JPH0730776A - Image information transmitting method - Google Patents

Abstract

PURPOSE:To suppress gradation degradation in the case of digital image transmission. CONSTITUTION:There is one kind of a unique word UW and it is defined as '00' (which is a 16-adic description, 'FF' is available as well) and shared for a vertical synchronizing signal a horizontal synchronizing signal. The next data of this unique word UW are a synchronizing signal identification code expressing whether it is the vertical synchronizing signal or the horizontal synchronizing signal, VU expresses the vertical synchronizing signal and HU expresses the horizontal synchronizing signal. In the case of 8-bit data, the VU is decided as '00000000' (full bit description) and the HU is decided as '00000001' (full bit description as well), for example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image information transmission method, and particularly to an image information transmission method capable of preventing gradation deterioration.

[0002]

2. Description of the Related Art When transmitting digital image information, not only image data representing the contents of an image but also a vertical synchronization signal,
The horizontal sync signal must also be transmitted. A unique word is used for transmitting such a synchronization signal, as disclosed in, for example, Japanese Patent Laid-Open No. 4-104664.

FIG. 1 shows a transmission frame format according to a conventional transmission method. VU indicates a unique word corresponding to a vertical synchronizing signal, and HU indicates a unique word corresponding to a horizontal synchronizing signal. For 8-bit data, these V
For U and HU, for example, "FF", "00" (both in hexadecimal notation)
Are assigned respectively. Therefore, "FF" is added to the image data.
Since "00" cannot be used, it is necessary to apply a limiter to the image data to convert "FF" into "FE" and "00" into "01".

[0004]

Due to the need to transmit the unique word in this way, there is a problem that 8-bit image data must be degraded from 256 gradations to 254 gradations. In the case of 8 bits, there is not much visual deterioration, but in the case of data compression into 6 bits and 4 bits as in satellite communication, the deterioration of 2 gradations has a great visual impact.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide an image information transmission method in which deterioration of gradation is suppressed by using one kind of unique word. .

[0006]

FIG. 2 shows the format of a transmission frame according to the method of the present invention. There is one unique word UW, which is "00" (may be "FF") and is commonly used for the vertical synchronizing signal and the horizontal synchronizing signal. The data next to the unique word UW is a sync signal identification code that indicates the vertical sync signal and the horizontal sync signal, where VU is the vertical sync signal and HU is the horizontal sync signal. For 8-bit data, for example, VU is "00000000" (all bit notation),
HU is defined as "00000001" (also all bit notation).

[0007]

When the image information of such a format is transmitted, the vertical synchronizing signal and the horizontal synchronizing signal can be reproduced by the data of 2 words. Further, since the unique word is one type of "00" (or "FF"), gradation deterioration is only one gradation, which is improved compared to the conventional deterioration of two gradations.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 3 is a block diagram of the transmission device. An analog image signal obtained from a video camera (not shown) or the like is input to the A / D converter 1, the control unit 3, and the code generation circuit 6. The A / D converter 1 extracts only the video-related portion of the image signal, converts it into 8-bit image data, and supplies it to the limiter 2. The limiter 2 functions only to convert “00” in the input from the A / D converter 1 into “01”. The output of the limiter 2 is input to the selector 4. On the other hand, the code generation circuit 6 extracts the vertical synchronizing signal and the horizontal synchronizing signal from the image signal, outputs UW = “00” at those timings, and then outputs “00000000” for the vertical synchronizing signal and the horizontal synchronizing signal. In this case, "00000001" is output for each.

The control unit 3 gives the selector 4 a selection signal for selecting the unique word UW, the synchronization signal identification codes VU, HU and the image data by using the vertical synchronization signal and the horizontal synchronization signal of the image signal. Then, the selector 4 outputs a digital image signal having a format as shown in FIG. 2 whose time axis is substantially the same as that of the analog image signal. This digital image signal is output to the transmission line via the transmission line interface unit 5.

FIG. 4 shows a receiver. The image signal of the data from the transmitter is input to the transmission path interface section 7 via the transmission path, and from there, is input to the unique word (UW) detection section 8, the code determination section 9 and the separation section 10. When the UW detection unit 8 detects the UW from the input data, the detection information is input to the code determination unit 9. Upon receiving this detection information, the code determination unit 9 identifies “00000000” and “00000001” as VU and HU, respectively, assuming that the next data is the synchronization signal identification code, and supplies these identification information to the separation unit 10. The code determining unit 9 does not determine that VU “00000000” is UW or HU “00000001” is image data. The separation unit 10 separates the image data from the UW and VU / HU according to this input, and the former is D / A.
The latter is input to the converter 11 and the latter is input to the D / A converter 12.

Both data are converted into analog signals by the D / A converters 11 and 12, and both are input to the synchronizing signal adding section 13, where the pulse signal output from the D / A converter 12 is the vertical synchronizing signal, It is added to the analog image data output from the D / A converter 11 as a horizontal synchronizing signal and output to a monitor (not shown).

FIG. 5 shows another embodiment of the transmission frame format. In the above embodiment, the sync signal identification code of 8
Only the LSB is significant among the bits, but in the present embodiment, the higher 7 bits are also given meaning. That is, the number of bytes of code information inserted between the sync signal identification code and the image data is represented by 7 to 1 bits of the sync signal identification code. If these 7 bits are "0000000", there is no insertion code and "0000001"
, "1 word (C1 only)," 0000010 ", 2 words (C1, C2). This code can optionally be used for information that is desired to be sent with the image.

[0013]

According to the present invention as described above, since one gradation is only sacrificed due to the unique word representing the synchronization signal, gradation deterioration can be suppressed to a minimum, and an image with a small number of bits can be obtained. An excellent effect of improving image quality in transmission can be obtained. Further, the embodiment shown in FIG. 5 has an advantage that various information can be transmitted as codes C1, C2 ... Cn.

[Brief description of drawings]

FIG. 1 is a transmission frame format diagram in a conventional transmission method.

FIG. 2 is a transmission frame format diagram in the transmission method of the present invention.

FIG. 3 is a block diagram of a transmission device.

FIG. 4 is a block diagram of a receiving device.

FIG. 5 is a transmission frame format diagram in another embodiment of the present invention.

[Explanation of symbols]

 1 limiter 3 control unit 4 selector 6 code generation circuit 8 UW detection unit 9 code determination unit 10 separation unit 13 sync signal addition unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirotaka Nishida Inventor Hirotaka Nishida 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Fujitsu Limited (72) Inventor Kateru Nakamura 1015 Kamedotaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture Fujitsu Limited

Claims (1)

[Claims] 1. A method of transmitting digital image information including a plurality of types of synchronization signals and image data, wherein one type of unique word to be associated with the synchronization signal and a timing associated with each unique word are transmitted. A method for transmitting image information, characterized by transmitting the information including a synchronization signal identification code.