JP2590882B2 - Image signal processing apparatus and processing method - Google Patents

Description

Description: TECHNICAL FIELD 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 capability of about 2,000 pixels × 2,000 pixels, so if the color display capability per pixel is increased, the size of the display memory becomes too large. For example, 1
If 8 bits are assigned to each of red, green, and blue in one pixel, 24 bits are required for one pixel, so the total size is 24 bits x 2000 pixels x 2000 pixels = 96000000 bits 11.4 megabytes In this case, it takes a lot of time to process the image, or only a small number of images can be stored (saved) even if a hard disk drive is used. I will.

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. 5 shows an example thereof, in which (1) is a display memory, and in this memory (1), an address corresponding to horizontal scanning and vertical scanning of a color picture tube (not shown) is synchronized with a clock CK. Then, the display data DATA of the image is taken out. In this case, for example, as shown in FIG. 6, 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 densities 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. Output data DATR to DATB of memories (21) to (23)
Since there are 24 bits in total and can take 2 ²⁴ = 16777216 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 red, green, and blue colors, only 8 bits / 32.7 bits are allocated on average, 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 processing apparatus for processing color compression information formed from a plurality of color components of each pixel constituting an image signal, wherein the color compression information is adjacent to a plurality of color components. The color compression information is obtained by selecting a color component having the largest change in level information with the pixel, compressing the selected color component, and an identification code indicating the color component. Receiving means, color component data generating means for generating color component data corresponding to the color compression data, and color component data corresponding to the color compression information of the same color component are supplied next. And a color component data holding means for holding color component data based on the instruction signal corresponding to the identification signal until updated.

[Action]

According to the present invention, a larger number of colors can be simultaneously produced than in the conventional art, and thereby 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) has 8 bits as described above, but this data DATA is data that has been color-compressed according to, for example, the flowchart shown in FIG. Has a format.

That is, in FIG. 2, Ri, Gi, and Bi are original data before color compression, for example, data captured by a video camera or the like, and the red, i. This is digital data indicating green and blue levels by 8 bits.

Then, in step (101), R ₀ = 128, G ₀ = 128, B ₀ = 128 i = 1 are set as initial values. Then, in step (102), data Ri to Bi of the i-th pixel are Data R _{i-1 to} B _{i-1 of the} previous pixel
ΔR = | Ri−R _i−1 | ΔG = | Gi−G _i−1 | ΔB = | Bi−B _i−1 | Value ΔR ~
The largest value of ΔB is determined.

When the value ΔR is the maximum (ΔR> ΔG, ΔR> ΔB), in step (104), the data Ri is converted from 8-bit data (original data) to 6-bit data (color compressed data) Rc. , As shown in FIG.
"10" is added to the upper part of the data Rc 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 is
The bits b ₇ and b ₆ are set to an identification code “10” indicating that the data is red data, and the remaining 6 bits b _{5 to} b ₀ have information on the red density of the i-th pixel (9).

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 have density information that 6 bits b ₅ ~b _0.

Further, in step (103), the value ΔG is maximized (Δ
G> ΔR, ΔG> ΔB), in step (105), the data Gi is replaced with the data Ri in step (104).
Are processed in the same way as the data Gc. However, the data
In gc, as shown in FIG. 3, only the most significant bit b ₇ is an identification code "0", the remaining 7 bits b ₆ ~b ₀ is the density information.

In step (103), the value ΔB is maximized (ΔB
> ΔR, ΔB> ΔG), in step (106), the data Bi is processed in the same manner as the data Ri in step (104) to be data Bc. However, data Bc
In the upper two bits b _7, b ₆ is an identification code "11", the remaining 6 bits b ₅ ~b ₀ is the density information.

Then, step (104), (105) or (106)
In step (107), the data Rc, Gc or Bc formed by any of
Is the data DATA of the i-th pixel (9) at the i-th address
Stored as

Then, in step (108), the value i is incremented by “1”, and the next pixel (9) is set as a processing target. In step (109), whether or not the above processing has been performed on all the pixels (9) Is determined, and if there is a pixel (9) that has not been processed, the processing after step (102) is performed similarly.

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

Further, the memories (21) to (23) for the color look-up table have 256 addresses and
The address has a capacity of 9 bits. Then, in the memory (21), the upper two bits of the address A ₇ to A ₀
When A ₇ and A ₆ become the value of the red identification code “10”, the most significant bit D ₈ of the data D _{8 to} D ₀ becomes “1”, and
As lower address A ₅ to A ₀ color data to be displayed on is output as the lower bit D ₇ to D _0, predetermined data is stored. That is, in the memory (21), 80H
~BFH the address (H represents a _{hexadecimal), D 8 = "1"} , D 7 ~D 0 =
"Data of the color to be displayed" is stored.

Further, in the memory (22), when the most significant bit A ₇ of the address A ₇ to A ₀ becomes equal to "0" in the green of the identification code, the most significant bit D ₈ data D ₈ to D ₀ is " such that 1 ", and, as the color data to be displayed in the lower address a ₆ to a ₀ is output as the lower bit D ₇ to D _0, predetermined data is stored. That is, in the memory (22), the 0~7FH _{address, D 8 = "1",} D 7 ~D 0 = "color of data to be displayed" is stored. In addition, memory (2
In 3), when the upper two bits A ₇ and A ₆ of the addresses A _{7 to} A ₀ become the value of the blue identification code “11”, the data D _{8 to} D ₈
As the upper bit D ₈ top is "1" _0, and the color of the data to be displayed in the lower address A ₅ to A ₀ is lower bit D ₇ ~
As it will be output as D _0, predetermined data is stored. That is, in the memory (22), the COH~FFH _{address, D 8 = "1",} D 7 ~D 0 = "color of data to be displayed" is stored.

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 "10", the memory (21) output data DATR most significant bit D ₈ only becomes "1" of, this bit D ₈ is lower 8 bits D ₇ to D ₀ data DATR latch The signal is latched by (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 "10", the memory (22), ( 23), the most significant bits D ₈ and D ₈ of the output data DATG and DATB do not become “1”. Therefore, the data DATG and DATB are latched (3
2) and (33) are not latched, and the data DATG and DATB at the time of the previous latch are retained.

This state in the latch (31) is maintained until the next red data Rc is fetched from the memory (1), that is, until the density change of red becomes larger than the density change of other colors.

If the data DATA from the memory (1) is green data Gc or blue data Bc, the upper bit
b ₇ or data DATG or DATB according to b _7, b ₆
Since the upper bit D ₈ top is "1", the data DATG or lower eight bits D ₇ to D ₀ of DATB is latched in the latch (32) or (33), D / A converter (42) or (4
The green signal G or the blue signal B is extracted from 3).

Thus, three primary color signals R and B can be obtained,
In this case, according to the present invention, since 6 bits are assigned to red and blue and 7 bits to green, one color is represented by 19 bits. Therefore, 2 ¹⁹ = 524288 colors are simultaneously displayed. Since it can be colored, even a natural image can be displayed with a sufficient gradation and a natural and glossy color can be projected.

In addition, since the display after the change is preferentially performed for a color having a large density change, the resolution is less deteriorated, and the gradation is insufficient due to the lack of the number of quantization bits as shown in the example of FIG. A much higher resolution can be obtained than when the resolution is reduced.

Moreover, only for the color data with a large density change,
Since it is used with an identification code indicating the color,
The memory (1) does not increase in capacity. Furthermore, no special color compression circuit is required, and the memory (21) to
This can be dealt with simply by mapping (23).

Incidentally, in the above, the latch enable signal from the upper bit b ₇ to b ₆ of the data DATA for the latch (31) - (33), be formed by an AND circuit and an inverter, a memory (21) to (23) is one address May have an 8-bit capacity. In that case, the memory (21) ~
The order of (23) and the latches (31) to (33) can be reversed.

Further, in the above description, the data DATA (Rc, Gc or Bc) is stored in the memory (1) in the step (107). However, actually, the data is stored in the hard disk or another memory, and the necessary processing is terminated. Thereafter, the data may be transferred to the memory (1). 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. And 6 bits for red and blue,
Since 7 bits are allocated to green, one color is represented by 19 bits, and therefore, 2 ¹⁹
= 524288 colors can be simultaneously generated, so that even natural images can be displayed with sufficient gradation and natural glossy colors can be projected.

In addition, since the display after the change is preferentially performed for a color having a large density change, the resolution is less deteriorated, and the gradation is insufficient due to the lack of the number of quantization bits as shown in the example of FIG. A much higher resolution can be obtained than when the resolution is reduced.

Moreover, only for the color data with a large density change,
Since it is used with an identification code indicating the color,
The memory (1) does not increase in capacity. Furthermore, no special color compression circuit is required, and the memory (21) to
This can be dealt with simply by mapping (23).

[Brief description of the drawings]

FIG. 1 is a system diagram of an example of the present invention, and FIGS. 2 to 6 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] 1. An image processing apparatus for processing color compression information formed from a plurality of color components of each pixel constituting an image signal, wherein the color compression information includes information on an adjacent pixel among the plurality of color components. The color compression data obtained by selecting the color component having the largest change in the level information of the color component and compressing the selected color component, and an identification code indicating the color component. Receiving means for receiving; color component data generating means for generating color component data corresponding to the color compression data; and supplying the color component data corresponding to the color compression information of the same color component. An image signal processing device comprising: color component data holding means for holding color component data based on an instruction signal corresponding to the identification signal until updated by data. 2. An image processing method for processing color compression information formed from a plurality of color components of each pixel constituting an image signal, wherein the color compression information includes an image signal of a plurality of color components and an adjacent pixel of the plurality of color components. The color compression data obtained by selecting the color component having the largest change in the level information of the color information and compressing the selected color component, and an identification code indicating the color component. Receiving, generating color component data corresponding to the color compression data, and then supplying the color component data corresponding to the color compression information of the same color component until the color component data is updated by the color component data; An image signal processing method, wherein the color component data is held based on an instruction signal corresponding to the signal.