JPH01144874A - Image processing device - Google Patents

Abstract

PURPOSE:To efficiently transmit high-definition image information by encoding then transmitting picture element data in a picture element block belonging to a moving image area by a first encoding system and encoding then transmitting picture element data in a picture element block belonging to a still image area by a second encoding system whose transmission efficiency is different than that of the former. CONSTITUTION:A moving is detected by obtaining the difference between a maximum value detection part 2 and a minimum value detection part 3 by means of a moving detection part 6 and by comparing thus obtained value with a threshold value. In case the image is close to a still picture, a signal processing using the inter-frame difference DPCM and MIN-MAX method is employed through a switcher 12, but in case the image is of a moving picture, a signal processing using the MIN-MAX method only is employed also through the switcher 12. As a result, the redundancy in the time direction of image information can be eliminated and high-definition image information can be transmitted efficiently.

Description

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

[Prior Art] Conventionally, 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, with specific reference to the drawings regarding this encoding,
I'll explain.

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.
The digital image data is digitized into n-bit data per sample. This 2a 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
In this case, 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 (L×m) 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, Dl,...
~ol114 indicates each pixel data. The image data output from the pixel block division circuit 102 is sent to the maximum value detection section 103. The signal is input to minimum value detection section 104 and timing adjustment section 105. As a result, among all the pixel data (Dl, +~01.) in each pixel block, those having the maximum value (D, , ) and those having the minimum value (Dln) are detected by the detection units 103 and 104, Output.

On the other hand, in the timing adjustment section 105, the maximum value detection section 103 and the minimum value detection section 104 perform DIllaX+DR.
All pixel data is delayed by the time necessary to detect IIn, 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, Dl, l+02□+03.
l+-, D■, l+ Dl, 2+ ”°+ DB,
2+ ””, Dl, (J-th, ++0°0a,
It is transmitted in the following order: tt-t+ + Dl, A"..., o,, l.

In this way, all pixel data (D8
．． ~D,,L), their maximum value ([1, □) and minimum value (Dmtn) are input to the division value conversion unit 106, and for each pixel data, the difference between DIIlaX and Dmln is
A bit division code (Δ1.1 to Δ1.L) is obtained by comparing the divided quantization level. 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), Δ1. ．． Hanibit no 2
Output as value sign. The division sign Δ gain of bits obtained in this way, Dmax and Dla of j and n bits
ln is each parallel-serial (P-5) converter 1
07. '107' and '107'' are converted into serial data, and the data selector 108 converts them into serial data as shown in FIG.
The figure 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 then a synchronization number 43 is added by a synchronization adding section 11G, and the signal is sent to a transmission path (for example, a magnetic recording/reproducing system such as a VTR) from an output terminal 111. . Here, the synchronization signal may be added for each pixel block or for each 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. A synchronization signal in the manually inputted transmission data is separated by a synchronization separation section 122 and supplied to a 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 DIlIaX+'1mIn of the aforementioned transmission data and the code Δ1. ．． It is divided into. These are respectively serial-to-parallel (S-P) converters 125.
125', it is converted into parallel data. Maximum value data Dmax and minimum value data On+In in each pixel block converted into parallel data by the sp converter 125
are latched by latch circuits 126 and 127, respectively,
Latched maximum value data D□8 and minimum value data Dm
In is output to the divided value inverse transform unit 128, respectively. On the other hand, the division code Δ for each pixel data in each pixel block
1. ．． is the S-P converter 12 in a predetermined order as described above.
5' and supplied to the divided value inverse transformer 128.

FIG. 6(b) shows the division code Δ1. ．． and Dmax+Da+
From In to representative value data D'1 regarding the original pixel data. J
As shown in the figure, the representative value is set, for example, to the middle of each quantization level obtained by dividing DIllaX+DISIn into two. In this way, the n-bit representative value data (0"1.1~
D', , L) are output for each pixel block in the order described above. The scan converter unit 129 converts the output data of the divided value inverse converter 128 into an order corresponding to raster scanning, and outputs the converted image data to the output terminal 130 as decoded image data.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, correlations only in the two-dimensional space of images are utilized. 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.

Therefore, in view of the above 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 the Problems] The image information transmission method according to the present invention is a method for transmitting image information in which one screen is made up of a plurality of pixel data, and wherein The pixel data is divided into a plurality of pixel blocks for each predetermined number of pixel data, it is determined for each pixel block whether the pixel block belongs to a moving image area or a still image area in the screen, and based on the determination result, The pixel data in the pixel block belonging to the video area is encoded and transmitted based on the first encoding method, and the pixel data in the pixel block belonging to the still image area is transmitted based on the first encoding method. The data is encoded and transmitted based on a second encoding method different from the above.

[Function] As described above, by adaptively transmitting image information 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 division circuit 102, 2 is a maximum value detection unit that finds the maximum value of the output of the subtracter 1, and 3 is the same that finds the minimum value. a minimum value detection section; 4 is a timing adjustment section that adjusts the transmission time from the maximum value detection section 2 to the divided value conversion section 5; 6 is a movement that determines movement from the outputs of the maximum value detection section 2 and the minimum value detection section 3; Detection unit; 7 is a switch for switching the outputs of the respective units 2 and 3.5; 8 is an adder for adding the outputs of the divided value inverse conversion unit 128 and the frame memory IO; 9 is a manual addition to the frame memory IO. 11 is a maximum value detection unit 103. A switch for switching the outputs of the minimum value detection unit 1041 and the division value conversion unit 106; 12 is a switch for manually inputting the signal from either switch 7 or 11 to the P-5 converter 13; 13 is a switch from the switch 12; The p-s converter converts the signal from parallel to serial and adds the output of the motion detection section 6. 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 human power 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 converter 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; 24 is a motion signal from the output of the sp converter 20; 25 is a timing control unit that controls the timing of each circuit from the output of the synchronization separator 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 MAX method and a signal processing section that uses only the MIN-MAX method. The signal processing section has a frame memory 10, a subtracter 1 calculates the difference between the previous frame and the current frame, and the obtained value is sent to the maximum value detection section 2. Re-encoding is performed by a MIN-MAX method encoder comprising a minimum value detection section 3, a timing adjustment section 40, a division value conversion section 5, and a switch 7. The re-encoded signal is decoded by the division value inverse transformer 128 and added to the output of the frame memory IO by the adder 8. Furthermore, new pixel data is rewritten in 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 old N-MAX method encoding are performed.

Motion detection is obtained by calculating the difference between the maximum value detection section 2 and the minimum value detection section 3 using the motion detection section 6, 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 you make it smaller, the image quality will be poor.

Although the transmission efficiency is improved, the transmission efficiency is reduced, so it is necessary to take both into consideration and set 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 1059 Division value conversion section 106. 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 switch 9 switches the manual input to the frame memory 10 from the DPCM and MTN-MAX method decoding signals to the signals of the pixel block division circuit 102 during moving images.
The error accumulation value due to M) can be refreshed to the correct value.

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. Thereafter, the data is processed and output in the same manner as in the conventional example.

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 manually generated data is the synchronization part! 11122 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, a 5-P (serial-parallel) converter 20 converts input serial data into 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.
29 directly. 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 manually. 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 and the 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 still image, the more 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 CPCM
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. β=m=3 If n=3 and n=2 in stationary mode, the original data in each pixel block is (8X3X3=)72
The transmission data will be (3x2+2x3x3=)24 bits, and the data compression rate of the station will be obtained.

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.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain an image information transmission method that can remove temporal redundancy of image information and efficiently transmit high-quality image information.

[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. 1... Subtractor, 2.103... Maximum value detection section, 3.104... Minimum value detection section, 4.105... Timing adjustment section, 5.106... Division value conversion section, 6...Motion detection section, 7.9, 11.12...Switcher, 8...Adder, lO...Frame memory, 13...Parallel-serial converter, 14...Timing Control unit, 102... Pixel block division circuit, 128... Division value inverse conversion unit. Figure 4 Figure 5 G ζ ch Q

Claims (1)

[Claims] A method for transmitting image information in which one screen is composed of a plurality of pixel data, wherein the one screen of the plurality of pixel data is divided into a plurality of pixel blocks 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 The pixel data in the pixel block belonging to the still image area is encoded and transmitted based on a second encoding method that has a different transmission efficiency from the first encoding method. An image information transmission method characterized by: