JPS5947913B2 - Color image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image processing device, and particularly to a color image processing device that efficiently encodes a color image by dividing a two-dimensionally distributed image signal into two-dimensional small blocks and processing the two-dimensionally distributed image signals. The present invention relates to a color image processing device for decoding/decoding.

As conventional color image encoding methods, the ΔPCM method, the DPCM method, and the like are known as encoding methods mainly for the purpose of transmitting television signals.

Among these, the ΔPCM method samples the television signal with an appropriate clock, for example, about 9 to 10 MHz, compares the signal level at each sampling point with the signal level at the immediately preceding sampling point, and encodes the difference as a PCM code. It is a method. In addition, the DPCM method predicts the signal level at each sampling point using the values of the pixel immediately before it and the pixel directly above the scanning line above it, and encodes the difference between the predicted value and the actual signal level. It is a method.
With this kind of encoding method, the encoding for one TV screen is
This must be performed during the transmission time of 33 ms for one screen, and the processing is limited to simple ones, and the amount of code for one screen must be approximately constant. For this reason, the amount of code required is about 3 to 4 bits per pixel, and there is a limit to the high compression coding of images. The present invention relaxes restrictions on image encoding time, utilizes local properties of images, and introduces image processing technology to encode images, reduce the amount of code per screen, and utilize this for information storage, information transmission, etc. It is intended to.

FIG. 1 is a diagram explaining the principle of the encoding method of the present invention.
, , represents the pixel in the i-th row and j-th column taken on the target screen.

If the value of a pixel P, is denoted by [P,,], an image is generally expressed by a two-dimensional distribution of [P,,].
Therefore, encoding the image means encoding the value [P,,] of each pixel. Various methods can be considered for displaying color images, but normally pixels are displayed in red, green, blue (R, G,
B) Separation into the three primary colors or luminance information Y and color information I
It is well known that any color image can be expressed by decomposing and displaying the three components of , Q. In the present invention, an image is also decomposed into three components, R, G, and B or Y, I, and Q, and one plane is assigned to each component, and the image is expressed using three planes. FIG. 2 shows an explanatory diagram illustrating the encoding method according to the present invention of two-dimensional information possessed by one plane of an image. In the figure, 100 indicates one plane corresponding to a color image separated into three components of RGB or YIQ, and 101 indicates one plane 100, for example, 4×4. represents one image block divided into units of pixels. In the encoding method according to the present invention, encoding of l planes is performed using this image block 101 as a unit.
That is, in one block 101::H2l-Skin=:
Lee: ;.帥一゜tone ingredient Ak.

, ak, and the resolution component element, , ~R, , . ,,f,
Encode using . Here these values AkO, akl
,r,,~R,f3,,. ,, is given by.

Bk here. is a pixel P, whose luminance value is smaller than the threshold Tk among Bk pixels. The subset of Bk, Bk, is the pixel P, whose luminance value is greater than or equal to the threshold Tk, among the pixels of Bk.
, a subset of Bk consisting of Mk. , mk, are Bk, respectively. , Bk, represents the number of pixels. Here AkO, ak,
is called the gradation component of the set Bk. In this case, each pixel in the pixel block Bk is assigned to a mutually exclusive block BkO.
, Bkl.

So, for example, Bk out of 16 pixels in Bk. Assign "0" to the pixels belonging to P, and "1" to the pixels belonging to Bk. At this time, this "0""1" pattern is assigned to the pixels P,, in an appropriate order, for example, P,,; PI, H; Plj. ，
2Plj+3; P1+1, j; P1+1, j+1; I゜゜゜゜゜; Pattern R arranged in the order of P1+3, j+3
lj; Rlj+1; ゜゜゜゜゜゜; r1+3,j+
3 is called the resolution component of block Bk. In this way, the state of one block Bk is the gradation component A. , a, and resolution component element 1J, r1, j+V゜e゜゜dl+3,J+
It can be approximated by 3. Of these, the gradation component Ak.

, ak, are determined from the values of block Bk only, but these values are considered to have a deep correlation with the gradation components of adjacent blocks Bk-,. Therefore, the tone component Ak
. , ak, the sum component Akm, the difference component Akd, and the difference Dkm between blocks of Akm are defined as follows; Akd and Dkm represent the state of block Bk. In this way, the values of Akd and Dkm are Ak.

, ak, the value is concentrated near o and Ak. ,ak,
can be encoded using fewer bits than encoding it as is. That is, the state of each plane in which a color image can be separated into three primary colors is divided into a large number of blocks Bk, and the gradation components of the image are divided into Akd and D corresponding to each block Bk.
km, and the resolution information is, for example, rι,R if the block size is 4 x 4 pixels. ,f,,...
R,,,,,,. , , can be expressed as information. In this encoding method, tone component Ak in one block Bk
When the difference in Akl is small, that is, the gradation of this block is the average value A shown by equation (4).
Approximate encoding is possible using only kV.

In this case as well, the difference Dk between block Bk and the sum component of the immediately preceding block. n can be defined as in equation (5) using equation (4). It is clear that there is no need to encode the resolution component when the average value is used in this way.

In the above-mentioned encoding method, AkO and akl as gradation information or Dkm and akd as gradation information and Ri as resolution information are output as encoded outputs for each block Bk. When using this encoding method, it is possible to encode a normal natural image with approximately 1 bit per pixel per plane, and when each of the three primary colors is encoded using this method, it is possible to encode with approximately 1 bit per pixel for each plane. It can be encoded with The encoding system of the present invention utilizes this principle, and FIG. 3 is a block diagram showing the configuration of the encoding apparatus of the present invention.

300 is a target color image, 301 is an image input unit,
302 is a three primary color separation section, 3031, 3032, 3033
A samples the signal of one plane of an image that has been decomposed into three planes and converts it into a digital signal.
/D conversion units 3041, 3042, and 3043 are buffer memories each capable of storing pixel information for one block; 3051, 3052, and 3053 are three-plane signal encoding processing units; and 306 is a code storage file unit.

Next, the operation of the encoding device will be explained using FIG.

First, a color image 300 is scanned by an image input section 301 and sent to a three primary color separation section 302 . In this case, the image input unit 301 corresponds to a normal color television camera and has the same mechanism as a three-tube color television camera, and when the target three primary color separations are RG and B, the three primary color separation unit 302
The signal from the image input unit 301 may be sent as output as it is. Further, when the three primary color separations are Y, I, and Q, the three primary color separation section separates them into Y, I, and Q by a matrix circuit normally used in a color television camera. The scanning method of the image input section 301 is adapted to the shape of the blocks that divide each plane, and in the case of a 4.times.4 pixel block, it is configured such that scanning can be performed in units of blocks. In addition, if the scanning method is a raster scanning method similar to that of a normal camera, processing in units of blocks can be easily performed by providing a buffer memory 304 with a buffer memory capacity for multiple scanning lines corresponding to the size of the blocks, which will be described later. That should be obvious. Next, the signals extracted in this way and separated into the three primary colors are sent to an A/D converter 30 for each plane.
31, 3032, and 3033, and is converted into a digital signal and written as digital luminance information to buffer memories 3041, 3042, and 3043 in units of blocks.

This luminance information for each plane is stored in the encoding processing unit 3051,
3052 and 3053, the difference component Akd for each block and the difference Dk. n and resolution component element 13;...; R, X3, , +3. The calculations of equations (1) and (2) are performed on a block-by-block basis, and it is clear that this processing can be easily realized using an existing microprocessor or the like. The information encoded in this manner is stored in the code storage file section 206 as a digital code. Note that in the configuration diagram of this encoding device (FIG. 3), buffer memories 304, ~3043, encoding processing units 305, ~30
53 is expressed in a form in which each of the three systems is configured independently, but it is clear that depending on the memory capacity and the ability of the microprocessor, processing can be performed in a time-sharing manner with one microprocessor without necessarily having to prepare them independently. Probably.

FIG. 4 shows an example of a configuration of a decoding position for decoding the code encoded by the above encoding device and stored in the code storage file 306 to obtain a display image signal.

In the figure, 4001, 4002, 4003 are decoding processing units corresponding to each plane, 4011, 4012, 4013 are buffer memory units with a capacity equivalent to the number of blocks per block or one screen width, and 402 is a color signal signal. A compositing unit 403 is a color image display unit. Next, the operation of the decoding device will be explained using FIG.

The encoding device encodes the difference component Akd in units of blocks, and the difference Dk between blocks. n, and the codes stored as resolution component elements I, . By performing inverse calculations of equations (1) to (5), each plane is decoded into luminance information and buffer memory 401, .
401,,401,. Next, the decoding processing section 400
, .about.400, sequentially read out the brightness information for each plane decoded in block units from buffer memories 401, .about.401 in scanning line units and send it to color signal synthesis section 402. The color signal synthesis unit 402 uses R as its encoding format.
, G, B or Y, I, Q, and depending on whether the output monitor signal format is R, G, B or NTSC system, this circuit converts signals between them. can be easily constructed using conventional television technology such as an NTSC encoder. In this decoding device as well, although the decoding processing units 401, .

In the above description, it has been shown that the encoded signal is filed, but it goes without saying that the present invention can be applied to a transmission system that directly transmits the encoded signal via a transmission path.

As explained above, the encoding and decoding device according to the present invention performs encoding using the local correlation of images, so highly efficient encoding is possible, and the code accumulation of color images can be performed with a small amount of code. It is possible to perform or transmit.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram explaining the principle of the encoding method according to the present invention, Fig. 2 is an explanatory diagram explaining the encoding method of two-dimensional information of one plane in which an image is separated into three primary colors, and Fig. 3 4 is a block diagram showing the configuration of an embodiment of the encoding device of the present invention.
The figure shows a block diagram showing the configuration of one embodiment of the decoding device of the present invention. 100...One plane separated into the three primary colors of the image, 101...L unit block of the image, 30
0...Color image, 301...Image input section, 302...3 primary color separation section, 303,,3
03,,303,...A/D conversion section, 304,
,3042,3043...Buffer memory, 3
05,,3052,3053... Encoding processing unit, 306... Accumulation file unit, 400,,40
0. ,400,...decoding processing section, 401,,4
01,,401,... buffer memory section, 402...
. . . Color signal synthesis unit, 403 . . . Image display device.

Claims (1)

[Claims] 1 A three-primary color separation unit that separates a color image signal into three primary color components, an A/D conversion unit that samples the signal for each component and converts it into a digital signal, and each component obtained by the A/D conversion unit A buffer memory section that temporarily stores the corresponding digital image signal, and a buffer memory section that temporarily stores the corresponding digital image signal, and a
The image signal of each component having a dimensional distribution is divided into two-dimensional small blocks, the brightness average value of the brightness values of each pixel belonging to the block is determined for each block, and the brightness average value is used as a threshold. Each pixel in the block is divided into a set of pixels having a luminance value larger than the threshold value and a set of pixels having a luminance value smaller than the threshold value, and a gradation component corresponding to the average luminance value of each of the two sets is calculated. means for obtaining a resolution component corresponding to information indicating which of the two sets each pixel belongs to, means for obtaining a sum and difference value of the gradation components, and a means for obtaining a resolution component corresponding to information indicating which of the two sets each pixel belongs to, a means for obtaining a sum and a difference value of the tone components, and an encoding processing unit configured with means for calculating the difference between the sum of the values obtained by the same means as the gradation components for the block and the sum of the gradation components of the block, The difference information between the small blocks of the sum value of the gradation components of the pixels in the small block, the difference information of the gradation components, and the resolution component are encoded outputs. Image processing device.