JP2003333348A - Apparatus and method for extending color signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color signal extending apparatus for suppressing occurrence of false contour. <P>SOLUTION: A color signal extending apparatus 1 is provided with: an input port 101; a color signal processing section 102, a display apparatus 103; a line memory 11; a memory control section 12; and a color signal extending section 13. The color signal extending section 13 is provided with: a data distribution detection section 14; and a data depth extending section 15. The color signal processing section 102 processes color signal data received by the input port 101, and the memory control section 12 writes the processed data to the line memory 11. The data distribution detection section 14 detects the distribution state of the color signal data stored in the line memory 11 and decides an additional value attached to the data value on the basis of the distribution state. The data depth extending section 15 attaches the decided additional value to the data value to extend the color signal data. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal extending device and method, and more particularly to a technique for extending the data depth of a color signal of image data.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a configuration of a conventional color signal extending apparatus 100. The color signal expansion device 100 includes an input port 101, a color signal processing unit 102, and a display device 10.
Equipped with 3.

Next, the operation will be described with reference to FIG. To the color signal expansion device 100, RGB (red, green, blue) color signals that have been quantized in the preceding stage and become digital signals are input from the input port 101. The input color signal is arithmetically processed by the color signal processing unit 102, transferred to the display device 103, and displayed as an image.

The color signal processing unit 102 performs predetermined image data processing such as image adjustment and processing by addition and integration on each color signal. Further, a process of expanding the bit depth of data according to the display capability of the display device 103 is performed. The color signal processing unit 102 may be realized by either hardware or software.

The image data processing performed in the preceding stage of the color signal expansion device 100 or in the color signal processing unit 102 is generally performed in bit units of multiples of 8 in order to reduce the hardware scale and memory capacity. Is. For example,
R: G: B = 3: 3: 2 bits (total 8 bits) or R: G: B = 5: 6: 5 bits (total 16 bits), etc. The bit length is being shortened.

Here, the bit length is R: G: B = 5:
An example will be described in which data shortened to 6: 5 bits (a color signal in which information is reduced by 1 bit for each color signal of R and B) is input from the input port 101. The display device 103 has a capability of displaying more gray scales than color signals input from the input port 101, and has a display capability of, for example, R: G: B = 6: 6: 6 bits. And

Since the display device 103 corresponds to 6 bits for each of RGB, the color signal processing unit 102 performs the predetermined image data processing and then the bit depth of the data for the R and B color signals. It is necessary to generate extended image data that is obtained by extending and transfer it to the display device 103. Conventionally, in such extension processing, a technique has been proposed in which extension image data is generated by adding an additional value “0” to the lower order for each color signal of R and B.

FIG. 8 is a diagram illustrating data values of R (red) in pixels (X0 to X5) arranged in the horizontal direction in the image data. Further, FIG. 9 is a diagram showing a data value of R (red) after the pixel shown in FIG. 8 has undergone expansion processing by a conventional method.

Input port 101 of color signal expansion apparatus 100
As described above, the lower one bit is reduced and the image data (color signal) whose bit length is shortened is input to the. Then, since the color signal processing unit 102 expands the bit depth of the data by uniformly adding “0” to the image data, for example, originally the data value is “1” =
The data value of the pixel X1 that was 000001 becomes “0” = 00000 at the stage of converting to 5 bits, and after the predetermined image processing, the color signal processing unit 102 adds “0” to the least significant digit of this bit string to 0 ”= 000000.

[0010]

However, when the color signal subjected to the above-described expansion processing is displayed on the display device 103, the pixels X0 and X1 are displayed in the same color as the red component, which is indicated by the dotted line in FIG. As shown, the original color difference is lost. On the other hand, the pixels X1 and X2 are displayed in a color in which the difference between the data values of the red component is “2”,
As shown by the thick line in FIG. 9, the color difference between pixels is emphasized. Therefore, when a person looks at such an image, a pseudo contour (a portion between the pixels X1 and X2, or a portion between the pixels X3 and X4) in which the color difference between the pixels is emphasized ( Hereinafter, it is felt that there is a "pseudo contour".

That is, in the conventional color signal expansion device, when an image is displayed using a display device capable of displaying color signals of more gradations in a situation where the information amount of the color signal is reduced, it is uniformly applied. Since the additional value "0" is added to the lower bits to deal with the problem, there is a problem that the pseudo contour is easily noticeable.

The present invention has been made in order to solve the above problems, and suppresses the occurrence of pseudo contours even when the image data in which the information of a predetermined color is reduced is expanded. The purpose is to obtain color signal extension technology.

[0013]

In order to solve the above-mentioned problems, the invention of claim 1 is an apparatus for expanding a color signal, wherein a distribution state of data values of the color signal in a spatial pixel array is set. Based on the additional value determining means for determining an additional value to be added to the data value of the color signal, and an extension in which the data depth of the color signal is extended while giving a value according to the additional value to the extension portion. And expansion means for generating color signals.

According to a second aspect of the present invention, in the color signal extending apparatus according to the first aspect of the present invention, the additional value determining means is spatially continuous with the data value of the color signal being substantially constant. Pixel block detection means for detecting a pixel block as a group of pixels, and the additional value according to the change state of the data value of the color signal in each of the pixel adjacent to the pixel block and the pixel included in the pixel block. Adjacent pixel determining means for determining

According to a third aspect of the present invention, in the color signal extending apparatus according to the second aspect of the present invention, the pixel block detecting means has the number of pixels included in the group of pixels within a predetermined range. Only certain ones are detected as the pixel block.

According to a fourth aspect of the present invention, in the color signal extending apparatus according to the third aspect of the present invention, the pixel block detecting means sets the number of pixels included in the pixel group to a predetermined lower threshold value or less. The larger one is detected as the pixel block.

A fifth aspect of the present invention is the color signal extending apparatus according to the third or fourth aspect of the present invention, wherein the pixel block detecting means sets the number of pixels included in the pixel group to a predetermined upper limit. Those smaller than the threshold are detected as the pixel block.

A sixth aspect of the present invention is the color signal expansion apparatus according to any one of the first to fifth aspects of the present invention, further comprising storage means for storing one line of the color signal. The additional value determination means determines the additional value based on the distribution state of the data values in the color signals for one line in the storage means, and the expansion means for the one line stored in the storage means. The time-division processing for sequentially generating the extended color signal is performed for each of the color signals.

The invention of claim 7 is the color signal expanding apparatus according to any one of claims 1 to 6, wherein a plurality of color component signals in the full-color image signal are expanded as the color signals. And the extended color signal is generated independently for each color component signal.

An eighth aspect of the present invention is the color signal extension apparatus according to any one of the first to seventh aspects of the present invention, wherein the extension of the color signal is addition of M bits (M is an integer of 2 or more). And the additional value is selected by allowing any of the M powers of 2 that can be represented by the M bits.

A ninth aspect of the present invention is a method for expanding a color signal, which is added to the data value of the color signal based on the distribution state of the data value of the color signal in the spatial pixel array. An additional value determining step for determining an additional value for the above, and an extending step for generating an extended color signal in which the data depth of the color signal is extended while giving a value according to the additional value to the extended portion.

According to a tenth aspect of the invention, there is provided the color signal expansion method according to the ninth aspect, wherein the additional value determining step is spatially continuous with the data value of the color signal being substantially constant. A pixel block detecting step of detecting a pixel block as a group of pixels, and the additional value according to the change state of the data value of the color signal in each of the pixel adjacent to the pixel block and the pixel included in the pixel block. And an adjacent pixel determining step for determining.

The invention of claim 11 is the color signal extending method according to the invention of claim 10, wherein in the pixel block detecting step, the number of pixels included in the group of pixels is within a predetermined range. Only certain ones are detected as the pixel block.

According to a twelfth aspect of the present invention, in the color signal extending method according to the eleventh aspect of the present invention, in the pixel block detecting step, the number of pixels included in the pixel group is less than a predetermined lower threshold value. The larger one is detected as the pixel block.

The thirteenth aspect of the present invention is the color signal extending method according to the eleventh or twelfth aspect of the present invention, wherein in the pixel block detecting step, the number of pixels included in the pixel group is a predetermined upper limit. Those smaller than the threshold are detected as the pixel block.

The invention of claim 14 is the color signal expanding method according to any one of claims 9 to 13, further comprising a storage step of storing one line of the color signal, wherein the addition The value determining step determines the additional value based on the distribution state of the data values in the color signal for one line stored in the storing step, and the expanding step determines the additional value for one line stored in the storing step. The time-division processing for sequentially generating the extended color signal is performed for each of the color signals.

The invention of claim 15 is the color signal expanding method according to any one of claims 9 to 14, wherein a plurality of color component signals in the full-color image signal are expanded as the color signals. And the extended color signal is generated independently for each color component signal.

The invention of claim 16 is the color signal expansion method according to any one of claims 9 to 15, wherein the expansion of the color signal is M bits (M is an integer of 2 or more).
Is added, and the additional value is selected by allowing any of the 2 M power values that can be represented by the M bits.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to the drawings showing the embodiments thereof.

Embodiment 1. FIG. 1 is a block diagram of a color signal expansion device 1 according to the first embodiment of the present invention. The color signal expansion device 1 includes a line memory 11, a memory control unit 12, and a color signal expansion unit 13. It should be noted that configurations having the same functions as those of the conventional color signal expansion device 100 will be described with the same reference numerals as appropriate. However,
The color signal processing unit 102 of the color signal expansion device 1 performs only predetermined image data processing, and does not perform color signal expansion processing.
Further, the display device 103 uses a display device capable of displaying gray scales of R: G: B = 6: 6: 6 bits.

The line memory 11 has a length of one line (hereinafter simply referred to as "one line") of a spatial pixel array (horizontal or vertical direction) of an image to be processed, and color signal expansion processing. It has the same bit width as the subsequent bit depth, that is, the bit depth of the color signal data corresponding to the number of gradations of the display device 103, and the image data output from the color signal processing unit 102 and the display device 103. It has a function of temporarily storing image data (extended image data) and the like to be output to.

As described above, by using the line memory 11 for storing the data for one line of the expanded image data, the memory capacity required for the expansion processing of the data depth can be minimized, and thus the color signal The configuration of the expansion device 1 can be simplified, and the price can be reduced. Note that a larger capacity memory may be used to execute the expansion process. In that case, since sufficient memory can be used, it is not necessary to perform complicated processing (time-division processing or the like), and the control operation can be simplified.

The memory controller 12 controls reading and writing of various data from and to the line memory 11.

The color signal expansion unit 13 includes a data distribution detection unit 1
4 and a data depth extension unit 15.

The data distribution detecting section 14 is provided in the line memory 1
1 has a function of determining an additional value to be added to the data value of the predetermined color signal based on the distribution state of the data value of the predetermined color signal in the color signal data held by 1.
That is, the data distribution detecting unit 14 mainly corresponds to the additional value determining means in the present invention.

Further, the data distribution detecting unit 14 has a function of detecting a pixel block as a group of pixels in which the data value of the color signal is substantially constant and is spatially continuous, and the pixel adjacent to the pixel block and the pixel block concerned. And a function of determining the above-mentioned additional value in accordance with the change state of the data value of the color signal in each of the pixels included in. Note that these specific methods will be described later.

The data depth extension unit 15 produces extended image data in which the data depth of the color signal data is extended while giving a value according to the additional value determined by the data distribution detection unit 14 to the extension portion. That is, the data depth extension unit 15
It mainly corresponds to the expansion means in the present invention.

The above is the description of the configuration of the color signal expansion device 1 in the present embodiment.

FIG. 2 is a diagram showing an example of data values of R (red) in the original image data. Here, the original image data is data before the data value for a predetermined color signal is reduced. In FIG. 2, the horizontal axis represents the position X of each pixel in the color signal data for one line. The vertical axis represents the R data value of each pixel. As shown in FIG. 2, since 1-bit reduction processing has not been performed on the original image data,
R is also represented by 6 bits. Note that X is
It is a natural number from “0” to “n (n is the number of pixels for one line)”. Further, ranges A to F indicate ranges in which data values are characteristically distributed, and details will be described in FIG.

FIG. 3 is a diagram showing a data value when the data value of the color signal data shown in FIG. 2 is reduced to 1 bit by 5 bits. In FIG. 4, by adding “0” to the color signal data shown in FIG.
It is a figure which shows the data value at the time of expanding the data depth of color signal data.

Ranges A to F are, in a state where the data value is reduced (state shown in FIG. 3), Range A: a range in which the data value gradually increases, and Range B: a data value changes abruptly. Range, range C: range in which the data value gently decreases, range D: range in which the data value is constant between pixels with large data values on both sides, range E: many pixels with the same data value are continuous. The range F is a range in which the data value sandwiched by pixels having small data values on both sides is constant.

As described above, the input port 101 of the color signal expansion apparatus 1 is not the original image data shown in FIG. 2 but the original image data shown in FIG. 3 for the purpose of speeding up the processing in the color signal processing unit 102. The color signal data with the reduced data value for a predetermined color (for example, red) as shown in FIG. When the conventional color signal extending apparatus 100 generates extended image data based on such color signal data and the extended image data is displayed by the display apparatus 103, as shown in FIG.
Pseudo contours occur in portions such as the range A and the range C.

The processing operation for expanding the data depth of the color signal data in the color signal expansion apparatus 1 according to the present embodiment will be described below by taking the case where the color signal data shown in FIG. 3 is input as an example. That is, in the present embodiment,
It is assumed that color signal data of R: G: B = 5: 6: 5 bits is input as image data in which information corresponding to R and B is reduced by 1 bit.

First, when the above-mentioned color signal data is input to the input port 101, the color signal processing unit 102 performs data processing (predetermined image data processing). Next, the color signal data output from the color signal processing unit 102 is written in the line memory 11 for each line under the write control of the memory control unit 12.

When the color signal data for one line is written in the line memory 11, the data distribution detection unit 14 determines the distribution state of the data values of R and B in pixel units for the color signal data for one line. Is detected, and an additional value to be added to the data value is determined based on the distribution state.

Here, the method of detecting the distribution state of the data values of the color signal and the method of determining the additional value by the data distribution detecting unit 14 will be described. As described above, since the pseudo contour occurs in the image portion where the color changes gently, the data distribution detection unit 14 changes from the distribution state of the data values to the distribution state ER where the color changes gently. The pixels that are present are extracted (detected).

First, from the color signal data for one line, R
A pixel group Ki in which the data value of (red) is substantially constant and which is spatially continuous is detected, and the number of pixels Ni included in each pixel group Ki (the minimum number of pixels is 1) is obtained.

Specifically, the R data value of the pixel (X = 0) located at the left end in the color signal data for one line is acquired and set as V0. R data value of each pixel is V to the right
While sequentially acquiring the value of 1, the process is repeated until V0 and V1 have different values.

When V0 and V1 have different values, the pixels up to the pixel (X = k-1) before the pixel (X = k (k = 1 to n)) at that time are regarded as one pixel group K1. And the number of pixels N1 included in the pixel group K1 (N1 = k−
0) is acquired. Further, V1 is newly set as V0, and the same process is repeated from the pixel (X = k) adjacent to the rightmost pixel of the pixel group K1 detected immediately before.

Thus, for example, in the example shown in FIG.
A pixel group Ki (i
= 1 to 14), and the number of pixels Ni included in each pixel group Ki is obtained.

Next, for each pixel group Ki, the number of pixels Ni
By comparing the lower limit threshold value (lower limit pixel number) P and the upper limit threshold value (upper limit pixel number) Q with the pixel number Ni within a predetermined range (greater than or equal to the lower limit threshold P and less than or equal to the upper limit threshold Q). Only Ki is detected as the pixel block Bk. Further, the pixels included in the pixel group Ki that are not classified into the pixel block Bk are classified as pixels in the distribution state ES in which the red color does not change gently.

This is the number of pixels Ni included in the pixel group Ki.
Is less than the predetermined lower limit threshold P, it means that the pixels for which the data value of R is constant are not consecutive in the pixel group, and that red changes gently in this range. Because I can't say. Further, the case where the number of pixels Ni is larger than the predetermined upper limit threshold value Q corresponds to, for example, the case where the red component of the entire screen is substantially constant, and in this case as well, it cannot be said that the red color changes gently. Because.

As described above, in the color signal extending apparatus 1, only the pixel group Ki in which the number of pixels Ni included in the pixel group Ki is within the predetermined range (more than the lower limit threshold P and less than the upper limit threshold Q) By detecting the block Bk, it is possible to detect a pixel whose color changes gently. The lower limit threshold P and the upper limit threshold Q are set as reference values in advance from an arbitrary natural number of n or less, and the lower limit threshold P is a value smaller than the upper limit threshold Q.

As a result, in the example shown in FIG. 3, two pixel groups K1 and K2 included in the range A and 3 included in the range C are included.
One pixel group K8 to K10, one pixel group K11 included in the range D, and one pixel group K13 included in the range F are detected as the pixel block Bk. Further, the pixels included in the pixel group K1 existing before the range A, the pixels included in the four pixel groups K4 to K7 included in the range B (the pixel numbers N4 to N7 are all less than the lower limit threshold P), and the range E are included in the range E. One included pixel group K12 (number of pixels N
Pixels included in (12 is larger than the upper limit threshold Q) and pixels included in the pixel group K14 existing after the range F are classified as pixels in the distribution state ES.

Further, among the adjacent pixels existing before and after each detected pixel block Bk, the R of the previous (left) pixel is
The difference VS is obtained by subtracting the data value of R of the pixel included in the pixel block Bk from the data value of
The difference VE is obtained by subtracting the R data value of the pixel included in the pixel block Bk from the R data value of the pixel of. Then, the pixel block Bk in which the absolute value of either one of the differences VS and VE is equal to or less than the predetermined determination threshold S is
The pixels included in the other pixel blocks Bk are classified as the distribution state ER (the distribution state in which the red color is gently changing), and the pixels included in the distribution state ES.

This is because the absolute values of the obtained differences VS and VE correspond to the change amount (change state) of red color. Therefore, when the absolute value of any one of them is less than or equal to the determination threshold value S, the pixel This is because it can be said that the color changes gently in the block Bk.

As a result, the color signal expansion device 1 determines the pixels in the distribution state ER according to the change state of the data value of the color signal in each of the pixel adjacent to the pixel block Bk and the pixel included in the pixel block Bk. Since it can be detected, the additional value can be determined according to whether or not each pixel is included in the distribution state ER in the process described later. Note that the determination threshold S is set in advance as a positive value of “1” or more.

As a result, in the example shown in FIG. 3, all the pixel blocks Bk are classified into the distribution state ER.

By the processing up to this point, the line memory 11
The color signal data held in the data of the pixels of the distribution state ER (pixels included in the pixel block Bk classified into the distribution state ER) in which the data value of R changes gently, and the other distribution states It is classified into ES pixel data.

Next, the data distribution detecting unit 14 determines the pixel blocks Bk classified into the distribution state ER according to the positive / negative of the obtained differences VS and VE: 1) distribution state ER1 (both differences VS and VE are positive), 2) distribution state ER2 (both difference VS and VE are negative), 3) distribution state ER3 (difference VS is positive, difference VE is negative), 4) distribution state ER4 (difference VS is negative, difference VE is positive) 4 Classify as street distribution.

As a result, in the example shown in FIG. 3, the pixel blocks Bk classified as the distribution state ER (pixel group Ki in which the number of pixels is within a predetermined range) are included in the range A.
One pixel group K2, K3 is in the distribution state ER1 and three pixel groups K8 to K10 included in the range C are in the distribution state ER2.
And one pixel group K13 included in the range F has a distribution state E
R3 and one pixel group K11 included in the range D are classified as the distribution state ER4.

Here, in the distribution state ER3, the distribution of data values is convex upward, and if the pixel blocks Bk classified into the distribution state ER3 are divided into front and rear, the front part (left part) has a gentle red color. Increasing distribution status (distribution status ER1
It can be considered that the rear part (right part) has a distribution state in which the red color is gently reduced (classified as distribution state ER2).

Similarly, in the distribution state ER4, the distribution of the data values is in a downward convex state, and in the front part of the pixel block Bk classified into the distribution state ER4, the red state is gradually reduced (distribution state). ER2), and the rear part can be regarded as a distribution state in which red color is gently reduced (classification into ER1).

Therefore, the pixel blocks Bk classified into the distribution states ER3 and ER4 can be divided into the distribution states ER1 and ER2 by being divided into front and rear, respectively, and as a result, the pixels in the distribution state ER are distributed into the distribution state ER1.
Alternatively, it is classified as one of the pixels of ER2.

Further, the data distribution detection unit 14: 1) Pixel block Bk classified into distribution state ER1 (pixel block B classified into distribution state ER3 or ER4)
In k, the front part or the rear part) is divided into the front part and the rear part, the pixels in the front part are classified as the pixel block Bk11, and the pixels in the rear part are classified as the pixel block Bk12, and are classified into the distribution state ER2. Pixel block Bk (pixel block B classified into distribution state ER3 or ER4
In k, the rear part or the front part) is similarly divided into the front part and the rear part, and the pixels in the front part are classified as the pixel block Bk21 and the pixels in the rear part are classified as the pixel block Bk22.

As a result, the classification (detection of the distribution state) based on the distribution state of the data values of R is completed for all the pixels of one line held in the line memory 11.

Next, the data distribution detector 14 determines an additional value to be added to the R data value of the pixel based on the distribution state detected for each pixel.

That is, the pixels in the distribution state ES (the distribution state in which the red color does not change gently) and the pixel block B
A pixel included in k11 (the front part of the pixel block Bk in the distribution state where the red color is gradually increasing) and a pixel block Bk22 (the rear part of the pixel block Bk in the distribution state where the red color is gradually decreasing). For the R data value of the pixel, the additional value is determined to be “0”.

The pixels included in the pixel block Bk12 (the rear part of the pixel block Bk in the distribution state where the red color is gradually increasing) and the pixel block Bk21 (The pixel block Bk in the distribution state where the red color is gradually decreasing). For the data value of R with the pixel included in (the front part of), the additional value is determined as “1”.

Thus, the data distribution detector 14 can determine the additional value to be added to the data value of the color signal based on the distribution state of the data value of the color signal in the spatial pixel array.

When the data distribution detection unit 14 determines the additional value to be added to the R data value of each pixel, the data depth expansion unit 15 sets the value corresponding to the determined additional value to the R value of each pixel. Data having an expanded data depth of R is generated by adding it to the least significant bit (extended portion) of the data value of.

FIG. 5 is a diagram showing the result of the 1-bit expansion processing of the data value shown in FIG. 3 by the color signal expansion device 1. In the expansion processing by the conventional color signal expansion device 100, as shown in FIG. 4, pseudo contours are generated in the range A and the range C, but when the expansion process is performed by the color signal expansion device 1, As shown in FIG. 5, the change of the data value is gentle and the generation of the pseudo contour is suppressed. Further, it can be seen that the original image data shown in FIG. 2 can be reproduced more faithfully and a more natural image can be reproduced.

When the extension processing of the data value of R is completed, B
Similarly, the extension processing is performed on the data value of 1 to generate extended image data for one line.

As described above, since a plurality of color component signals in the full-color image signal (color signal data) are each subject to expansion and the extended image data is independently generated for each color component signal, other color components The extended image data can be generated without being affected by the state of. Note that the generated extended image data is once written in the line memory 11 by the memory control unit 12, then read from the line memory 11, input to the display device 103, and displayed as an image.

When the image for one line is displayed, the next color signal data for one line is written in the line memory 11 from the color signal processing unit 102, and the same processing as described above is repeated.

As described above, the color signal expansion device 1 performs the time-division processing for each line of the color signal data stored in the line memory 11 so that the color signal data for one frame is input. The processing speed can be improved as compared with the case where the extended image data generation processing is started.

The color signal expansion device 1 terminates the process of generating the extended image data when the extended image data for one frame is generated and displayed on the display device 103.

As described above, in the color signal expansion device 1 according to the present embodiment, the data distribution detection unit 14 determines the data of the color signal based on the distribution state of the data value of the color signal in the spatial pixel array. The additional value to be added to the value is determined, and the data depth expansion unit 15 generates expanded image data in which the data depth of the color signal is expanded while the value corresponding to the additional value is added to the expanded portion. By doing
Compared with the case where the data depth of the color signal is expanded by uniformly adding a predetermined value, it is possible to suppress the occurrence of pseudo contours.

Further, since the line memory 11 is used as the memory used for the expansion processing, the memory capacity required for the expansion processing of the data depth can be minimized. The configuration can be simplified and the price can be reduced.

Embodiment 2. In the above embodiment, the case where the data value is extended by 1 bit has been described.
The present invention is not limited to this, and can be applied to a multi-bit extension process. That is, for a data value of a predetermined color, the difference in the number of bits between the color signal input to the input port 101 and the display device 103 is M bits (M
Is 2 or more), for example, a portion (pixel blocks Bk classified into distribution states ER1 and ER2) in which pixels having constant data values continue is divided by 2 to the power of M, and the data itself to be added, respectively. Can be inclined.

FIG. 6 is a diagram showing data subjected to expansion processing by the color signal expansion device 1 according to the present embodiment configured on the basis of such a principle. FIG. 4 shows an example when M = 2. The color signal expansion device 1 according to the present embodiment has substantially the same configuration as the color signal expansion device 1 according to the above embodiments.

FIG. 6 shows an example of processing for pixels in the distribution state ER1 in which the data value gradually increases. The data distribution detection unit 14 performs the same processing as that of the above-described embodiment on the pixel block B classified into the distribution state ER1.
k is detected, and the pixel block Bk is 4 (2 of “2”).
Power) pixel blocks. Further, the additional values to be added to the data values of the pixels included in each of the four pixel blocks are “0”, “1”,
Determined as "2" and "3". Similarly, for the pixels included in the pixel block Bk classified into the distribution state ER2,
The additional value is “3”, “2”, “1”, “0” in order from the front.
To decide. Further, the additional value is determined to be “0” for the pixels in the distribution state ES. Then, the additional value determined in this way is represented by a 2-bit expression (00,01,10,11 or 11,10,0
1,00) is added as the lower bit of the data value of the relevant color component.

As described above, the same effect as that of the above-described embodiment can be obtained by the color signal expansion device 1 according to this embodiment. Further, for a predetermined color, even if the difference in the number of bits between the color signal data input to the input port 101 and the extended image data input to the display device 103 is a plurality of bits, the occurrence of pseudo contours is suppressed. You can

Modified Example 3. Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made.

For example, in the above-mentioned embodiment, the additional value determined by the data distribution detecting unit 14 is set to the data depth expanding unit 15.
It has been explained that the extended image data is generated by adding to the data value, but once the extended image data is generated by adding "0" and "0" or "1" is added to the extended image data. After performing the correction process,
It may be displayed on the display device 103. In that case, "0" or "-1" may be added.

Further, the data distribution detecting section 14 detects the distribution state of the data values by detecting the pixel blocks as a pixel group having a constant data value, but the present invention is not limited to this. For example, the distribution state of data values may be detected from the slope of change in data values. That is, any known mathematical method may be used as long as it is a method capable of detecting the range in which the color changes gently.

[0087]

As described above, according to claims 1 to 1.
In the invention described in 6, the additional value to be added to the data value of the color signal is determined based on the distribution state of the data value of the color signal in the spatial pixel array, and the value according to the additional value is expanded. By generating an extended color signal in which the data depth of the color signal is extended while being added to, the occurrence of the pseudo contour is suppressed as compared with the case where the extended color signal is generated by uniformly adding a predetermined value. You can

According to the invention described in claims 4 and 12, by detecting a pixel block in which the number of pixels included in the pixel group is larger than a predetermined lower limit threshold value,
Pixels in which the color changes gently can be detected.

According to the invention described in claims 5 and 13, by detecting a pixel block in which the number of pixels included in the pixel group is smaller than a predetermined upper limit threshold value,
Pixels in which the color changes gently can be detected.

According to the sixth aspect of the present invention, the storage means for storing one line of the color signal is provided, and the additional value determining means is the distribution of the data value of the color signal for one line in the storage means. The additional value is determined based on the state, and the expansion means performs the time-division processing to sequentially generate the expanded color signal for each color signal for one line stored in the storage means, thereby the minimum necessary storage means. The extended color signal can be generated with.

According to the seventh and fifteenth aspects of the present invention, a plurality of color component signals in the full-color image signal are expanded as color signals, and the expanded color signal is generated independently for each color component signal. This makes it possible to generate an extended color signal without being affected by the states of other color components.

In the inventions described in claims 8 and 16, the extension of the color signal is addition of M bits (M is an integer of 2 or more), and the addition value is the number of 2 M powers that can be represented by M bits. By allowing and selecting any of the values of, all possible values of M bits can be used, so that the pseudo contour can be further suppressed.

According to the fourteenth aspect of the present invention, the time-division processing for sequentially generating the extended color signal for each color signal for one line is performed, thereby waiting for the processing until the color signal for one frame is input. It is not necessary and the processing speed can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a block diagram of a color signal expansion device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of data values of R (red) in original image data.

FIG. 3 is a diagram showing a data value when the data value of the color signal data shown in FIG. 2 is reduced by 1 bit to be 5 bits.

FIG. 4 is a diagram showing a data value in the case where the data depth is extended by adding “0” to the data value shown in FIG. 3 as in the conventional case.

5 is a diagram showing a result of the 1-bit extension processing of the data value shown in FIG. 3 by the color signal extension device.

FIG. 6 is a diagram showing data subjected to expansion processing by a color signal expansion device according to the second embodiment.

FIG. 7 is a diagram showing a configuration of a conventional color signal expansion device.

FIG. 8 is a diagram exemplifying data values of R (red) in six pixels (X0 to X5) arranged horizontally in image data.

9 is a diagram showing data values of R (red) after the pixel shown in FIG. 8 has undergone expansion processing by a conventional color signal expansion device.

[Explanation of symbols]

1,100 color signal extender, 101 input port, 1
02 color signal processing unit, 103 display device, 11 line memory, 12 memory control unit, 13 color signal expansion unit, 1
4 data distribution detector, 15 data depth extension, B
k, Bk11, Bk12, Bk21, Bk22 pixel block, ER, ER1, ER2, ER3, ER4, ES
Distribution state, K1 to K14 pixel group, P lower limit threshold, Q upper limit threshold.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 9/64 H04N 1/40 D G09G 5/00 520A F term (reference) 5B057 AA20 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC01 CE02 CE11 CE17 5C066 AA03 AA11 BA20 CA08 EC06 GA01 GB03 KA12 KE02 KE09 KF05 KM11 LA02 5C077 MP08 PP32 PP37 PP61 PQ22 RR06 5C079 HB01 LA02 LB01 MA03 NA03 5C082 BA12 BA34 BA81 DA35 CA53 BB15 CA15

Claims (16)

[Claims] 1. An apparatus for expanding a color signal, wherein an additional value to be added to the data value of the color signal is determined based on a distribution state of the data value of the color signal in a spatial pixel array. A color signal extension comprising: an additional value determination means; and an extension means for generating an extended color signal in which the data depth of the color signal is extended while giving a value according to the additional value to the extended portion. apparatus. 2. The color signal expansion device according to claim 1, wherein the additional value determining means sets the pixel block as a group of pixels in which the data value of the color signal is substantially constant and is spatially continuous. Pixel block detection means for detecting, and adjacent pixel determination means for determining the additional value according to the change state of the data value of the color signal in each of the pixel adjacent to the pixel block and the pixel included in the pixel block. A color signal expansion device comprising: 3. The color signal expansion device according to claim 2, wherein the pixel block detection unit selects only the pixel blocks in which the number of pixels included in the group of pixels is within a predetermined range. A color signal expansion device characterized by detecting as. 4. The color signal expansion device according to claim 3, wherein the pixel block detection unit selects a pixel block in which the number of pixels included in the pixel group is larger than a predetermined lower threshold value. A color signal expansion device characterized by detecting as. 5. The color signal expansion device according to claim 3, wherein the pixel block detection unit sets the number of pixels included in the pixel group smaller than a predetermined upper limit threshold, A color signal expansion device characterized by being detected as a pixel block. 6. The color signal expansion device according to claim 1, further comprising storage means for storing one line of the color signal, wherein the additional value determination means is the addition value determination means. The additional value is determined based on a distribution state of data values in the color signal for one line in the storage means, and the expansion means expands for each color signal for one line stored in the storage means. A color signal expansion device, characterized by performing a time-division process for sequentially generating color signals. 7. The color signal expansion device according to claim 1, wherein a plurality of color component signals in a full-color image signal are each expanded as the color signal, and the expansion color signal is , A color signal expansion device which is generated independently for each color component signal. 8. The color signal extension device according to claim 1, wherein the extension of the color signal is addition of M bits (M is an integer of 2 or more), and the addition value is A color signal expansion device, wherein any of the values of the M-th power of 2 that can be represented by M bits is selected. 9. A method of expanding a color signal, wherein an additional value to be added to the data value of the color signal is determined based on a distribution state of the data value of the color signal in a spatial pixel array. Color signal extension including an additional value determination step and an extension step of generating an extended color signal in which the data depth of the color signal is extended while giving a value according to the additional value to an extended portion. Method. 10. The color signal expansion method according to claim 9, wherein the additional value determining step determines a pixel block as a group of pixels in which the data value of the color signal is substantially constant and is spatially continuous. A pixel block detecting step of detecting, and an adjacent pixel determining step of determining the additional value according to a change state of a data value of the color signal in each of a pixel adjacent to the pixel block and a pixel included in the pixel block, A method for extending a color signal, comprising: 11. The color signal extending method according to claim 10, wherein in the pixel block detecting step, only those pixels in which a number of pixels included in the pixel group are within a predetermined range are included in the pixel block. A color signal expansion method characterized by detecting as. 12. The color signal extending method according to claim 11, wherein in the pixel block detecting step, the pixel block in which the number of pixels included in the group of pixels is larger than a predetermined lower limit threshold value. A color signal expansion method characterized by detecting as. 13. The color signal extending method according to claim 11, wherein in the pixel block detecting step, the number of pixels included in the pixel group is smaller than a predetermined upper limit threshold, A color signal expansion method characterized by detecting as a pixel block. 14. The color signal expansion method according to claim 9, further comprising a storage step of storing one line of the color signal, wherein the additional value determination step is the storage step. Determining the additional value based on the distribution state of the data values in the color signals for one line stored by, and the expanding step includes expanding for each color signal for one line stored in the storing step. A color signal expansion method, characterized in that time-division processing for sequentially generating color signals is performed. 15. The color signal extension method according to claim 9, wherein a plurality of color component signals in a full-color image signal are each subject to extension as the color signal, and the extension color signal is , A color signal expansion method which is generated independently for each color component signal. 16. The color signal extension method according to claim 9, wherein the extension of the color signal is addition of M bits (M is an integer of 2 or more), and the addition value is A method for extending a color signal, wherein any of the values of the number of powers of 2 that can be represented by M bits is selected.