Adaptive type compression method for compressing a color image by imparting predetermined variable-length codes to combinations of quantized values based upon quantized prediction error components

Claim 2

An adaptive type compression method for compressing a color image comprising the steps of: (i) forming a plurality of blocks of picture elements, said picture elements each being represented by a plurality of color image components separated from a color image signal, each said block of picture elements comprising two adjacent picture elements,

Claim 3

(ii) obtaining sum components and difference components for each block using said color image components representing the two picture elements of each block,

Claim 4

(ii) obtaining sum components and difference components for each block using said color image components representing the two picture elements of each block,

Claim 5

(iii) transforming said sum components and said difference components of each two adjacent blocks into predication error components for each block,

Claim 6

(iii) transforming said sum components and said difference components of each two adjacent blocks into predication error components for each block,

Claim 7

(iv) quantizing said prediction error components on the basis of a quantization characteristic selected from a plurality of predetermined quantization characteristics,

Claim 8

(iv) quantizing said prediction error components on the basis of a quantization characteristic selected from a plurality of predetermined quantization characteristics,

Claim 9

(v) obtaining a plurality of combinations of quantized values based upon the quantized prediction error components for each block, and

Claim 10

(v) obtaining a plurality of combinations of quantized values based upon the quantized prediction error components for each block, and

Claim 11

(vi) imparting a predetermined variable-length code to each combination of quantized values.

Claim 12

(vi) imparting a predetermined variable-length code to each combination of quantized values.

Claim 13

An adaptive type compression method as defined in claim 1 further comprising the steps of: providing a buffer memory having a predetermined capacity, entering into said buffer memory said variable-length code imparted to each combination of quantized values of said prediction error components for each block at an input bit rate and reading out therefrom said variable-length code at a predetermined output bit rate asynchronously with the input bit rate to said buffer memory, and, after the variable-length codes for a plurality of predetermined blocks have been entered into said buffer memory, selecting a quantization characteristic from said plurality of predetermined quantization characteristics to be used for the quantization of the prediction error components for a next plurality of predetermined blocks on the basis of the amount of said variable-length codes remaining in said buffer memory.

Claim 14

An adaptive type compression method as defined in claim 2 further comprising the steps of: adding the code length of a variable-length code to an address counter when the variable-length code is entered into said buffer memory, and subtracting the code length of a variable-length code from the address counter when the variable-length code is read out from said buffer memory, dividing said buffer memory into a plurality of address spaces represented by address pointers L1, L2, . . . , Lp, and, after the variable-length codes of said plurality of predetermined blocks have been entered into said buffer memory, selecting a quantization characteristic to be used for the quantization of the prediction error components for said next plurality of predetermined blocks by discriminating, based upon said address pointers L1, L2, . . . , Lp, the amount of said address spaces occupied by said variable-length codes remaining in said buffer memory.

Claim 15

An adaptive type compression method as defined in claim 2 further comprising the steps of providing an address pointer Ls at a predetermined point in the address space of said buffer memory, and starting to read out said variable-length codes from said buffer memory when said variable-length codes entered into said buffer memory reach said address pointer Ls.