High efficiency technique for coding a digital video signal

Claim 2

A high efficiency coding apparatus for coding digital video data in a block format allowing compression of the video data, each block data including digital video data representing a three dimensional group of picture elements, said coding apparatus being characterised in that it comprises first detecting means (33) for detecting a maximum value of the digital video data of said three dimensional group of picture elements in said block; second detecting means (34) for detecting a minimum value of the digital video data of said three dimensional group of picture elements in said block; means (37, 38) for generating dynamic range information of the block from said maximum and minimum values; means (51) for subtracting said minimum value from each of the digital video data to generate modified digital video data; movement discriminating means (3) for discriminating the existence of the movement in each block and generating discriminating code; means (4) for encoding said modified digital data with the digitized bit number smaller than that of said modified digital data, said encoding means (4) being controlled by said discriminating code; and transmitting means (5) for transmitting tne output of said encoding means and an additional code per block formed of said discriminating code and at least two of said maximum value, minimum value, and a signal based on said dynamic range information.

Claim 3

A high efficiency coding apparatus according to claim 1, wherein said encoding means (4) is arranged to encode the modified digital data of one video field when said discriminating code indicates that no movement exists in said block.

Claim 4

A high efficiency coding apparatus according to claim 1 or 2, wherein said encoding means (4) includes averaging means for averaging the digital data of plural video fields and the output of said averaging means being encoded when said discriminating code indicates that no movement exists among said plural video fields.

Claim 5

A high efficiency coding apparatus according to claim 1,2 or 3 wherein said movement discriminating means (3) includes: a level comparator (21) for comparing a digital data of a picture element in a first video field and digital data of a corresponding picture element in a second video field; absolute value generating means (22) which is, in use, supplied with the output of said level comparator (21) and generates the absolute value of said output; comparator means (23) for comparing the output of said absolute value generating means (22) with a reference value; and discriminating means (26) for discriminating the output of said comparator means.

Claim 6

A decoding apparatus for decoding data transmitted by a coding apparatus for coding digital video data in a block format allowing compression of the video data representing a three dimensional group of picture elements and having first detecting means for detecting a maximum value of the digital video data of said picture elements in said block, second detecting means for detecting a minimum value of the digital video data of said picture elements in said block, means for generating dynamic range information of the block from said maximum and minimum values, means for subtracting said minimum value from each of the digital video data to generate modified digital video data, movement discriminating means for discriminating the existence of the movement in each block and generating discriminating code, means for encoding said modified digital data with the digitized bit number smaller than that of said modified digital data, said encoding means being controlled by said discriminating code, and transmitting means for transmitting the output of said encoding means and an additional code per block formed of said discriminating code and at least two of said maximum value, minimum value, and a signal based on said dynamic range information, said decoding apparatus comprising: separating means (62) for separating said discriminating code from said transmitted data; means for regenerating said minimum value from said additional code; decoding means (63) supplied with said discriminating code and said encoded data for decoding the encoded data to generate said modified data; and adder means for adding the minimum value to each of the modified data from said decoding means.

Claim 7

A decoding apparatus for decoding data transmitted by a coding apparatus for coding digital video data in a block format allowing compression of the video data representing a three dimensional group of picture elements and having first detecting means for detecting a maximum value of the digital video data of said picture elements in said block, second detecting means for detecting a minimum value of the digital video data of said picture elements in said block, means for generating dynamic range information of the block from said maximum and minimum values, means for subtracting said minimum value from each of the digital video data to generate modified digital video data, movement discriminating means for discriminating the existence of the movement in each block and generating discriminating code, means for encoding said modified digital data with the digitized bit number smaller than that of said modified digital data, said encoding means being controlled by said discriminating code, and transmitting means for transmitting the output of said encoding means and an additional code per block formed of said discriminating code and at least two of said maximum value, minimum value, and a signal based on said dynamic range information, said decoding apparatus comprising: separating means (62) for separating said discriminating code from said transmitted data; means for regenerating said minimum value from said additional code; decoding means (63) supplied with said discriminating code and said encoded data for decoding the encoded data to generate said modified data; and adder means for adding the minimum value to each of the modified data from said decoding means.

Claim 8

A decoding apparatus according to claim 5, wherein said decoding means includes: first and second gate means (123, 128) to which, in use, said transmitted data is supplied and to which said discriminating code is also supplied as a control signal; first and second decoders (125, 130) connected to said first and second gate means (123, 128), respectively; and combining means (131) for combining the outputs of said first and second decoders.

Claim 9

A decoding apparatus according to claim 6, wherein said first decoder (125) is arranged so as to generate the same decoded data for the corresponding picture elements in plural video fields.

Claim 10

A decoding apparatus according to claim 7, wherein said first decoder includes filtering means (127) which in use is made operative while the digital video data of picture elements in the beginning field of the block is generated.

Claim 11

A decoding apparatus according to claim 8, wherein said filtering means is an averaging circuit (127) for averaging the digital video data of picture elements in the beginning field of the block and digital video data of the corresponding picture elements in the preceding field to said beginning field of the block.