JP2590884B2 - Image signal processing apparatus and processing method - Google Patents

Description

The present invention relates to an image signal processing device and a processing method.

[Conventional technology]

In computer graphics, the color display capability is sufficiently if generally 1 pixel per 256 colors (= ^28). That is, it is only necessary to assign 8 bits to one pixel.

However, recently, there has been a demand for processing and displaying a natural image, for example, an image captured by a video camera. In this case, a color display capability of 256 colors per pixel is insufficient.

However, computer graphics have a display capacity of about 2000 pixels × 2000 pixels. Therefore, if the dye display capacity per pixel is increased, the size of the display memory becomes too large. For example, if 8 bits are assigned to each of red, green, and blue in one pixel, 24 bits are required for one pixel. Therefore, as a whole, 24 bits × 2000 pixels × 2000 pixels = 96000000 bits 11.4 In this case, it takes a lot of time to process the image, or only a small number of images can be stored (saved) using a hard disk drive. It becomes scarce.

Therefore, the number of bits per pixel is set to 8 bits, but a method of expanding the color display capability by using a color look-up table has been considered.

FIG. 6 shows an example thereof, wherein (1) is a display memory, which is synchronized with a clock CK from an address corresponding to horizontal scanning and vertical scanning of a color picture tube (not shown) in this memory (1). Then, the display data DATA of the image is taken out. In this case, for example, as shown in FIG. 7, the size of the data DATA for one pixel (9) is 8 bits, and the 8 bits are bits b ₇ , b ₆ ... ₅ ~b ₂ ...... green indicator bit b _1, b ₀ ...... assigned as for blue display. That is, the data DATA is
The bits “b ₇ , b ₆ ”, “b ₅ -b ₂ ”, and “b ₁ , b ₀ ” indicate the red, green, and blue levels (color saturation) of the corresponding pixels, respectively. .

Further, (21) to (23) are mapping circuits for a color look-up table, and in this example, a memory. The memories (21) and (23) each have four addresses, and the memory (22) Has 16 addresses, all memories (21) to (23) have a capacity of 8 bits per address, and each address stores data corresponding to a color to be displayed.

(31)-(33) are 8-bit latches, (41)
(43) are 8-bit D / A converters.

When the data DATA of a pixel in the memory (1) is taken out, the bit b _7, b ₆ is a memory for that red (2
The supplied with corresponding address (bits b _7, the value of the address) from the 8-bit data DATR indicated by b ₆ as the address signal is taken out 1), this data DATR clock
After being latched by the latch (31) by CK, it is supplied to the D / A converter (41) to be converted into an analog red signal R.

Similarly, the bit b ₁ of bit b ₅ ~b ₂ and blue for green data DATA, b ₀ is memory (22), respectively 8 bits from the supplied with corresponding address as their address signal (23) The data DATG and DATB are taken out and supplied to the D / A converters (42) and (43) through the latches (23) and (33) to be converted into analog green signals G and blue signals B. You.

Then, these signals R, G, B are supplied to the color picture tube, so that a color image corresponding to the data DATA in the memory (1) is displayed.

In this case, the data DATA serving as the address signals of the memories (21) to (23) can take 2 ⁸ = 256 values, and the output data DATR to DATB of the memories (21) to (23) are all Since there are 24 bits and can take 2 ²⁴ = 16777216 kinds of values, 256 colors out of 16777216 colors can be displayed simultaneously.

As described above, if the color look-up table is used, many hues and gradations (densities) can be expressed even if the capacity of the display memory (1) is small, and a colorful image can be displayed.

[Problems to be solved by the invention]

However, in the circuit described above, 256 colors are selected out of 16777216 colors, and only these 256 colors are displayed at the same time. May be missing. For example, when displaying glossy fruits, red and blue have only 2 bits allocated,
Since there are four gradations, the quantization is conspicuous, and the color change becomes striped.

Further, considering each of the colors red, green and blue, only 8 bits / 32.7 bits are allocated in parallel, so that the gradation is insufficient, the resolution is reduced, and the image quality is greatly deteriorated.

An object of the present invention is to propose an image signal processing apparatus and a processing method capable of simultaneously producing a large number of colors as compared with the related art, thereby obtaining an image having a sufficient gradation.

[Means for solving the problem]

An image signal processing apparatus according to the present invention is an image signal processing apparatus for processing compression information formed from a plurality of color components of each pixel constituting an image signal, wherein the plurality of color components and the luminance corresponding to the plurality of color components are provided. From the component, based on the result of comparing the level change amount of each color component of each color component and the color component of the already processed pixel with the level change amount of each color component and the luminance component, a plurality of color components or luminance components are calculated. 1
And selecting the one, compressing the selected color component or luminance component, and identifying code indicating the selected color component or luminance component to form compression information, and receiving the compression information. Receiving means, instruction signal generating means for generating color component data corresponding to the compressed data, and generating an instruction signal corresponding to the identification code; and color component data corresponding to the same color component or luminance component compression information. Until the color component data is supplied and updated by the color component data.

[Action]

According to the present invention, a larger number of colors can be simultaneously produced than in the related art, whereby an image having a sufficient gradation can be obtained.

〔Example〕

In FIG. 1, a display memory (1) has the same capacity as that described above, and display data DATA of an image is extracted from addresses corresponding to horizontal scanning and vertical scanning of a color picture tube in synchronization with a clock CK.

In this case, the data DATA for one pixel (9) is 8 bits as described above, but this data DATA is data compressed according to the flowchart shown in FIG. 2, for example, and the format shown in FIG. Having.

That is, in FIG. 2, Ri, Gi, and Bi are original data before compression, for example, data captured by a video camera or the like, and the red and green colors of the i-th pixel (9) in one screen. , Digital data indicating the level of blue in 8 bits. Further, the value R ^* is equal to the data Ri-Bi of a pixel when the data Ri-Bi satisfy a predetermined condition. The same applies to the values G ^* and B ^* .

Then, in step (101), the initial value as ^{_{R * = 0.3R 1 + 0.59G 1}} + 0.11B 1 G * = R *, B * = R *, i = 1 is set, then step (102) , The luminance data Yi of the i-th pixel is calculated from the data Ri to Bi by Yi = 0.3Ri + 0.59Gi + 0.11Bi, and ΔR = | Ri−R ^* | ΔG = | Gi−G ^* | ΔB = | Bi−B ^* | ΔYr = | Yi−Ri | ΔYg = | Yi−Gi | ΔYb = | Yi−Bi |

Therefore, the values ΔR to ΔB indicate errors between the data Ri to Bi and the data R ^{* to} B ^* , respectively, and the value ΔYr
.DELTA.Yb indicate errors between the data Yi and the data Ri to Bi.

Then, in step (103), i. The larger one of the errors ΔG and ΔB is set to ΔS. Ii. The larger one of the errors ΔR and ΔB is set to the error Δ
Iii. Of the errors ΔR and ΔG, the larger one is the error Δ
Iv. Among the errors ΔYr to ΔYb, a process of setting the maximum error to an error ΔV is performed. Subsequently, in step (104), the errors ΔS to ΔV are compared, and the minimum error among the errors ΔS to ΔV is determined. An error is determined.

Then, in this case, if the value S is the minimum (ΔS <ΔT, ΔS <ΔU, ΔS <ΔV) among the errors ΔS to ΔV, this is determined in step (103) by the errors ΔG and ΔB. This means that the larger error is smaller than the other errors. Therefore, the data Gi, Bi at this time can be substituted with the data G ^* , B ^* , and there is no need to prepare the green and blue data Gi, Bi of the i-th pixel in the memory (1). . Further, this allows the red data Ri of the i-th pixel to be prepared in the memory (1), and only the data R ^* needs to be updated to the data Ri.

The same processing can be performed when the errors ΔT to ΔV are the minimum.

Therefore, when the error ΔS is minimum, the step (10
In 5), R ^* = Ri is set, and the data Ri is converted from 8-bit data (original data) to 6-bit data (compressed data) Rc, and as shown in FIG. "00" is added as an identification code indicating that the data is red data, and the data Rc has 8 bits as a whole. Therefore, the data Rc has the identification code “00” indicating that the upper two bits b ₇ and b ₆ are red data, and the remaining six bits b _{5 to} b ₀ are the red color of the i-th pixel (9). It has gradation information.

At this time, the 6 bits b _{5 to} b ₀ of the data Rc are obtained by allocating 6 bits to an effective section of the frequency distribution of the original data, for example, as shown in FIG. Therefore, data Rc will have sufficient quantization levels without only the 6 bit b ₅ ~b ₀ no gradation information.

Further, when the error ΔT is minimum in step (104), G ^* = Gi is set in step (106), and the data Gi is processed in the same manner as the data Ri in step (105) to become data Gc. . However, in the data Gc, as shown in FIG.
b ₇ and b ₆ are set to the identification code “01”, and the remaining 6 bits b _{5 to} b ₀ are set to gradation information.

When the error ΔU is minimum in step (104), B ^* = Bi is set in step (107), and the data Bi is stored in the data R in step (105).
The data is processed in the same manner as i and becomes data Bc. However, in the data Bc, the upper two bits b ₇ and b ₆ have the identification code “10”.
Is a remains 6 bits b ₅ ~b ₀ is the density information.

Further, when the error ΔV is minimum in step (103), R ^* = Ri, G ^* = G in step (108).
i, ^* = Bi, and the data Yi is stored in step (10
Data Yc is processed in the same manner as data Ri in 5). However, in the data Yc, the upper two bits b ₇ and b
₆ is an identification code “11”, and the remaining 6 bits b _{5 to} b ₀ are gradation information.

Then, the data Rc, Gc, Bc or Yc formed in any of the steps (105) to (108) is stored in the step (109).
Is stored as data DATA of the i-th pixel (9) at the i-th address of the storage means, for example, the memory (1).

Then, in step (110), the value i is incremented by “1”, and the next pixel (9) is processed. Whether or not the above processing has been performed on all the pixels (9) in step (111) Is determined, and if there is a pixel (9) that has not been processed, the processing after step (102) is repeated.

Therefore, in the memory (1), for each pixel (9),
As for the color or luminance having the largest level change with the previous pixel (9), the information of the gradation is stored as data DATA.

Further, the memories (21) to (23) for the color look-up table have 256 addresses and have a capacity of 9 bits per address. Then, in the memory (21), the upper two bits A ₇ of the address A ₇ to A _0, A
_{When 6} becomes the value of the red identification code “00” or the value of the luminance identification code “11”, the most significant bit D of the data D _{8 to} D _0
8 so that the "1" and the data of the level of the red component of the color to be displayed lower bit D ₇ to D ₀ (red data DATR)
The predetermined data is stored so as to be output as. That is, in the memory (21), the 00H~3FH address and COH~FFH address (H represents a _{hexadecimal), D 8 = "1"} , D 7
DD ₀ = “red data DATR” is stored.

Further, in the memory (22), when the upper two bits A _7, A ₆ of the address A ₇ to A ₀ becomes the value "11" of the identification code of the green identification code values "01" or intensity, data D ₈ ~D ₀
As such, and the upper bit D ₈ top is "1", so that the data level of the green component of the color to be displayed is outputted as a lower bit D ₇ to D ₀ (green data DATG), a predetermined data Is stored. That is, in the memory (22), the 40H~7FH address and COH~FFH _{address, D 8 = "1",} D 7 ~D
₀ = “Green data DATG” is stored. further,
In the memory (23), when the upper two bits A _7, A ₆ of the address A ₇ to A ₀ becomes the value "11" of the identification code of the blue identification code values "10" or intensity, data D ₈ DD _{0 so that} the most significant bit D ₈ becomes “1”, and the data of the blue component level of the color to be displayed is the lower bits D ₇ 〜D ₀ (blue data
The predetermined data is stored so as to be output as (DATB). That is, in the memory (22), 80H to B
The FH address and COH~FFH _{address, D 8 = "1",} D 7 ~D 0 = "blue data DATB" is stored.

At the addresses COH to FFH of the memories (21) to (23), the same data is stored in the memories (21), (22) and (23).

The latches (31) to (33) have memories (21) to
Upper bits D ₈ to D ₈ uppermost is supplied as a latch enable signal (23).

According to such a configuration, the data DA is stored in the memory (1).
When TA is retrieved, this data DATA is stored in memory (21) ~
The data DATR to DATB are supplied to (23) and converted into some data DATR to DATB, and the data DATR to DATB are supplied to latches (31) to (33).

Then, in this case, the data DATA from the memory (1)
Is red data Rc, for example, the upper 2 bits
b _7, b ₆ is so "00", only the most significant bit D ₈ of the output of the memory (21) becomes "1", the data DATR This bit D ₈
Is latched by the latch (31), so that the red signal R is extracted from the D / A converter (41).

At this time, the data DATA is stored in the memories (22) and (23).
Because it is also supplied to the memory (22), data from (23) DATG, DATB has also been output, the upper bit b ₇ data DATA, b ₆ is so "00", the memory (22), ( The most significant bits D ₈ and D ₈ of the output of 23) do not become “1”, so that the data DATG and DATB are not latched by the latches (32) and (33), and are latched before that. The data DATG and DATB at the time of execution are kept held.

This state in the latch (31) is held until the next red data Rc is fetched from the memory (1), that is, until the red gradation change becomes larger than the other color gradation changes. .

Further, the data DATA from the memory (1) is, if the green data Gc or blue data Bc, the most significant bit of the output of the memory (22) or (23) in accordance with the upper two bits b _7, b ₆ since D ₈ is "1", the data DATG or DATB is latched in the latch (32) or (33),
The green signal G or the blue signal B is extracted from the D / A converter (42) or (43).

Further, the data DATA from the memory (1) is, if the data Yc of luminance, the upper two bits b _7, b ₆ is so "11", equal to all of the memory (21) to (23) data DATR with ~DATB is output, all of the most significant bit D ₈ to D ₈ becomes "1", therefore, the latch (31)
The data DATR to DATB are simultaneously latched by (33) to (33), and signals RB having luminance information (brightness information) are extracted from the converters (41) to (43).

Therefore, for each pixel (9), it is determined from the identification code whether the data DATA is red to blue or luminance data, that is, for each pixel (9), the floor of the pixel (9) with the previous pixel (9) is determined. The color or luminance having the largest tonal change is determined, the data of the latches (31) to (33) is updated in accordance with the color or luminance having the largest change, and the signals RB are extracted.

Thus, three primary color signals R and B can be obtained,
In this case, according to the present invention, since 6 bits are allocated to each of red to blue, one color is represented by 18 bits. Therefore, 2 ¹⁸ = 262144 colors can be simultaneously generated, so that a natural image can be generated. Even with this, it is possible to display with a sufficient gradation and to project a natural and glossy color.

In addition, the display after the change is preferentially performed for the color having a large gradation change, and the concept of luminance is adopted. When the luminance change of the original data is large, the signals R to B are changed according to the identification code “11”. Since the luminance of the display screen is changed by changing the bit at the same time, an extremely high resolution can be obtained.

Further, since the concept of luminance is adopted, for example, the boundary between a black portion and a white portion is not colored. That is, at the boundary between the black portion and the white portion, for example, as shown in FIG. 5, all of the red to blue data Ri to Bi change significantly at the same time. If the signals Yr to ΔYb, ΔV are not adopted, the values ΔR, ΔG,
The smallest of ΔB, for example, ΔS <ΔT, ΔS <ΔU
, The value ΔS is determined to be the minimum, and step (105)
, The data Rc is regarded as the data DATA of the i-th pixel (9). Therefore, at the time of display, the i-th pixel (9) has, for green and blue, an earlier pixel, for example, the (i−1) -th pixel (9). In addition to the level 9), the level for green is the level after the change. Therefore, the i-th pixel (9) is colored red because the red level is higher than the green and blue levels. The same occurs for the next (i + 1) -th pixel (9).

However, according to the present invention, since the signals ΔYr to ΔYb, ΔV are formed by adopting the concept of luminance, the levels of the signals R to B at the i-th pixel (9) change at the same time, and therefore, the coloring is performed. Never be.

In addition, since only the data of the color or luminance having a large gradation change is used after adding the identification code indicating the color or luminance, the capacity of the memory (1) does not increase. Furthermore, a special color compression circuit is not required, and can be dealt with only by mapping with the memories (21) to (23).

In the above description, the upper bits b ₇ , b ₆
When the latch enable signals for the latches (31) to (33) are formed from the AND circuit and the inverter, the memories (21) to (23) may have a capacity of one address of 8 bits. In that case, the order of the memories (21) to (23) and the latches (31) to (33) can be reversed.

Further, in the above description, the data DATA is stored in the memory (1) in the step (108). However, actually, the data is stored in the hard disk or another memory, and after the necessary processing is completed, the data (DATA) is stored in the memory (1). Just transfer it. The processing in FIG. 2 can be realized by either software or hardware.

〔The invention's effect〕

According to the present invention, a larger number of colors can be simultaneously produced than in the related art, whereby an image having a sufficient gradation can be obtained. Since 6 bits are allocated to each of red to blue, one color is represented by 16 bits. Therefore, 2 ¹⁸ = 262,144 colors can be simultaneously generated. In addition to being able to display in tones, it is possible to detect natural and shiny colors.

In addition, the display after the change is preferentially performed for the color having a large gradation change, and the concept of luminance is adopted. When the luminance change of the original data is large, the signals R to B are changed according to the identification code “11”. Since the luminance of the display screen is changed by changing the bit at the same time, an extremely high resolution can be obtained.

Further, since the concept of luminance is adopted, for example, the boundary between a black portion and a white portion is not colored. That is, at the boundary between the black portion and the white portion, for example, as shown in FIG. 5, all of the red to blue data Ri to Bi change significantly at the same time. If the signals Yr to ΔYb, ΔV are not adopted, the values ΔR, ΔG,
The smallest of ΔB, for example, ΔS <ΔT, ΔS <ΔU
, The value ΔS is determined to be the minimum, and step (105)
, The data Rc is regarded as the data DATA of the i-th pixel (9). Therefore, at the time of display, the i-th pixel (9) has, for green and blue, an earlier pixel, for example, the (i−1) -th pixel (9). In addition to the level 9), the level for green is the level after the change. Therefore, the i-th pixel (9) is colored red because the red level is higher than the green and blue levels. The same occurs for the next (i + 1) -th pixel (9).

However, according to the present invention, since the signals ΔYr to ΔYb, ΔV are formed by adopting the concept of luminance, the levels of the signals R to B at the i-th pixel (9) change at the same time, and therefore, the coloring is performed. Never be.

In addition, since only the data of the color or luminance having a large gradation change is used after adding the identification code indicating the color or luminance, the capacity of the memory (1) does not increase. Furthermore, a special color compression circuit is not required, and can be dealt with only by mapping with the memories (21) to (23).

[Brief description of the drawings]

FIG. 1 is a system diagram of an example of the present invention, and FIGS. 2 to 7 are diagrams for explanation thereof. (1) is a display memory, (21) to (23) are mapping memories, (31) to (33) are latches, and (41) to (43) are D /
A converter.

Claims (2)

(57) [Claims] An image signal processing apparatus for processing compressed information formed from a plurality of color components of each pixel constituting an image signal, comprising: a plurality of color components and a luminance component corresponding to the plurality of color components. Based on the result of comparing the level change of each color component and the level change of each of the color components and the luminance component of the luminance component,
The compressed data obtained by selecting one of the plurality of color components or the luminance component and compressing the selected color component or the luminance component and an identification code indicating the selected color component or the luminance component. Receiving means for composing the compression information and receiving the compression information; instruction signal generating means for generating color component data corresponding to the compressed data and generating an instruction signal corresponding to the identification code; Holding means for holding the color component data based on the instruction signal until the color component data corresponding to the compression information of the same color component or the luminance component is supplied and updated by the color component data. Characteristic image signal processing device. 2. An image signal processing method for processing compression information formed from a plurality of color components of each pixel constituting an image signal, the method comprising: calculating a plurality of color components and a luminance component corresponding to the plurality of color components; Based on the result of comparing the level change of each color component and the level change of each of the color components and the luminance component of the luminance component,
The compressed data obtained by selecting one of the plurality of color components or the luminance component and compressing the selected color component or the luminance component and an identification code indicating the selected color component or the luminance component. Composing the compressed information, receiving the compressed information, generating color component data corresponding to the compressed data, generating an instruction signal corresponding to the identification code, and then generating the same color component or luminance component. An image signal processing method, wherein the color component data corresponding to the compression information is supplied, and the color component data is held based on the instruction signal until the color component data is updated by the color component data.