JPH0670338A - Still picture transmitter - Google Patents

Abstract

PURPOSE:To code a still picture efficiently and to send the coded signal without separation of the picture into a chrominance component and a luminance component when the still picture is sent. CONSTITUTION:A read address generator 14 of a transmission section 1 generates an address to read picture data sequentially in the longitudinal direction of the picture while skipping one horizontal scanning period, the picture data read from a picture memory 12 are coded by a prediction difference coder 15 and the coded data are sent. A prediction difference decoding circuit 21 in a reception section 2 applies prediction difference decoding to the received picture data and the decoded picture data are written longitudinally for each horizontal scanning period by an address 201 of a write address generator 23 and the decoded picture data are read horizontally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for transmitting an image represented by a television signal, and more particularly to a still image transmitting device for transmitting a quantized still image.

[0002]

2. Description of the Related Art In a conventional still image transmission apparatus, a predictive differential encoding method is often used as a means for compressing the information amount of image data. In this predictive differential encoding method, image data is sequentially read in the horizontal direction, the value of the subsequent data is predicted from the value of the previous data and the amount of change, and the difference value between the predicted value and the value of the actual data is calculated. This is a method of converting into an unequal length code and transmitting. In order to apply this prediction difference encoding method to a color image, since there is a subcarrier component that represents a color component, the error between the predicted value and the actual value becomes large, and efficient encoding is performed. I can't do it. For this reason, a color image is separated into a luminance component and a color component before encoding, and the prediction difference encoding is separately performed for each component.

[0003]

In the conventional method in which a color image is separated into a luminance component and a color component, and prediction difference encoding is separately performed, the code data amount corresponding to the color component is larger than that in a monochrome image. There was a problem that transmission took time. In addition, there is a problem in that the transmission requires a means for synthesizing and separating the code of the luminance component and the code of the color component. The present invention has been made to solve such a problem, and an object thereof is to obtain a still image transmission apparatus that efficiently encodes and transmits a still image without separating it into a color component and a luminance component. And

[0004]

A still image transmitting apparatus of the present invention is an apparatus for storing, encoding and transmitting an image represented by a television signal, and reading out image data in a vertical direction by skipping every horizontal scanning period. The reading means and the coding means for performing the prediction difference coding on the image read by the reading means are provided.

A still image transmitting apparatus according to another invention of the present invention is a device for decoding received image data into a television signal, and decoding means for performing predictive differential decoding on the received image data. And a writing means for writing the image data obtained by the decoding means in the vertical direction by skipping every horizontal scanning period, and a reading means for reading out the image data decoded by the decoding means in the horizontal direction. It is a thing.

[0006]

According to the present invention, the image data is skipped every horizontal scanning period and read in the vertical direction to perform predictive differential encoding, and the decoded image data is skipped every horizontal scanning period in the vertical direction. The written image data and the decoded image data are read out in the horizontal direction.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 1 is a transmitter, and 2 is a receiver that receives image data from the transmitter 1 via a transmission line 3. Then, 11 in the transmitter 1 is a video signal 10
An analog / digital (A / D) converter for converting 1 into digital data 102, and 12 is this A / D converter 11
The image memory 13 stores the digital data 102 converted by the above, 13 is a write address generator for generating an address for writing the image data in one horizontal scanning period, and 103 is an address signal from the write address generator 13. Reference numeral 14 is a read address generator for reading the image data written in the image memory 12 according to the address 104. The read address generator 14 is a read means for reading the image data in the vertical direction by skipping every horizontal scanning period. I am configuring. Reference numeral 15 is a predictive difference encoder for predictive difference encoding the image data 105 read from the image memory 12, and the predictive difference encoder 15 is a code for performing predictive difference encoding on the image read by the reading means. It constitutes the means of conversion.

Reference numeral 21 in the receiver 2 is a predictive difference decoding circuit for decoding the image data received from the transmission line 3, and the predictive difference decoding circuit 21 is a decoding means for performing predictive difference decoding on the received image data. Are configured. 22
Is an image memory for storing the image data decoded by the predictive difference decoding circuit 21, 23 is a write address generator for generating an address 201, and the write address generator 23 is the image data obtained by the decoding means. The writing means is configured so as to jump in every horizontal scanning period and write in the vertical direction. Reference numeral 24 is a read address generator for generating the address 202, and the read address generator 24 constitutes a reading means for reading out the image data decoded by the decoding means in the horizontal direction. A digital / analog (D / A) converter 25 converts the read image data 203 into a video signal 204 which is an analog signal.

FIG. 2 is a block diagram showing a configuration example of the write address generator 13 in FIG. In FIG. 2, 13-1 is a horizontal address counter, 13-2 is a carry signal 13-3 from the horizontal address counter 13-1.
Is a vertical address counter, 13-4 is a horizontal address, and 13-5 is a vertical address. FIG. 3 is a block diagram showing a configuration example of the read address generator 14 that generates addresses in the vertical direction of the image in FIG. This Figure 3
14-1 is a vertical address counter, 14-2 is a 1-bit counter which receives the carry output signal 14-4 from the vertical address counter 14-1, and 14-3 is a 1-bit counter 14-2. A horizontal address counter having the carry output signal 14-5 as an input, 14-6 a vertical address counter 14-1 and a 1-bit counter 1
The vertical address signal output from 4-2, the horizontal address signal 14-7 output from the horizontal address counter 14-3, 14-8 the count value output from the vertical address counter 14-1, and 14-9 the 1 It is a count value output from the bit counter 14-2. FIG. 4 is an explanatory diagram for explaining the operation of FIG. 3, and shows the relationship between the movement of the position on the image indicated by the vertical address and the horizontal address generated by the read address generator of FIG. 3 and the phase of the subcarrier signal. .

Next, the operation of the embodiment shown in FIG. 1 will be described with reference to FIGS. First, in the transmitter 1, the video signal 101 is input to the A / D converter 11 of the transmitter 1,
The video signal 101 is converted into digital data 102 and written in the image memory 12. This image memory 12
The address written to is the write address generator 1
3 is indicated by the address signal 103. As shown in FIG. 2, the write address generator 13 is composed of a horizontal address counter 13-1 and a vertical address counter 13-2. The horizontal address counter 13-1 outputs the address of image data in one horizontal scanning period. The address 13-4 is shown as a carry signal 13-3 at the end of one horizontal scanning period.
As a result, the vertical address counter 13-2 advances by one, and the vertical address 13 for writing the image data in the next horizontal scanning period is written.
-5 is shown.

The image data written in the image memory 12 in FIG. 1 is read according to the address 104 indicated by the read address generator 14. The read address generator 14 comprises a vertical address counter 14-1, a 1-bit counter 14-2 and a horizontal address counter 14-3 as shown in FIG. In FIG. 3, first, the vertical address counter 14-1 operates and the carry output signal 14-4 operates the 1-bit counter 14-2. The count value 14-8 output from the vertical address counter 14-1 and the count value 14-9 output from the 1-bit counter 14-2 are combined to form a vertical address signal 14-6. Here, the output of the 1-bit counter 14-2 is used as the least significant bit of the address. Next, the horizontal output counter 14-3 is operated by the carry output signal 14-5 of the 1-bit counter 14-2, and the count value becomes the horizontal address signal 14-7.

FIG. 4 shows the relationship between the movement of the position on the screen indicated by the vertical address and the horizontal address and the phase of the subcarrier signal. In FIG. 4, first, the position of I on the nth scanning line is shown, then the position of jump II is shown on the n + 2th scanning line, and then the position of III on the n + 4th scanning line. The address is skipped every horizontal scanning line. By doing this,
The same phase portion of the subcarrier signal can be read continuously.

Then, when the process goes all the way in the vertical direction, the 1-bit counter in the example of FIG. 3 moves, the position of IV on the (n + 1) th scanning line in FIG. 4 is shown, and then the position of V on the (n + 3) th scanning line. The address moves to the position, and then to the position of VI of the (n + 5) th scan line. When the vertical address has advanced, the horizontal address moves, and the position of VII of the nth scanning line is shown.
Next, the address advances such as the position of VIII of the (n + 2) th scanning line. In FIG. 1, the image memory 1
The image data 105 read from No. 2 is subjected to prediction difference encoding by the prediction difference encoder 15 and sent to the transmission line 3.

Next, in the receiving section 2, the data received from the transmission line 3 is decoded by the predictive difference decoding circuit 21 and written in the image memory 22. The address to be written is the address 201 generated by the write address generator 23.
Indicated by. This address is generated so as to be written in the same order as the read address generator 14 of the transmitter 1. Then, the image data 203 is read from the image memory 22 according to the address 202 generated by the read address generator 24. Here, the read address generator 24 generates an address like the write address generator 13 of the transmitter 1. The read image data 203 is converted into an analog signal by the D / A converter 25,
The video signal 204 is output.

[0015]

As described above, according to the present invention, the image data is skipped every horizontal scanning period to be read in the vertical direction to perform the prediction difference encoding, and the decoded image data is also transmitted horizontally. Since the image data that has been written in the vertical direction is skipped every scanning period and the decoded image data is read out in the horizontal direction, it is possible to perform transmission even if the influence of the subcarrier signal included in the color image is suppressed, so that efficient transmission is possible. It has the effect of being able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a write address generator in FIG.

3 is a block diagram showing a configuration example of a read address generator that generates addresses in the vertical direction of the image in FIG.

FIG. 4 is an explanatory diagram for explaining the operation of FIG.

[Explanation of symbols]

 1 Transmitter 2 Receiver 3 Transmission Line 14 Read Address Generator 15 Prediction Difference Encoding Circuit 21 Prediction Difference Decoding Circuit 23 Write Address Generator 24 Read Address Generator

Claims (2)

[Claims] 1. A device for storing, encoding and transmitting an image represented by a television signal, and reading means for reading image data in a vertical direction by skipping every horizontal scanning period, and an image read by the reading means. A still image transmission device, comprising: an encoding unit that performs predictive differential encoding. 2. An apparatus for decoding received image data into a television signal, comprising decoding means for performing predictive differential decoding on the received image data, and image data obtained by this decoding means. A still image transmission apparatus comprising: a writing unit that interleaves every horizontal scanning period and writes in the vertical direction; and a reading unit that reads out the image data decoded by the decoding unit in the horizontal direction.