JPH033494A - Picture information transmission system - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency by increasing the compression rate when information quantity is less such as a still picture and selecting a normal compression rate in the case of a moving picture adaptively. CONSTITUTION:A signal processing output is switched in the unit of blocks with an output of a movement detector 6. When a picture is close to a still picture, the signal processing using an inter-frame difference DPCM and MIN- MAX methods is applied and in the case of a moving picture, the signal processing by the MIN-MAX method only is implemented by using a changeover device 12. As soon as the changeover is implemented, the input to a frame memory 10 by a changeover device 9 is switched from a decoding signal subjected to the inter-frame difference DPCM and MIN-MAX method into a signal resulting from a split inverse conversion section 131 by the MIN-MAX method only to rewrite the content of the frame memory 10 thereby preventing the storage of coded errors. Then the redundancy in the timewise direction of the picture information is eliminated to send high definition picture informa tion efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image information transmission system, and particularly to an image information transmission system that enables highly efficient encoding.

[Conventional technology]

2. Description of the Related Art Hitherto, as this type of image information transmission system, for example, a high efficiency encoding system for television signals has been known. In this television signal high-efficiency encoding system, the so-called MIN-MAX method is adopted to reduce the average number of bits per pixel due to the need to narrow the transmission band. This MIN-MAX method will be explained below.

Television signals have strong spatiotemporal correlation. When an image is divided into small blocks, each block often has only a small dynamic range due to local correlation. Therefore, by determining the dynamic range for each block and adaptively encoding it, very efficient compression can be achieved.

Therefore, this encoding will be specifically explained with reference to the drawings.

FIG. 3 is a diagram showing a schematic configuration of an image information transmission system as an example of conventional technology. 101 in the figure is an input terminal, which samples a raster-scanned analog image signal such as a television signal at a predetermined frequency.
Digital image data is input which is digitized into n bits of data per sample. This 2'' gradation digital image data is supplied to the pixel block division circuit 102.

FIG. 4 is a diagram showing how all pixel data for one screen is divided into pixel blocks. Pixel block division circuit 102
First, all pixel data for one screen is stored in a memory, etc., and as shown in Fig. )
Pixel data is read out in units of pixel blocks each consisting of (IXm) pixels of m pixels. That is, output is performed for each data of each pixel block.

FIG. 5 shows the configuration of each pixel block. In the figure, D! ,
l" D m, t indicates each pixel data. The image data output from the pixel block division circuit 102 is input to the maximum value detection section 103, the minimum value detection section 104, and the timing adjustment section 105. Among all the pixel data (D1.r to Dm, 1) in each pixel block, the data having the maximum value (Dmax) and the data having the minimum value (Dmln) are detected by the detection units 103 and 104 and output. Ru.

On the other hand, in the timing adjustment section 105, the maximum value detection section 103 and the minimum value detection section 104 calculate D max , D
All pixel data is delayed by the time necessary to detect min, and the pixel data is sent to the divided value converter 106 in a predetermined order for each pixel block. For example, for each pixel block, Dr, l, D2. l,
D3. r.

...+ D R1e Dl, 2 g... D, 2.
..., D1. (j-1) *...D m,
(z-+), DI, z..., Drn, *, and so on.

In this way, all pixel data (D
r, l−D m, t ) and their maximum value (D
, , , ) and the minimum value (D min ) are input to the division value conversion unit 106, and for each pixel data, the division code ( Δ1,1 to Δm,z) are obtained.

Here, k is an integer smaller than n, and the state of its quantization is shown in FIG. 6(a).

As shown in FIG. 6(a), ΔId is output as a binary code of two bits. The n-bit division code ΔLl obtained in this way and the n-bit D max and D mi
n is a parallel-to-serial (p-s) converter 10, respectively.
7.degree. 107'107' is converted into serial data, and the data selector 108 converts the data into serial data as shown in FIG. Note that FIG. 7 shows transmission data for one pixel block.

The data output from the data selector 108 is first-in first-out memory (FIFO memory)
At step 109, the data is subjected to time axis processing so as to have a constant data transmission rate, and furthermore, a synchronization signal is added at a synchronization adding section 110, and the signal is sent out from an output terminal 111 to a transmission path (for example, a magnetic recording/reproducing system such as a VTR).

Regarding the addition of synchronization signals, for each pixel block,
This may be performed for each of a plurality of pixel blocks. Note that the operation timing of each of the above-mentioned sections is determined based on a timing signal output from the timing control section 112.

FIG. 8 is a block diagram showing a schematic configuration of a receiving side corresponding to the data transmitting side shown in FIG. 3. In FIG. 8, reference numeral 121 is a terminal to which the transmission data encoded with high efficiency on the transmission side described above is input.

The synchronization signal in the input transmission data is sent to the synchronization separator 122.
is separated and supplied to the timing control section 123. This timing control section determines the operation timing of each section on the receiving side based on the synchronization signal.

On the other hand, in the data selector 124, the n-bit data D nux , D min in the aforementioned transmission data,
Each pixel data is divided into bit quantized codes ΔLl between Dm, x, and DITIIn. These are respectively serial-to-parallel (s-p) converters 125. 12
5' is converted to parallel data. Maximum value data D+Tlax s and minimum value data D in each pixel block converted into parallel data by the S-P converter 125
min is latched by latch circuits 126 and 127, respectively, and the latched maximum value data D maw and minimum value data D mln are each output to the divided value inverse converter 128 . On the other hand, the division codes Δ1,1 for each pixel data in each pixel block are divided into s in the predetermined order as described above.
-p converter 125' and supplied to divided value inverse converter 128.

FIG. 6(b) shows the division code ΔL1 and D max , D
Representative value data D't related to the original pixel data from mln
As shown in the figure, the representative value is, for example, D ma! , D m+. is set to the middle of each quantization level divided into two. The n-bit representative value data (D' l,
tmD' ra,j ) will be output for each pixel block in the aforementioned order. Scan converter section 1
In 29, the output data of the divided value inverse transformer 128 is
The data is converted into an order corresponding to raster scanning and output to the output terminal 130 as decoded image data.

[Problem that the invention seeks to solve]

However, the above conventional example utilizes the correlation only between two-dimensional windows of images. Therefore, when transmitting still images or images with little movement, redundancy occurs in the transmitted information on the time axis, resulting in the same information being transmitted repeatedly.
The drawback is that it deteriorates transmission efficiency.

SUMMARY OF THE INVENTION Therefore, in view of the above-mentioned points, an object of the present invention is to provide an image transmission method that can efficiently transmit high-quality image information.

[Means for solving problems]

The image information transmission method according to the present invention is a method for transmitting image information in which one screen is composed of a plurality of pixel data, and the plurality of pixel data for one screen are transmitted every predetermined number of pixel data. The pixel block is divided into multiple pixel blocks, each pixel block is determined whether it belongs to a video area or a still image area in the screen, and based on the determination result, the pixel block within the pixel block that belongs to the video area is determined. Pixel data is encoded and transmitted based on the first encoding method using only pixel data within the same pixel block, and pixel data within a pixel block belonging to a still image area is different from pixel data within the same pixel block. The pixel data of the pixel block is encoded based on the second encoding method and transmitted.

[Effect]

As described above, by performing adaptive transmission according to the state of image information using the image information transmission method of the present invention,
This is to transmit image information with high efficiency.

〔Example〕

Hereinafter, the present invention will be explained using one embodiment of the present invention.

1 and 2 are diagrams showing a schematic configuration of an image information transmission system as an embodiment of the present invention. here,
FIG. 1 shows a transmitting system, and FIG. 2 shows a receiving system. In addition, the first
In FIGS. 3 and 2, the same components as those in FIGS. 3 and 8 are given the same reference numerals and detailed explanations will be omitted.

In the following description, only the differences from the conventional example will be explained.

In FIG. 1, 1 is a subtracter that subtracts the output of the frame memory 10 from the output of the pixel block dividing circuit 102;
3 is an inter-frame maximum value detection unit that calculates the maximum value of the output of the subtracter 1, 3 is an inter-frame minimum value detection unit that also calculates the minimum value, and 4 is from the inter-frame maximum value detection unit 2 to the inter-frame divided value conversion unit 5. a timing adjustment section that adjusts the transmission time of
Reference numeral 6 indicates a motion detection unit that determines motion based on the outputs of the inter-frame maximum value detection unit 2 and the inter-frame minimum value detection unit 3, and 7 indicates each of the above-mentioned units 2. 3. 5 a switch for switching the respective outputs; 8 an adder for adding the outputs of the inter-frame divided value inverse conversion section 128 and the frame memory 10; 9 an output of the adder 8/divided value inverse conversion as an input to the frame memory IO; a switch for switching the output of the section 131; 10 is the frame memory 11 for storing the signal from the switch 9;
1 is a switch that switches the outputs of the maximum value detection section 103, the minimum value detection section 104, and the divided value conversion section 106;
2 is a switch for inputting the signal from either switch 7 or 11 to the P-8 converter 13; 13 is switch 1;
The p-s converter converts the signal from 2 into parallel to serial and adds the output of the motion detection section 6, and 14 is a timing control section that controls the timing of each circuit.

In FIG. 2, 20 is an S-P converter that performs serial-to-parallel conversion of the signal from the input section 121, 21 is an adder that adds the output of the divided value inverse conversion section 128 and the output of the frame memory 23, and 22 is a scan A switch selects the divided value inverse conversion section 128 or the output of the adder 21 as an input to the converter 129, 23 is a frame memory that stores the signal from the switch 22, and 24 is a motion signal from the output of the S-P converter 20. A motion signal separation unit 25 is a timing control unit that controls the timing of each circuit from the output of the synchronization separation unit 122.

Next, the operation of the transmission system shown in FIG. 1 will be explained.

The image digital data inputted from the input terminal 101 in FIG.
The signal is input to a signal processing section that uses the AX method and a signal processing section that uses only the MIN-MAX method. The signal processing unit has a frame memory 10, calculates the difference value between the decoded value of the previous frame and the current frame using a subtracter l, and sends the obtained value to an inter-frame maximum value detection unit 2 and an inter-frame minimum value detection unit. 3
, a timing adjustment section 4, an inter-frame division value conversion section 5, and a switch 7. The re-encoded signal is decoded by the inter-frame division value inverse converter 128 and stored in the frame memory 1.
It is added to the output of 0 by adder 8. Furthermore, new pixel data is rewritten into the frame memory IO via the switch 9.

This decoding/rewriting operation updates the contents of the frame memory and makes it possible to match the contents with the frame memory on the receiving side. Through these signal processes, interframe difference DPCM and MIN-MAX encoding are performed.

The motion detection is performed by the motion detection section 6 and the interframe maximum value detection section 2. It is obtained by determining the difference between the inter-frame minimum value detectors 3 and comparing the obtained value with a threshold value. Increasing this threshold value improves transmission efficiency, but causes deterioration in image quality of moving images, jerkiness, etc. in reproduced images. On the other hand, if it is made smaller, image quality deterioration etc. will be improved, but the transmission efficiency will be reduced, so it is necessary to take both into account and set it to an appropriate value.

Next, signal processing using only the MIN-MAX method is performed by the maximum value detection unit 103. Minimum value detection unit 104. timing adjustment section 1051 division value conversion section 1069 division time inverse conversion section 131;
The signal is processed by a MIN-MAX encoder comprising a switch 11.

These two signal processing outputs are switched in units of blocks by the output of the motion detector 6. When the image is close to a still image, signal processing using frame difference DPCM and the MIN-MAX method is performed, and when the image is a moving image, signal processing using only the MIN-MAX method is performed using the switch 12. At the same time as this switching, the input to the frame memory IO is changed by the switch 9 to the frame difference DPCM, MI when moving images.
By switching from the N-MAX method decoded signal to the signal of the divided value inverse transformer 131 using only the MIN-MAX method, it is possible to rewrite the contents of the frame memory IO and prevent encoding errors from accumulating.

A p-s (parallel-serial) converter 13 converts the input parallel data into serial data, adds one bit of motion data for each block from the motion detector 6, and outputs the data. Below is a conventional example.

is processed and output in the same way.

Next, the operation of the receiving system shown in FIG. 2 will be explained.

The input terminal 121 in FIG. 2 receives the transmission data that has been highly efficiently encoded on the transmitting side described above. The synchronization signal in the input data is separated by the synchronization separator 122 and supplied to the timing control section 25 . This timing control section 25 determines the operation timing of each section based on the synchronization signal.

On the other hand, in the 5-p (serial-parallel) converter 20,
Convert input serial data to parallel data. The motion information is separated by the motion signal separation section 24.

Each pixel block data set as parallel data is sent to the maximum value latch circuit 126. The minimum value latch circuit 1271 is decoded by the divided value inverse converter 128.

In the case of a moving image, the switch 22 transfers the decoded signal to the scan converter 1 according to the output of the motion signal separator 24.
Direct human power to 29. At the time of a still image, the adder 21
It is added to the output of the frame memory 23 and input. The same signal as the scan converter 129 is input to the frame memory 23 . By this operation of the frame memory 23, the frame difference value sent during the still image is decoded into the original pixel data. Thereafter, processing is performed in the same manner as in the conventional example.

Here, it will be explained that the number of transmission bits is reduced by using the inter-frame difference DPCM & MIN-MAX method together.

If frame-to-frame differences in pixel data are calculated using redundancy in the time axis of images, the dynamic range of the obtained data decreases. The stronger the redundancy, that is, the more stationary, the stronger this tendency appears. According to the motion detection unit of this embodiment, the condition for determining a still image is a trade-off between the correlation in the time axis (the former) and the correlation in the two-dimensional space (the latter). In other words, when the correlation in the time axis (the former) is very strong, the correlation in the two-dimensional space (the latter) only needs to be moderate, and conversely, when the former is weak, the latter is very strong. It can be seen that the number of effective bits under this condition may be a very small value. Based on the above conditions, the required number of bits for the maximum and minimum values is
Further, the required number of bits for the division value conversion section is determined based on the threshold value of the motion detection section.

As is clear from the above explanation, the interframe difference DPCM
When the MIN-MAX method and MIN-MAX method are used together, the data compression rate is greatly improved. For example, original data n in each pixel block =
8. l=m=3. In stationary mode n=3. = 2, the original data in each pixel block is (8X3X3=
)72 bits, transmission data is (3X2+2X3X3=)
24 bits, resulting in a data compression rate of 1/3.

In the above-mentioned image information transmission system, when the amount of information is small, such as when the image is a still image, the compression rate is increased, and when the image is a moving image, the compression rate is adjusted adaptively to the normal compression rate. Transmission efficiency can be improved without transmitting.

In the above embodiment, only the case of transmitting raster scanned image data was described, but when transmitting image information, regardless of the signal form of the original signal,
The present invention is applicable. In this case, the pixel block dividing circuit 102. It is only necessary to appropriately change the configuration of the scan converter section 129 and the like.

〔Effect of the invention〕

As explained above, according to the present invention, redundancy in the time direction of image information is removed, and high-quality image information is efficiently processed (
A method for transmitting image information that can be transmitted can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the transmitting side of an image information transmission system as an embodiment of the present invention; FIG. 2 is a schematic configuration diagram of the receiving side of the image information transmission system as an embodiment of the present invention; Figure 4 is a schematic diagram of the transmitting side of an image information transmission system according to the prior art; Figure 4 is a diagram showing how all image data is divided into pixel block groups; Figure 5 is a diagram showing the data arrangement of each pixel block; Figure 6 (a) is a diagram showing the conversion characteristics of the division value conversion unit in Figure 3, Figure 6 (b) is a diagram showing the conversion characteristics of the division value inverse conversion unit in Figure 8, and Figure 7 is a diagram showing the transmission characteristics. FIG. 8 is a diagram illustrating a schematic configuration of the receiving side corresponding to the transmitting side of the image information transmission system shown in FIG. 3. l・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・Listening songs/amount subtractor 2・・・・・・・・・・・・・・・・・・・
...... Inter-frame maximum value detection unit 3...
...... Inter-frame minimum value detection section 4.1
05... ・Inter-song timing adjustment section 5
・・・・・・・・・・・・・・・・・・・・・・・・・
Inter-frame division value conversion unit 6...
... Between songs...Motion detection sections 7, 9. 11. 12
・・・・・・・・・ Listen ・・Track switch 8・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
...... Song interval... Pause/pause adder 1
0 ・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Frame memory 1
3・・・・・・・・・・・・・・・・・・・・・・・・
・・Parallel-serial converter timing control section Pixel block division circuit Maximum value detection section Minimum value detection section
・・・・・・・・・・・・・・・・・・・・・・・・Division value conversion section・・・・・・・・・・・・・・・・・・・・・
・・・・・・Inter-frame division value inverse conversion Partial division value inverse conversion unit 14 ・・・・・・・・・・・・・・・・・・・・・
...02 03 04 06 28 31 1=30

Claims (1)

[Scope of Claims] A method for transmitting an image information signal in which one screen is made up of a plurality of pixel data, wherein the one screen of the plurality of pixel data is divided into a plurality of pixels for each predetermined number of pixel data. For each pixel block, it is determined whether the pixel block belongs to a video area or a still image area in the screen, and based on the determination result, the pixel data in the pixel block that belongs to the video area is divided into blocks. Encode and transmit based on a first encoding method using only pixel data within the same pixel block,
An image characterized in that pixel data in a pixel block belonging to a still image area is encoded and transmitted based on a second encoding method using pixel data in the same pixel block and pixel data in other pixel blocks. Information transmission method.