the determined attribute. M (M <N) tables are selected from the tables and weighting processing is performed on the data that has been color-processed by the selected M tables according to the determined attribute to generate an output signal. Means.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a block diagram showing an example of a circuit configuration embodying the present invention.

First, a description will be given assuming that 8-bit signal values X, Y, and Z are input as three-color color separation signals. Each color signal has three color signal processing blocks 12-1 to 12-.
3 are input in parallel. Color signal processing block 12-1
Reference numeral 12-3 denotes a processing block for performing well-known color signal processing using a three-dimensional look-up table shown in the conventional example, and output signals C1, C2,
Output C3. Details of the color signal processing block will be described later. C1, C2, and C3 are once input to 14 interpolation circuits.

The CPU 16 reads conversion parameters required for conversion from a storage device (not shown) and sets them in the color processing blocks 12-1 to 12-3.

Next, W is input as a fourth input signal. The three input signals X, Y, and Z are provided as input signals to the color signal processing blocks 12-1 to 12-3 as described above, and output signals C1 to C3 are output, respectively. On the other hand, the fourth input signal W is input to the interpolation circuit 14. The interpolation circuit 14 outputs the three output signals from the 12 and the fourth
And performs an interpolation operation using the input signal W to generate one output signal CS (15).

The above operation will be specifically described by taking a color copying machine as an example.

FIG. 2 shows an outline view of a color copying machine. In FIG. 2, reference numeral 201 denotes an image scanner unit which reads a document and performs digital signal processing. Reference numeral 202 denotes a printer unit which prints out an image corresponding to the document image read by the image scanner 201 on a sheet in full color.

In the image scanner 201, 20
Reference numeral 0 denotes a mirror pressure plate, and a platen glass (hereinafter, platen) 2
The original 204 on the original 03 is illuminated by a lamp 205, guided to mirrors 206, 207, and 208, and three-line solid-state image sensor (hereinafter referred to as CCD) 2
An image is formed on the image 10, and three image signals of red (R), green (G), and blue (B) as full-color information are sent to the signal processing unit 211. Note that 205, 20
Reference numeral 6 denotes a speed v, and 207 and 208 scan the entire original surface (sub-scan) by mechanically moving the line sensor at a speed of 1/2 v in the direction perpendicular to the electrical scanning (main scanning) direction of the line sensor.
I do. Here, the document 204 is read at a resolution of 400 dpi (dots / inch) in both the main scanning and the sub-scanning.

The signal processing unit 211 electrically processes the read image signal, decomposes it into magenta (M), cyan (C), yellow (H), and black (Bk) components. Send to 202. Further, M, C, Y,
One component of Bk is sent to the printer unit 202,
A total of four document scans complete one printout.

Each of the M, C, Y, and Bk image signals sent from the image scanner unit 201 is sent to a laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the sent image signal. The laser light is applied to the polygon mirror 214, f
The photosensitive drum 2 via the −θ lens 215 and the mirror 216
17 is scanned. Here, similarly to the reading, both the main scanning and the sub scanning are written at a resolution of 400 dpi (dots / inch).

Reference numeral 218 denotes a rotary developing unit, which includes a magenta developing unit 219, a cyan developing unit 220, a yellow developing unit 221,
The developing unit includes a black developing unit 222. The four developing units alternately contact the photosensitive drum 217, and develop the electrostatic development formed on the photosensitive drum with toner.

Reference numeral 223 denotes a transfer drum, which winds a sheet supplied from the sheet cassette 224 or 225 around the transfer drum 223, and transfers the developed image on the photosensitive drum to a gist.

After the four colors of M, C, Y, and Bk are sequentially transferred in this manner, the sheet passes through the fixing unit 226, and is discharged after the toner is fixed on the sheet.

FIG. 3 shows the details of the signal processing section 211. C
The R, G, and B signals 301 read by the CD are converted into digital signals by an A / D conversion circuit 302, respectively.
The shading correction circuit described above corrects unevenness in the amount of light of the original illumination lamp and variation in sensitivity of the CCD. A color signal processing circuit 304 is a conversion circuit that converts the input color separation signal described with reference to FIG. 1 into an output color separation signal. The input signals X, Y, and Z correspond to the R, G, and B signals from the shading correction circuit, respectively. Reference numeral 305 denotes an image attribute determining unit that receives the color separation signals X, Y, and Z after the shading correction and determines an image attribute to generate a determination signal W.

Using these X, Y, Z, and W, the color signal processing circuit 304 outputs one output signal 3 as shown in FIG.
07 is generated. Here, C sent to the printer unit
Although a (cyan) signal is shown to be generated, the same procedure is performed for all of M, C, Y, and K, and the signal is transmitted to the printer unit in synchronization with the operation of the printer. CPU306
Sets appropriate parameters in the color signal processing block according to which of M, C, Y, and K signals is to be output.

Next, the operations of the image attribute discriminating unit 305 and the color signal processing unit 304 will be described in detail. Considering the case where a plurality of image attribute areas are mixed in the original as described with reference to FIG. 10, the photographic area 123 is a silver halide photographic original such that the black character area 122 is reproduced only with black toner. It is desirable to perform conversion from R, G, B to M, C, Y, K so as to reproduce colors as faithfully as possible.

The following method is conceivable for realizing this. That is, the character region is composed of a line drawing portion and a solid portion of a single density, while the photographic region has a complex shape with many density levels. Accordingly, when a histogram (occurrence frequency distribution with respect to pixel density) is obtained in a range of about 5 × 5 pixels around the pixel of interest in each area, for a character area as shown in FIG. 4, a specific area as shown in FIG. In the photographic area, the frequency distribution is distributed over a wide range of density levels, as shown in FIG. 4B.

Therefore, the image attribute discriminating unit 305 stores one of the input image signals (for example, a G signal) in 5 × 5 pixels around the pixel of interest and creates a histogram H (i). Here, i is the stored density level (image signal value) of each pixel, and H represents the frequency of appearance. When the frequency distribution is coefficiented for all 5 × 5 pixels, an attribute determination signal W is generated by the following equation (1).

W = {(H (i) / 25) ² } (1) where Σ represents the sum of i (= image signal value) from 0 to 255. Since H (i) represents the frequency of appearance of 5 × 5 pixels, the maximum value of H is 25, for example, when the density values of all the pixels are composed of only one level. That is, in this case, W = 1.

On the other hand, when the pixel values are dispersed in a plurality of density levels as in a photographic area, H (i) becomes considerably smaller than 25, and W becomes relatively small and approaches zero.

As described above, W is close to 1 in the character area, and a value close to 0 is output in the photographic area. Of course, since W is a digital signal, a value between 0 and 1 is represented as an appropriate quantization level, and 8 bits are represented as 0 to 255.

Next, the color signal processing blocks 12-1 to 12-
The configuration of No. 3 and parameters to be set will be described.

First, FIG. 5 shows a configuration example for each block.
The corresponding portions of the color signal processing blocks 12-1 to 12-3 are indicated by dotted frames in FIG. Input X,
The Y and Z signal color signal processing blocks are input in parallel to blocks 12-1 to 12-3. Color signal processing block 12
-1 will be described.
In 2-1 the upper bit signals Ru1, Gu1, and Bu1 of each color
(53-1) and lower bit signals RL1, GL1, BL1
(54-1). Here, the number of bits of the upper bit signal is N1 bits, and the number of bits of the input signal is 8 for each color.
If it is a bit, the number of lower bits is (8-N1) bits.

The upper bit signal is a look-up table L
The output signal value (57-1) input as the address signal of the UT1 (55-1) and stored in the table corresponding to the upper bit signal is read. On the other hand, the lower bit signal is input to the weight coefficient generation circuit 1 (56-1) to generate a weight coefficient 58-1 for the interpolation operation.

The product-sum operation circuit 1 (59-1) performs a well-known product-sum operation using the output signal value 57-1 and the weight coefficient 58-1 to generate a first output signal C1.

The operation of the product-sum operation circuit will be described with reference to FIG. Here, it is assumed that the input signal is two-dimensional R and G for exclamation. The relationship between the input R and G signals is represented by a rectangle on a two-dimensional plane in the drawing, and each of R and G has an 8-bit numerical value of 0 to 255. The look-up table stores output signal values for discrete input signal sets indicated by circles in the figure. The position of this circle is called a lattice point. Number Q of grid points and spacing Δd between grid points
Is determined by the number N1 of upper bits, and Q = (2 ^N1 ) ² Δd = 2 ^(8−N1) . In the figure, the case where N1 = 2 is shown, so that Q =
16, Δd = 32.

First, data of four lattice points (black circles in the figure) determined by upper bit signals Ru and Gu for arbitrary input signals R and G (marks in the figure) are read from LUT1. This is the nearest grid point surrounding the input signal as is apparent from the figure. These data are stored in C00, C10, C01,
C11. Next, a weight coefficient for the product-sum operation is generated from the lower bit signals RL and GL. This is equivalent to obtaining an interpolation coefficient to be obtained by linear interpolation from grid point data in the vicinity of 4 of the output signal with respect to the input signal indicated by x. The weighting factor is a total of 4 for each of the four grid point data.
Required. These are A00, A10, A01, A1
If it is set to 1, it can be obtained by the following equation.

A00 = (Δd-RL) × (Δd-GL) A10 = RL × (Δd-GL) A01 = (Δd-RL) × GL A11 = RL × GL Product-sum operation by the coefficient obtained by this equation Circuit 1 (5
9-1) performs an operation of the following equation to generate an output signal C1.

C1 = (A00 × C00 + A10 × C10
+ A01 × C01 + A11 × C11) / (Δd ² ) The calculation method for the two-dimensional input signal has been described above.
Since it is well known to extend this to three dimensions, the description is omitted here. However, the number Q of grid points related to the capacity of the lookup table and the grid point interval Δ that affects the accuracy of the output signal are described.
The relation of d is as follows in the case of a three-dimensional input signal.

Q = (2 ^N1 ) ³ Δd = 2 ^{(8−N1) In other} words, as the value of N1 is increased, Δd decreases and the interval between the lattice points in FIG. 6 becomes dense. The accuracy of is improved. However, when the value of Q is increased by 1 (bit) N1 only, the value of Q becomes 8 times, and the memory cost increases accordingly.

Therefore, in the fifth embodiment, in the three color signal processing blocks having the same structure shown in FIG.
2 and N3 are configured to be different.

The configuration method will be described below.

As described above, in the character area, the input R, G,
It is desirable that the color of the B signal which is close to R = G = B = 0, that is, the color represented by black, is replaced with a signal of only K with C = M = Y = 0. Such grid point data is set in the color signal processing block 12-3. In general, the color reproduction of a character image does not need to be very faithful to the original, and the conversion accuracy of the color signal processing does not need to be very high. Therefore, the number of grid points in the LUT 3 for storing output signals does not need to be very large. That is, the value of N3 can be reduced, and the memory capacity can be saved.

In the photographic area, it is desirable to obtain color reproduction as close as possible to that of the input document, and it is necessary to convert the signal into an output signal that reproduces the document as faithfully as possible. Generally, it is necessary to perform non-linear conversion in order to obtain an output signal capable of obtaining high color reproducibility with respect to an input signal, and the conversion accuracy improves as the number of lattice points of the LUT increases. For example, when a black signal of R = G = B = 0 is input, it is desirable from the viewpoint of color reproducibility that conversion is performed so that four colors such as C = M = Y = 100 and K = 255 are simultaneously printed. Therefore, grid point data corresponding to such non-linear conversion is set in the color signal processing block 12-1, and a large value is set in N1 to reduce the grid point interval.

In the color signal processing block 12-2, intermediate grid point data between the two is set with an intermediate bit number N2.

As a normally conceivable configuration, it is desirable to use numerical values such as N1 = 4 bits, N2 = 3 bits, and N3 = 2 bits.

In the above, the number of input bits N1, N2, and N3 of each look-up table are determined in advance in the circuit configuration, and the grid point data of the number of grid points is determined by CP.
Set from U16.

With this configuration, different output signals C for the same R, G, B input signals (X, Y, Z in the figure)
1 to C3 are obtained. For these values, the interpolation circuit 14 in FIG. 1 performs the following calculation based on the above-described image attribute discrimination signal W to obtain a final output signal CS.

When 0≤W <85 CS = C1 + (C2-C1) * W / 85 When 85≤W <170 CS = C2 + (C3-C2) * (W-85) / 85 170≤W <255 CS = C2 + (C3-C2) * (W-170) / 85

That is, when W = 0, a value close to the output signal C1 calculated by the parameters of the color signal processing block 12-1 is output as CS. This is an output signal suitable for a photographic area.

When W = 1, the output signal C calculated by the parameters of the color signal processing block 12-3 is used.
A value close to 3 is output as CS, which is an output signal suitable for the character area.

When W is an intermediate value between 0 and 1,
An intermediate value between the output signal suitable for the photographic area and the output signal suitable for the character area is generated by interpolation with the value of W.

According to this embodiment, the conversion according to the attribute of the input image portion can be automatically performed using the look-up table.

By changing the value of N, the value of N is increased in the photographic area to perform conversion excellent in gradation reproducibility and color reproducibility, and conversely, by reducing N in the character area, the color is reduced. Although the reproducibility is somewhat sacrificed, the memory capacity can be greatly reduced.

(Second Embodiment) FIG. 7 is a block diagram showing a color signal processing circuit according to a second embodiment.

Here, two color signal processing blocks (72
-1, 72-2) and the two output signals C1 and C2 are set to 74
Is configured to be selected by the selector. The image area discrimination signal W ′ is a 1-bit signal, which is obtained by binarizing the value of W obtained by Expression (1) in the first embodiment with a predetermined threshold value. For example, it is obtained such that W ′ = 1 when W> 128 and W ′ = 0 when W <127.

72-1 and 72-2 are similarly configured using the bit numbers N1, N3 and grid point data set in the color signal processing blocks 12-1 and 12-3 in the first embodiment.

The selector 74 selects one of C1 and C2 according to W 'and sets it as an output signal CS. Obviously W '
When = 0, the output signal C1 for the photograph area is selected and CS is selected.
When W '= 1, the output signal C2 for the character area is selected and output as CS.

By doing so, the same effect as in the above embodiment can be obtained.

(Third Embodiment) FIG. 8 is a block diagram showing a configuration of a color signal processing circuit according to a third embodiment. The other circuit configuration is the same as that of the first embodiment.

In the third embodiment, the color signal processing block is set to N
I am prepared.

Hereinafter, the configuration of the color signal processing circuit of the third embodiment will be described assuming that 8-bit signal values X, Y, and Z are input as three-color color separation signals. Each color signal is input in parallel to N color signal processing blocks 80-1 to 80-N. The color signal processing blocks 80-1 to 80-N are processing blocks for performing color signal processing.
The output signals C1, C2,..., CN for Y and Z are output. C1 to CN are temporarily input to the interpolation circuit 81.

The CPU 82 reads a conversion parameter required for conversion from a storage device (not shown) and sets it in the color signal processing blocks 80-1 to 80-N.

Next, W is input as a fourth input signal. The fourth input signal W is input to the interpolation circuit 81. The interpolation circuit 81 performs an interpolation operation using the N output signals from the color signal processing block and the fourth input signal W to generate one output signal CS, as described later.

Next, the operations of the image attribute determining section and the color signal processing section will be described in detail.

First, an example of a document image will be described with reference to FIG.

The image 131 shown in FIG. 12 has different portions such as a portion represented by black characters such as 132, a graph portion divided into a plurality of colors such as 133, and a continuous tone photograph portion such as 134. There are multiple areas with attributes.

It is desired to reproduce the black character portion 122 with a single color of the K ink without printing the Y, M, and C inks. Photo part 12
In the black portion of 4, the K ink single color lacks the absolute density and the depth of the photograph is impaired, so it is desired to print using all the Y, M, C, and K inks. Since the graph portion 123 is colored with vivid colors, it is desirable to reproduce colors with as high a saturation as possible without mixing C, M, and Y as much as possible.

Considering the case where a plurality of image attribute areas are mixed in a document as described with reference to FIG. 12, the graph area 133 is changed so that the black character area 132 is reproduced only with black toner. In order to reproduce colors as vividly as possible by emphasizing colors, and from R, G, B to M, C, Y, K so as to reproduce colors as faithfully as possible in silver halide photographic originals.
It is desirable to convert to

The following method is conceivable for realizing this. That is, the character area and the graph area are composed of a line drawing portion and a solid portion of a single density, while the photographic region has a complex shape with many density levels. Accordingly, when a histogram (occurrence frequency distribution with respect to pixel density) in a range of about 5 × 5 pixels around the target pixel is obtained for each area, for example, as shown in FIG. In the photographic area, the frequency distribution is distributed over a wide range of density levels, as shown in FIG. 4B.

At the bottom, the image attribute discriminating unit 305 stores one of the input image signals (for example, the Y signal) as 5 × 5 pixels around the pixel of interest and creates a histogram H (i). Here, i is the stored density level (image signal value) of each pixel, and H represents the frequency of appearance. The frequency distribution is coefficientd for all 5 × 5 pixels, and the attribute determination signal W is generated by the above equation (1).

Therefore, as shown in FIG. 4A, a character whose frequency is concentrated at a specific density level, W is 1 in the graph area.
Become closer to

On the other hand, when the pixel values are dispersed in a plurality of density levels as in a photographic area, H (i) becomes considerably smaller than 25, and W becomes relatively small and approaches zero.

As described above, W is close to 1 in the text and graph areas, and a value close to 0 in the photographic area. Of course, since W is a digital signal, a value between 0 and 1 is represented as an appropriate quantization level, and 8 bits are represented as 0 to 255.

Next, parameters to be set in the color signal processing blocks 80-1 to 80-N will be described. As described above, it is desirable to convert the input R, G, and B signals into color signals that are as close as possible to the primary colors of Y, M, C, and K in the character and graph regions. That is, a color close to R = G = B = 0, that is, a color represented by black is replaced with a signal of only K at C = M = Y = 0, and a red color such as R = 255, G = 0, B = 0. It is desirable to replace the colors represented by signal values of only Y and M (C = K = 0). Such conversion parameters are set in the color signal processing block 80-N.

In the photographic area, it is desirable to obtain color reproduction as close as possible to the input signal. For example, when a black signal of R = G = B = 0 is input, C
= M = Y = 100 and K = 255. Such conversion parameters are set in the color signal processing block 80-1.

The color signal processing blocks 80-2 to 80- (N
In -1), an intermediate parameter between the two is set.

The above parameters are set from the CPU.

With this configuration, different output signals C for the same R, G, B input signals (X, Y, Z in the figure)
1 to CN are obtained. The interpolation circuit 14
Performs the following calculation based on the above-described image attribute determination signal W to obtain a final output signal CS. Here, a case where N = 5 will be described.

When 0≤W <64 CS = C1 + (C2-C1) * W / 64 When 64≤W <128 CS = C2 + (C3-C2) * (W-64) / 64 128≤W <192 In the case of CS = C3 + (C4-C3) * (W−128) / 64 When 192 ≦ W <255 CS = C4 + (C5-C4) * (W−192) / 63

That is, when W = 0, the value close to the output signal C1 calculated by the parameter 12-1 is C
Output as S. This is an output signal suitable for a photographic area.

When W is close to 1, a value close to the output signal C5 calculated by the parameter 12-5 is output as CS, which is an output signal suitable for a character and a graph area.

When W is an intermediate value between 0 and 1,
An intermediate value between the output signal suitable for the photographic area and the output signal suitable for the text and graph areas is generated by interpolation with the value of W.

It should be noted that M (N
> M) for the output signal from the color signal processing block,
Interpolation processing may be performed to obtain a final output signal.

(Other Embodiments) In the present invention, it is of course possible to adopt a configuration in which the parameters for color signal conversion in each of the above embodiments are downloaded from a host computer.

In each of the above embodiments, only one output signal suitable for each discriminated area is output. However, for example, a device that can simultaneously print M, C, Y, and K is used as a printer unit. In the case, 4 of M, C, Y, K
It may be configured to output three different signals in parallel.

Further, the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.) or to an apparatus including one device (for example, a copying machine or a facsimile machine). Good.

Further, software for realizing the functions of the above-described embodiment is provided in an apparatus or a computer in the system connected to the various devices so as to operate the various devices so as to realize the functions of the above-described embodiment. The present invention also includes a program code supplied and executed by operating the various devices according to a stored program in a computer (CPU or MPU) of the system or apparatus.

In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, such as the program code The storage medium storing the information constitutes the present invention.

As a storage medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, nonvolatile memory card, ROM or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer, or another program. Needless to say, the program code is included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with application software or the like.

Further, the supplied program code is stored in a memory provided in a function expansion board of the computer or a function expansion unit connected to the computer, and then stored in the function expansion board or the function storage unit based on the instruction of the program code. It is needless to say that the present invention includes a case where a provided CPU or the like performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0098]

As described above, according to the present invention,
Image processing according to the attributes of input image data can be performed using a look-up table in a small memory area.

Further, high-precision image processing according to the attributes of the input image can be automatically performed.

[Brief description of the drawings]

FIG. 1 illustrates a configuration of a color signal processing circuit according to a first embodiment.
FIG. 4 is a block diagram showing an example.

FIG. 2 is an outline view of the color copying apparatus according to the first embodiment.

FIG. 3 is a block diagram showing an example of a configuration of a signal processing unit according to the first embodiment.

FIG. 4 is an exemplary view for explaining the principle of image attribute determination according to the first embodiment;

FIG. 5 is a block diagram showing an example of a configuration of a color signal processing block according to the first embodiment.

FIG. 6 is a view for explaining the principle of color signal processing using a lookup table.

FIG. 7 shows a first configuration of the color signal processing circuit according to the second embodiment.
FIG. 4 is a block diagram showing an example.

FIG. 8 shows a configuration of a color signal processing circuit according to a second embodiment.
FIG. 4 is a block diagram showing an example.

FIG. 9 is a diagram illustrating a conventional color signal conversion method.

FIG. 10 is a diagram illustrating a conventional table conversion method.

FIG. 11 is a diagram showing an example of a document image.

FIG. 12 is a diagram showing an example of a document image.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/46 Z

Claims (11)

[Claims] 1. An image processing apparatus for performing image processing on input image data using a table to generate output image data, comprising: storage means for storing a plurality of tables corresponding to different attributes; Extracting means for extracting grid point data by referring to a table based on the upper N bits of the data, and generating means for generating output image data by performing an interpolation process based on the lower M bits of input image data and the grid point data The image processing apparatus according to claim 1, wherein the storage unit stores a plurality of tables having different values of the upper N bits referring to the tables. 2. An input means for inputting attribute information indicating an attribute of the input image data; and a weighting process for output image data generated by a plurality of tables corresponding to the different attributes based on the attribute information. 2. The image processing apparatus according to claim 1, further comprising a weighting processing unit that performs the following. 3. The image processing apparatus according to claim 2, further comprising a determination unit configured to determine an attribute of the input image data based on image data corresponding to a plurality of pixels including the input image data and generate the attribute information. The image processing apparatus according to any one of the preceding claims. 4. The plurality of tables stored in the storage means include a first table corresponding to a photographic image and a second table corresponding to a character image. 2. The image processing device according to 1. 5. The image processing apparatus according to claim 3, wherein the value of the upper N bits is larger in the first table than in the second table. 6. The image processing apparatus according to claim 4, wherein the second table has grid point data such that an achromatic color is reproduced as a single black color. 7. An image processing method for performing image processing on input image data based on a plurality of stored tables corresponding to different attributes to generate output image data, comprising: An extraction step of extracting grid point data by referring to a table based on the table, and a generation step of generating output image data by performing an interpolation process based on lower M bits of input image data and the grid point data, The image processing method according to claim 1, wherein the stored table differs in the value of the upper N bits referring to the table. 8. A storage unit for storing N tables having different color processing characteristics; a determination unit for determining an attribute of an input image; and M (M <M) based on the determined attribute. Means for selecting N) tables and performing weighting processing on the data color-processed by the selected M tables in accordance with the determined attribute to generate an output signal. Image processing apparatus. 9. The image processing apparatus according to claim 8, wherein the determination unit detects a distribution of several pixels including an attribute determination pixel and determines an attribute of the input image. 10. The image processing apparatus according to claim 8, wherein said determining means determines an attribute for each pixel. 11. An attribute of an input image is determined to generate attribute information, and M (M <N) tables are selected from N tables having different stored color processing characteristics based on the attribute information. An image processing method comprising: performing weighting processing according to the determined attribute on data color-processed by the selected M tables to generate an output signal.