Fuzzy-controlled coding method and apparatus therefor

A fuzzy-controlled coding method for coding successive image frames which each express at least one image and wherein a quantization step size of predetermined block units of a frame is controlled so as to be quantized and at least one of transferred and recorded, said method comprising:

• a local decoding step for detecting a degree of motion between a predetermined block unit of a previous frame and a predetermined block unit of a current frame, and for extracting an estimated block unit wherein the detected degree of motion is compensated;
• a quantizing step for converting an estimation error, being the difference between the block unit of the said current frame and a motion compensated estimated unit, into a transform coefficient in the frequency domain, and for quantizing said transform coefficient in accordance with a predetermined quantization step size.
• a storing step for storing a motion vector varying in dependance upon the degree of motion detected in said local decoding step and the quantized transform coefficient from said quantizing step and for outputting a value indicative of buffer fullness;
• a first detecting step for detecting an image complexity variable with respect to a predetermined block unit of said current frame;
• a second detecting step for detecting a picture brightness variable with respect to a predetermined block unit of said current frame;
• and
• a fuzzy quantizing control step for fuzzifying input variables respectively representing said detected motion vector, image complexity, picture brightness and buffer fullness, and for determining a quantization step size for said quantizing step by performing a predetermined fuzzy reasoning operation on the fuzzified said input variables, in accordance with a predetermined fuzzy control regulation, and by subsequently performing a predetermined defuzzification operation on the reasoned result.

A fuzzy-controlled coder having a quantizer for controlling the quantization of an image signal according to a quantization step size determined by at least one among the input variables respectively representing image complexity, buffer fullness, picture brightness and motion vector, said coder comprising:

• regulation storage means for storing fuzzy control regulations for determining a quantization step size from said input variables;
• fuzzification means for storing linguistic truth values related to each of said input variables and a first membership function corresponding to each said linguistic truth values, and for generating a membership grade and a corresponding linguistic truth value with respect to at least one of said input variables with respect to a predetermined block of an image frame to be quantized;
• fuzzy reasoning means for reading the fuzzy control regulations determined by said membership grade and the corresponding linguistic truth value from said regulation storage means, and for generating a second membership function by performing a reasoning operation on said membership grade generated by said fuzzification means and on the corresponding linguistic truth value;
• and
• defuzzifier means for defuzzifying the second membership function generated by said fuzzy reasoning means according to a predetermined defuzzifying operation, and thereby generating a quantization step size.

A fuzzy-controlled coder for coding successive image frames each expressing at least one image, wherein a quantization step size is controlled in accordance with predetermined block units of said frame, said coder comprising:

• local decoding means for detecting a degree of motion between a predetermined block unit of a previous frame and a predetermined block unit of the current frame, and for extracting therefrom an estimation block wherein the detected degree of motion is compensated;
• quantizer means for converting an estimation error being a difference between a block unit of said current frame and the motion compensated estimation block data, into a transform coefficient in the frequency domain, and for quantizing said transform coefficient in accordance with a predetermined quantization step size;
• buffer means for storing a motion vector representing the degree of motion detected by said local decoding means, and for storing the quantized output from said quantizer means and for outputting a buffer fullness indication;
• a forward analyzer means for detecting image complexity with respect to said predetermined block unit of said current frame;
• a luminance analyzer means for detecting picture brightness with respect to said predetermined block unit of said current frame;
• and
• a fuzzy bit rate controller for controlling a bit rate of data, and for fuzzifying input variables respectively representing said detected motion vector, image complexity, picture brightness and buffer fullness indication, and for determining a quantization step size of said quantizer means by performing a predetermined fuzzy reasoning operation on said fuzzified input variables in accordance with a predetermined fuzzy control regulation, and by subsequently performing a predetermined defuzzification operation on the reasoned result, and for outputting the defuzzified result of said quantization step size.