JP3146331B2 - Pixel data compression and playback method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for compressing and reproducing pixel data for reducing transmission and storage capacity in a videophone or the like.

[0002]

2. Description of the Related Art Conventionally, pixel data is compressed and reproduced using a complicated technique.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to easily compress pixel data in real time using human visual ambiguity (insensitive to coarse changes and sensitive to fine changes).
Another object of the present invention is to provide an economical pixel data compression / reproduction method capable of reducing transmission and storage contents.

[0004]

The structure of the present invention is as follows. (1) The pixel data is divided into upper bits and lower bits, and when the upper bits of the currently input pixel data are different from the upper bits of the previous pixel data during compression, "1" is added to the upper bits to add one bit. If the upper bits of the currently input pixel data are the same as the previous upper bits, “0” is added to the lower bits of the current pixel data to form one piece of compressed pixel data. In this manner, two consecutive pieces of compressed pixel data which have been subjected to the compression processing are configured as one set of transmission data which is divided up and down. At the time of reproduction, one set of input transmission data is divided into an upper bit portion and a lower bit portion. When it is detected that these bits have "1" added during compression, the remaining bits in this bit are the upper bits of the pixel data. When a predetermined lower bit is added to the upper bit to form a set of pixel data, and when it is detected that the bit portion has "0" added at the time of compression, the remaining bit portion of the bit portion is detected. The bits are determined as the lower bits of the pixel data, and the upper bits of the pixel data reproduced earlier and the lower bits of this time are combined to form one set of pixel data, thereby forming two sets of transmission data. And a pixel data compression and reproduction method for reproducing as pixel data. (2) At the time of reproduction, a set of input transmission data is latched as an upper bit portion and a lower bit portion, and when it is detected that these bit portions have "1" added at the time of compression, the remaining bits of the bit portion are detected. Is determined to be the upper bit of the pixel data, and a lower bit is added by adding a predetermined lower bit by comparing the upper bit with the previous upper bit.
The method for compressing and reproducing pixel data according to item 1, wherein the pixel data is a set of pixel data.

[0005]

FIG. 1 is a flow chart of pixel data compression showing one embodiment of the present invention. FIG. 2 is a flowchart of pixel data reproduction according to an embodiment of the present invention. FIG. 3 shows data of 64 gradations in which pixel data is composed of 6 bits. FIG. 4 is a system diagram of a telephone with a video camera and a television monitor.
1 is a video camera, 2 is an analog-digital (A /
D) a converter, 3 a digital-analog (D / A) converter, 4 a television monitor, 5 a control unit, 6 a storage unit, 7 a modem, and 8 a telephone circuit.

The video signal from the video camera shown in FIG.
The data is converted into 6-bit pixel data by the D converter 2.
A series of pixels, for example, the case where each pixel when the pixel A ₀ to A _n of one scanning line is composed of 6 bits shown in FIG. Next, the operation of compressing a video signal will be described with reference to FIG.

[0007] The video signal from the video camera 1 is converted by the A / D converter 2 to be pixel data for every 6 bits. When the first 6 bits of pixel data A ₀ are input to the control unit 5, “1” is added to the upper 3 bits “D ₀₅ , D ₀₄ , D ₀₃ ” of the pixel data D _{05 to} D _00. 4-bit data “1, D ₀₅ , D ₀₄ , D ₀₃ ”
Are latched as odd-numbered data. Next pixel data A
Upper 3 bits of 1 when a is input to the control unit 5 pixel data _{A1 "D 15, D 14,} D 13" is the last pixel data A
Upper 3 bits of _{0 "D 05, D 04,} D 03" to if there is a change _{"D 15, D 14, D} 13" to 4-bit data obtained by adding _{"1""1, D 15} , D 14, D ₁₃ "
If there is no change and the same, 4-bit data "0, D ₁₂ , D
₁₁ , D ₁₀ ″ are latched as even-numbered data. In this way, the 8-bit transmission data (1, D ₀₅ , D ₀₄ , D
₀₃ , 0, D ₁₂ , D ₁₁ , D ₁₀ ) and output them to the storage unit 6 or the like.

Next, the pixel data A ₂ is input to the control unit 5. The upper three bits “D ₂₅ ,
If D ₂₄ and D ₂₃ are the same with no change in the upper 3 bits of the previous pixel data A ₁ , “0” is added again and “0,
D _22, "latched as the odd data. Next, the control unit 5 pixel data _{A 3} is input to the upper 3 bits of the pixel data _{A 3" D 21, D 20} D 35, D 34, D
₃₃ ", in turn there is a change to the previous upper 3 bits of the pixel data _{A 2} on the upper 3 bits""obtained by _{adding" 1 1, D 35, D} 34, the even-numbered data _{D 33} " At this time, the odd-numbered data is
8-bit data “0, D ₂₂ , D ₂₁ , D ₂₀ , 1, D” in which even-numbered data are configured as lower 4 bits as bits
₃₅ , D ₃₄ , D ₃₃ ″ and output them to the storage unit 6 or the like. That is, since two sets of 6-bit pixel data can constitute one set of 8-bit transmission data, data compression is achieved.

Next, the reproducing operation will be described with reference to FIG. The 8-bit transmission data “DA ₇ , DA ₆ ,
_{DA 5, DA 4, DA 3} , DA 2, DA 1, DA 0, "
Are latched four bits at a time. It is determined whether the fourth bit is “1” or “0” every four bits. The 8-bit data “1, D ₀₅ , D ₀₄ ,
_Assuming that D ₀₃ , 0, D ₁₅ , D ₁₄ , and D ₁₃ ″ are input, the fourth upper 4 bits of the first 8-bit data are
Since the bit is “1”, the upper 3 bits of the 6-bit reproduction are set to “D ₀₅ , D ₀₄ , D ₀₃ ” which are the values of DA 6 to DA 4 of the input 8 bits. Next, since this time is the first input and there is no data of the previous upper bit, the upper bit data input this time is naturally larger than the previous upper bit data, and the lower 3 bits because of the change from the black level to the white level. Each is set to “0”. As a result, the first reproduced 6 bits are “D ₀₅ , D ₀₄ , D ₀₃ , 0,
0,0 "and converted by the D / A converter 3 to become a video signal.

[0010] Next, the fourth bit of the low order 4 bits latched in the first 8-bit data has a value of "0" are latched because it is "DA2, DA1, DA0"_{"D 12} , D ₁₁ , D _{10 ”} indicate the lower bits of the 6-bit data. Therefore, the upper bits previously latched are used as they are, and“ D ₀₅ , D ₀₄ , D ₀₃ , D ₁₂ , D _{12 ”
11} , D ₁₀ ″ is reproduced. The reproduced data is converted by the D / A converter 3 into a video signal and displayed on the television monitor 4. In this manner, the first input 8 bit data Is reproduced as two sets of 6-bit pixel data.

Next, since the fourth bit of the upper four bits of the second input 8-bit transmission data is "0", three bits excluding this "0" are the lower bits of the reproduced six bits. indicates that, reproduction 6-bit output for the upper 3 bits are same as the previous pixel data to be reproduced is _{"D 05, D 04, D} 03, D 22, D 21, D 20"
Becomes Since the fourth bit of the lower 4 bits of the second input 8-bit data is "1", this indicates that it is the upper bit of the reproduced 6 bits. Also, the upper bits “D ₀₅ , D ₀₄ , D ₀₃ ” of the previous pixel data
Is larger than the present upper bits “D ₃₅ , D ₃₄ , D ₃₃ ”, it indicates that the black level is changed from the white level, and the lower 3 bits of this time are each “1”, and as a result, the reproduction is performed. The 6-bit data is “D ₃₅ , D ₃₄ , D
₃₃ , 1, 1, 1 ". The 6-bit data is D /
The video signal is converted by the A converter 3 and displayed on the television monitor 4. Therefore, the second 8-bit transmission data is reproduced as two sets of 6-bit pixel data.

[0011]

As described above, the present invention can easily and inexpensively compress pixel data in real time and reduce transmission and storage capacity.

[Brief description of the drawings]

FIG. 1 is a flowchart of pixel data compression according to an embodiment of the present invention.

FIG. 2 is a flowchart of pixel data reproduction according to an embodiment of the present invention.

FIG. 3 is bit data of 64 gradations in which pixel data is composed of 6 bits.

FIG. 4 is a system diagram of a video camera and a telephone with a television monitor.

[Explanation of symbols]

 1 Video camera 2 A / D converter 3 D / A converter 4 TV monitor 5 Control unit 6 Storage unit 7 Modem 8 Telephone circuit

Claims (2)

(57) [Claims] 1. Pixel data is divided into an upper bit and a lower bit portion. At the time of compression, if the upper bit of the currently input pixel data is different from the upper bit of the previous pixel data, "1" is added to the upper bit. One piece of compressed pixel data. If the upper bit of the currently input pixel data is the same as the previous upper bit, add “0” to the lower bit of the current pixel data to form one piece of compressed pixel data. In this manner, two consecutive pieces of pixel data to be compressed which have been subjected to the compression processing as described above are configured as a set of transmission data which is sorted up and down.
A set of transmission data is latched as a high-order bit part and a low-order bit part, and these bit parts are added during compression.
When the presence of "1" is detected, the remaining bits of this bit portion are determined to be the upper bits of the pixel data, and a predetermined lower bit is added to the upper bits to form a set of pixel data. When it is detected that the bit portion has "0" added at the time of compression, the remaining bits of this bit portion are determined to be the lower bits of the pixel data, and the upper bits of the pixel data reproduced before this are A method of compressing and reproducing pixel data, comprising combining one set of pixel data by combining lower bits to reproduce one set of transmission data as two sets of pixel data. 2. During reproduction, a set of input transmission data is latched as an upper bit portion and a lower bit portion,
When it is detected that these bits have "1" added at the time of compression, the remaining bits of this bit are determined to be the upper bits of the pixel data, and the upper bits of the previous bit are compared with the previous bits to determine the size in advance. 2. The pixel data compression / reproduction method according to claim 1, wherein the determined lower bits are added to form a set of pixel data.