JPH01213088A - Picture encoding/transmitting method - Google Patents

Abstract

PURPOSE:To prevent the deterioration of quality by reducing the number of devisions of the picture elements of a head frame less than the standard number of the picture elements, and allotting them to the number of head picture elements, and encoding and transmitting them, and interpolating the decoded data of the head frame by the standard number of the picture elements before the encoding of a second frame. CONSTITUTION:A picture input signal is sent to a differential encoding/decoding part 4a by a camera 2a, and is converted by an A/D converting part 41, and is stored in an input frame memory 42. The input signal of the head frame is sent to a sampling part, and is divided into the number of the picture elements less than the standard number of the picture elements, and is stored temporarily in an input buffer. b AVQ divides the sampled input signal into blocks, and turns it into a vector input signal, and selects the most approximate pattern vector, and transmits the code book index of it to a transmission line. Besides, the decoded data is sent from the AVQ to an interpolating part, and the interpolating part interpolates the decoded data of the head frame in the standard number of the picture element by giving the arithmetic mean of right and left picture elements or top and bottom picture elements to the omitted picture elements.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image encoding and transmitting method, particularly to an improvement of an image encoding and transmitting method for video conferences, video telephones, and the like.

[Prior Art] In general, image transmission used for video conferences, video telephone calls, etc. involves a huge amount of image information, but due to line speed and transmission cost, etc. Compression encoding methods that reduce (compress) the amount of data have been put into practical use.

Among these, as a method for compressing the amount of information, an inter-frame difference method in which the correlation between mutually adjacent image information is encoded based on /+:Llt has been widely put into practical use as an efficient method.

A conventional image encoding method will be described below with reference to the drawings.

FIG. 4 shows a block configuration of an image transmission apparatus to which a conventional inter-frame differential encoding method is applied.

As shown in FIG. 4, image transmission devices (1a) and (1b) to which the conventional interframe differential encoding method is applied are connected via a bidirectional line, and the image transmission bags ff(la),
(1b) respectively have cameras (2a), (2b), received image monitors (3a), (3b), and differential encoding/decoding devices (4a), (4b).

Further, the differential encoding/decoding device (4a), (4b)
is an encoding device u that performs encoding and decoding by paying attention to the correlation between adjacent frames of image information;
What is the change 1i from the image information before the frame? ] Encoding and decoding to generate encoded information and decoded information.

Next, the operation will be explained.

First, the image information '7μ (Sl) is read frame by frame from the camera (2a), and the differential initial encoding/decoding device (4a)
is man-powered.

Since the image information (Sl) of the first frame does not have information from the previous frame, intra-frame encoding is performed using the correlation between adjacent pixels in the same frame, and it is transmitted as encoded information (S2). be done.

Next, the image information (Sl) of the second and subsequent frames is converted into encoded information (S2) by the differential encoding/decoding device (4a) based on the current input frame image information and the previous frame image information.
is generated, and the encoded information (S2) is transmitted to the image transmission device (1b) of the receiving section.

The differential encoding/decoding device (4b) of the image transmission device (]b) of the receiving section receives and decodes the encoded information (S2), and reproduces reproduction information (S3) based on the decoded information. )
generate.

The reproduction information (S3) is then displayed on the received image monitor (3b).
) will be displayed.

As described above, encoded information is generated and transmitted based on the correlation between adjacent frames, so when transmitting multiple images, the amount of information per image can be reduced compared to the intraframe encoding method. , video transmission becomes 11 functions.

[Problems to be Solved by the Invention] As described in -1- below, in the conventional image coding transmission method, the coding information m of the first frame is encoded within the frame.
The problem is that the amount of information in the second and subsequent frames that undergo inter-frame differential encoding is significantly larger, and the transmission time of the first frame is 10 to 40 times longer than the transmission time of other frames.

In order to solve the two-leg problem, the image encoder transmission method according to the present invention significantly reduces the amount of encoded information on the first screen,
1] The objective is to obtain an image encoding and transmission method that reduces the transmission time of the first leading frame of the first screen.

[Means for Solving the Problems] -1- What is the image according to the present invention in order to achieve the above object? n
The encoding method is to reduce the number of pixel divisions of the first frame to the number of standard pixels and divide it into the number of first pixels; By performing numerical interpolation, from the second frame onward, inter-frame differential encoding of the reference number of pixels is performed.

[Operation] As described above, according to the present invention, the number of pixel divisions in the first frame is reduced from the reference number of pixels and allocated to the number of first pixels, so that the number of divided pixels in the first frame is reduced compared to the reference number of pixels. Significantly reduce the amount of information required under No. 1 Law.

By interpolating the decoded data of the first frame using the reference number of pixels before encoding the second frame, it becomes possible to encode and transmit the images from the second frame onward without deteriorating their quality.

[Embodiment] Hereinafter, a preferred embodiment of the image encoding and transmission method according to the present invention will be described based on the drawings.

FIG. 1 shows a preferred block configuration of an image encoding and transmitting apparatus to which the method of the present invention is applied.

As shown in the figure, the features of the present invention include a sub-sampling section that performs sub-sampling of input pixels before intra-frame encoding of the first frame to make the number of pixels smaller than the reference number of pixels; This is an interpolation unit that decodes the decoded data of a frame and interpolates it to the reference number of pixels before outputting it to the frame memory.

First, the transmission of the image encoded transmission bag f+&(Ia) will be explained.

The camera (2a) reads the image input signal into the differential encoding/decoding section (4a) and sends it out.

And the difference? The image input signal is converted into a digital signal by an analog/digital converter (hereinafter referred to as A/D converter) in the code 1 decoding unit (4a), and is stored frame by frame in the input frame memory. .

First, the current input frame or the first frame (first frame)
The case will be explained below.

The input signal of the first frame is sent to the sub-sampling section, and the input signal of the first frame is sent to the sub-sampling section, and the input signal is
/2) and temporarily stored in a manual buffer.

Then, AVQ divides the input signal of the sampled first frame into blocks and converts it into a vector input signal.
The most similar pattern vector is selected from a group of pattern vectors stored in the VQ food book, and the codebook index of the pattern vector is sent to the transmission line via the transmission line encoder.

Further, decoded data is sent from the AVQ to an interpolation unit.

Then, as shown in Figure 2, the interpolation unit interpolates the decoded data of the first frame to the reference number of pixels by giving the arithmetic average of the left and right or top and bottom pixels to the thinned out pixels. .

Then, in the interpolation unit, the decoded data of the interpolated first frame is stored in the previous frame memory (previous FM) as −H, +
i will be remembered.

Next, the image input signal of the second frame is subjected to A/D conversion, stored in a manual frame memory, and sent as a vector input signal to the distortion calculation unit and AVQ in units of blocks.

After that, the distortion calculation unit stores - in the previous frame memory (previous FM).
Normal movement by comparison with stored decoded data?
Vector quantization including IIi compensation is performed.

Further, switching of the write address of the previous FM and the current FM is performed alternately using the FM address CTR.

On the other hand, reception will be explained.

First, reproduction of the encoded information of the first frame (first frame) will be explained.

Via the transmission line? ] Upon receiving the encoded information, the encoded information is input to the AVQ via the transmission line decoder.

Then, after vector decoding is performed in the AVQ,
The decoded data is input manually to the interpolation section.

Next, the interpolation unit interpolates it to the reference pixel number and inputs it to the previous FM, as in the case of transmission described above.

The received information from the second frame onward is reproduced in the same manner as in the conventional vector decoding method.

In the above embodiment, the pixel thinning method of the first frame is performed by sub-sampling, and the interpolation method of the interpolation section is an arithmetic average of the left and right or top and bottom pixels. Similar effects can be obtained even if other thinning methods and interpolation methods, such as performing interpolation through a filter with a reciprocal number of the filter, are applied.

[Effects of the Invention] - As explained above, the image encoding and transmission method according to the present invention assigns the number of divided pixels of the first frame to the number of first pixels that is reduced by the reference number of pixels, and performs encoding and transmission. , second
Since the decoded data of the first frame is interpolated with the reference pixel number and temporarily stored before inter-frame difference encoding of the frame, the amount of encoded information of the first frame can be significantly reduced, and the transmission time of the first frame can be shortened. At the same time, the quality of images after the second frame can be encoded and transmitted without deterioration.

[Brief explanation of the drawing]

Is Figure 1 an image related to the present invention? An image using the No. 1 method? FIG. 2 is an explanatory diagram of interpolation of decoded data of the first frame, and FIG. 3 is an explanatory diagram of a conventional image encoding transmission method. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent: Patent attorney Masu Oiwa (2 others)

Claims (1)

[Claims] (1) A preprocessing step of reading image information, A/D converting it, dividing it into a standard number of pixels, and generating image input data; and intra-frame encoding of the image input data of the first frame to generate encoded data. and an intra-frame encoding step of decoding the encoded data to generate decoded data; an inter-frame differential encoding step of performing encoding to generate encoded data and also generating the decoded data; a transmitting step of sequentially transmitting the encoded data; and a step of receiving and decoding the encoded data. In the image encoding transmission method, the preprocessing step allocates the number of pixel divisions of the first frame to a number of first pixels that is reduced from the reference number of pixels, and the interframe difference encoding step includes: , includes an interpolation step of interpolating the decoded data of the first frame to the reference number of pixels before interframe difference encoding of the second frame, and reduces the amount of encoded data generated in the intraframe encoding step. Features of image encoding and transmission method.