Image coding system which limits number of variable length code words

An image encoding control system for encoding an input image signal representing an image defined by a plurality of pixels, said image encoding control system comprising:

• orthogonal transform encoding means for dividing said input image signal into a plurality of blocks and for performing orthogonal transform encoding of each block and thereby producing, as outputs, transform coefficients for each block related to the plurality of pixels;
• code control means for receiving said transform coefficients for each block, as output by said orthogonal transform encoding means, identifying a limited number of said transform coefficients which are indicative of a number of variable-length code words for each block not larger than a predetermined number and outputting said limited number of said transform coefficients;
• variable-length encoding means for receiving said limited number of said transform coefficients, as output by said code control means, converting said limited number of said transform coefficients for each block into said variable-length code words, and outputting the number of said variable length code words not larger than said predetermined number;
• and
• buffer memory means for temporarily storing said variable-length code words output by said variable-length encoding means for each block, wherein:
• each of said variable-length code words is a run-length code;
• and
• said code control means comprises:
• first count means for identifying effective coefficients of said transform coefficients and strings of consecutive zero transform coefficients, each effective coefficient being a non-zero transform coefficient, and for counting, for each block, a number of said effective coefficients and strings of consecutive zero transform coefficients;
• comparing means for comparing the number counted by said first count means with a predetermined threshold value;
• and
• select means, provided between said orthogonal transform encoding means and said variable-length encoding means, for enabling transmission of said transform coefficients output by said orthogonal transform encoding means when the number counted by said first count means is not larger than said predetermined threshold value based upon the comparison by said comparing means and not enabling transmission of said transform coefficients when the number of said effective coefficients exceeds said predetermined threshold value based upon the comparison by said comparing means.

An image encoding control system for encoding an input image signal representing a picture, said image encoding control system comprising:

• orthogonal transform encoding means for dividing the picture formed by the input image signal into a plurality of blocks each having a plurality of pixels, and for carrying out an orthogonal transform encoding for each block, to produce for each block transform coefficients related to the plurality of pixels;
• code control means for processing said transform coefficients of each block which have been scanned from low frequency to high frequency, identifying ones of said transform coefficients which are not zero as effective coefficients, and transmitting, for subsequent variable-length encoding, said transform coefficients in the scanned order until a predetermined number of the effective coefficients has been transmitted;
• variable-length encoding means for converting said transform coefficients obtained for each block and transmitted by said code control means into variable-length code words;
• and
• buffer means for temporarily storing said predetermined number of variable-length code words output by said variable-length encoding means for each block.

An image encoding control system for encoding an input image signal representing a picture, said image encoding control system comprising:

• orthogonal transform encoding means for dividing the picture formed by the input image signal into a plurality of blocks each having a plurality of pixels, and for carrying out an orthogonal transform encoding for each block, to produce for each block transform coefficients related to the plurality of pixels;
• code control means for processing said transform coefficients of each block which have been scanned from low frequency to high frequency, identifying only ones of said transform coefficients which are not zero as effective coefficients, and transmitting, for subsequent variable-length encoding, said transform coefficients in the scanned order until a predetermined number of the effective coefficients has been transmitted;
• variable-length encoding means for converting said transform coefficients obtained for each block and transmitted by said code control means into variable-length code words;
• and
• buffer means for temporarily storing said predetermined number of variable-length code words output by said variable-length encoding means for each block.