Control system for encoding image

Claim 2

An image encoding control system as claimed in claim 1, wherein said predetermined number of variable-length code words is smaller than a number of transform coefficients related to pixels in each block.

Claim 3

An image encoding control system as claimed in claim 1, wherein said variable-length code words are two-dimensional variable-length codes, wherein said code control means comprises: count means for counting a number of effective coefficients out of said transform coefficients for each block; comparing means for comparing the number of effective coefficients counted by said count means with a predetermined threshold value; and select means, provided between said orthogonal transform encoding means and said variable-length encoding means, for selecting said transform coefficients output by said orthogonal transform encoding means when the number of effective coefficients is equal to or smaller than said predetermined threshold value and for selecting "0" when the number of effective coefficients exceeds said predetermined threshold value.

Claim 4

An image encoding control system as claimed in claim 3, wherein said predetermined threshold value is equal to said predetermined number of variable-length code words.

Claim 5

An image encoding control system as claimed in claim 3, wherein said variable-length control means comprises: count means for counting, for each block, a number of consecutive zeros out of said transform coefficients output by said code control means; and converting means for generating said variable-length code words from said number of consecutive zeros and said effective coefficients output by said code control means.

Claim 6

An image encoding control means as claimed in claim 5, wherein said converting means comprises: memory means for having, as an address, said number of consecutive zeros and said effective coefficients and for storing code words and code lengths corresponding to combinations of said number of consecutive zeros and said effective coefficients; and rotating means for generating aid variable-length code words from said said code words and code lengths.

Claim 7

An image encoding control means as claimed in claim 1, wherein said variable-length code words are run-length codes, and wherein said code control means comprises: count means for counting, for each block, a sum total of a number of effective coefficients out of said transform coefficients and a number of strings, each having consecutive zeros; comparing means for comparing the sum total counted by said count means with a predetermined threshold value; and select means, provided between said orthogonal transform encoding means and said variable-length encoding means, for selecting said transform coefficients output by said orthogonal transform encoding means when the number of effective coefficients is equal to or smaller than said predetermined threshold value and for selecting "0" when the number of effective coefficients exceeds said predetermined threshold value.

Claim 8

An image encoding control system as claimed in claim 7, wherein said predetermined threshold value is equal to said predetermined number of variable-length code words.

Claim 9

An image encoding control system as claimed in claim 7, wherein said variable-length encoding means comprises: count means for counting, for each block, a number of consecutive zeros out of said transform coefficients output by said code control means; select means for selecting, for each pixel, either the number of consecutive zeros counted by said count means or the effective coefficient output by said code control means; and converting means for generating said variable-length code words from the number of consecutive zeros or the effective coefficients selected by said select means for each pixel.

Claim 10

An image encoding control system as claimed in claim 9, wherein said converting means comprises: memory means for having a first table storing a code word and a code length corresponding to said number of consecutive zeros and for having a code word and a code length corresponding to the effective coefficient; and rotating means for generating said variable-length code output from said code word and said code length output by said memory means.

Claim 11

An image encoding control system as claimed in claim 1, wherein: each of said transform coefficients is a residual signal between input image signals related to blocks of two consecutive frames; and said image encoding control system comprises quantizing means for quantizing said residual signal and for outputting a quantization output corresponding to a corresponding one of said transform coefficients.

Claim 12

An image encoding control system as claimed in claim 11, further comprising: reverse quantizing means for reverse-quantizing, for each block, said transform coefficients supplied from said code control means and for generating a reverse-quantization output; frame memory means for storing the reverse-quantization output related to a block which precedes a block being processed by said quantization means by one block; adding means for adding the reverse-quantization output related to the block being processed and the reverse-quantization output related to the block preceding said block being processed by one block; and subtracting means for obtaining a difference between the input image signal related to the block being processed and the reverse-quantization output related to the block preceding the block being processed by one block and for generating said residual signal.

Claim 13

An image encoding control system as claimed in claim 12, further comprising select means for selecting either the reverse-quantization output from the frame memory means or "0" and for outputting selected data to said adding means.

Claim 14

An image encoding control as claimed in claim 12, wherein said variable-length code words are two-dimensional variable-length codes, wherein said code control means comprises: count means for counting, for each block, a number of effective coefficients out of said transform coefficients; comparing means for comparing the number of effective coefficients with a predetermined threshold value; and a selector for selecting said transform coefficients output by said orthogonal transform encoding means when said number of effective coefficients is equal to or smaller than said predetermined threshold value and for selecting "0" when said number of effective coefficients exceeds said predetermined threshold value, and wherein said select means selects "0" when said selector selects "0", and selects the reverse-quantization output from said frame memory means when said selector selects the transform coefficients from said orthogonal transform encoding means.

Claim 15

An image encoding control system as claimed in claim 12, wherein said variable-length code words are run-length codes, wherein said code control means comprises: count means for counting, for each block, a sum total of a number of effective coefficients out of said transform coefficients and a number of strings, each having consecutive zeros; comparing said sum total counted by said count means with a predetermined threshold value; and select means, provided between said orthogonal transform encoding means and said variable-length encoding means, for selecting the reverse-quantization output from said frame memory means when said sum total is equal to or smaller than said predetermined threshold value and for selecting "0" when said sum total exceeds said predetermined threshold value.

Claim 16

An image encoding control system as claimed in claim 12, wherein each of said blocks has n x n pixels (n is an arbitrary integer).

Claim 17

An image encoding control system as claimed in claim 1, further comprises: subtracting means for obtaining a difference between the input image signal being processed and the input image signal related to a block which precedes the block being processed by one block and for generating a residual signal supplied to said orthogonal transform encoding means; quantizing means for quantizing an orthogonal-transform-encoded residual signal output by said orthogonal transform encoding means and for generating a quantization output corresponding to said transform coefficients; reverse-quantizing means for reverse-quantizing, for each block, said transform coefficients output by said orthogonal transform encoding means and for generating a reverse-quantization output; reverse-orthogonal transform encoding means for reverse-orthogonally transforming said reverse-quantization output; adding means for adding a reverse-orthogonally transformed code output related to the block being processed and a reverse-orthogonally transformed code output related to the block which precedes the block being considered by one block; and frame memory means for storing an addition result from said adding means, said addition result read out from said frame memory means being a frame memory output supplied to said subtracting means.

Claim 18

An image encoding control system comprising: means for converting an analog image signal into a digital image signal; dividing means for dividing said digital image signals into 1 (1 is an arbitrary integer) input image signals by a time division, each of said 1 input image signals having a frequency lower than that of said digital image signal; 1 orthogonal transform encoding means, respectively provided for said 1 input image signals, for carrying out an orthogonal transform encoding for each block obtained by dividing one picture plane of each of input input image signals into a plurality of blocks, each of said plurality of blocks having transform coefficients related to said pixels; 1 code control means, respectively provided for said 1 orthogonal transform encoding means, for controlling said transform coefficients output by said 1 orthogonal transform encoding means so that a number of variable-length code words obtained for each block is equal to or less than a predetermined number of variable-length code words; 1 coefficient processing means, respectively provided for said 1 code control means, for generating, for each block, data defining a variable-length code output from said transform coefficients output by said 1 code control means; select means for selecting said data generated by said 1 coefficient processing means on a time-division base to thereby output a data string; converting means for generating said variable-length code output from said data contained in said data strings; and buffer memory means for temporarily storing said variable-length code output output by said converting means.

Claim 19

An image encoding control system as claimed in claim 18, wherein said data defining said variable-length code output includes effective coefficients out of said transform coefficients and a number of consecutive zeros contained in said transform coefficients.

Claim 20

An image encoding control system as claimed in claim 19, wherein said variable-length code words are two-dimensional variable-length codes; and wherein each of said 1 code control means comprises: count means for counting, for each block, a number of effective coefficients out of said transform coefficients; comparing means for comparing said number of effective coefficients with a predetermined threshold value; and select means, provided for said 1 orthogonal transform encoding means and said 1 code control means, for selecting said transform coefficients from said 1 orthogonal transform encoding means when said number of effective coefficients is equal to or smaller than said predetermined threshold value and for selecting "0" when said number of effective coefficients exceeds said predetermined threshold value.

Claim 21

An image encoding control system as claimed in claim 18, wherein said variable-length code words are run-length codes, and each of said 1 code control means comprises: count means for counting a sum total of a number of effective coefficients out of said transform coefficients and a number of strings, each having consecutive zeros; comparing means for comparing said sum total with a predetermined threshold value; and select means, provided between said 1 orthogonal transform encoding means and said 1 code control means, for selecting said transform coefficients from said 1 orthogonal transform encoding means when said sum total is equal to or smaller than said predetermined threshold value and for selecting "0" when said sum total exceeds said predetermined threshold value.

Claim 22

An image encoding control system as claimed in claim 20, wherein said predetermined threshold value is equal to said predetermined number of variable-length code words.

Claim 23

An image encoding control system as claimed in claim 21, wherein said predetermined threshold value is equal to said predetermined number of variable-length code words.

Claim 24

An image encoding control system as claimed in claim 18, wherein said converting means comprises: memory means for having, as an address, the number of consecutive zeros and said effective coefficients and for storing code words and code lengths thereof corresponding to combinations of said number of consecutive zeros and said effective coefficients; and rotating means for generating said variable-length code outputs from said code words and code length thereof output from said memory means.

Claim 25

An image encoding control system as claimed in claim 19, wherein said converting means comprises: memory means for having a first table storing a code word and a code length corresponding to said number of consecutive zeros and for having a code word and a code length corresponding to the effective coefficient; and rotating means for generating said variable-length code output from said code word and said code length output by said memory means.

Claim 26

An image encoding control system as claimed in claim 24, wherein said rotating means is used in common for a decoding side.

Claim 27

An image encoding control system as claimed in claim 25, wherein said rotating means is used in common for a decoding side.