Compression coding device and expansion decoding device for picture signal

A device for decoding a picture signal by expanding compression-coded digital picture data representative of a single picture by two-dimensional inverse orthogonal transform, comprising:

• decoding means for decoding the picture data, said decoding means decodes the picture data to produce a run-length of zeros and an amplitude of non-zeros;
• data selecting means for selecting at least one of the decoded data produced by said decoding means and the picture data, said data selecting means producing decoded data by using the amplitude of non-zeros decoded by said decoding means and the picture data;
• inverse normalizing means for inversely normalizing the data selected by said data selecting means;
• inverse orthogonal transforming means for applying two-dimensional inverse orthogonal transform to the inversely normalized data produced by said inverse normalizing means;
• and
• overflow detecting means for detecting, in response to the decoded data produced by said decoding means, that the picture data has an amplitude which exceeds a predetermined range;
• said data selecting means selecting, when said overflow detecting means detects that the amplitude of the picture data exceeds said predetermined range, the picture data in addition to the decoded data produced by said decoding means.

A device for decoding a picture signal by expanding compression-coded digital picture data representative of a single picture by two-dimensional inverse orthogonal transform, comprising:

• decoding means for decoding the picture data;
• data selecting means for selecting at least one of the decoded data produced by said decoding means and the picture data;
• inverse normalizing means for inversely normalizing the data selected by said data selecting means;
• inverse orthogonal transforming means for applying two-dimensional inverse orthogonal transform to the inversely normalized data produced by said inverse normalizing means;
• and
• overflow detecting means for detecting, in response to the decoded data produced by said decoding means, that the picture data has an amplitude which exceeds a predetermined range;
• said data selecting means selecting, when said overflow detecting means detects that the amplitude of the picture data exceeds said predetermined range, the picture data in addition to the decoded data produced by said decoding means;
• said inverse normalizing means uses an inverse normalizing coefficient and table data for normalizing the data by multiplying data produced from multiplying said inverse normalizing coefficient and said table data with the data selected by said data selecting means.

A device for decoding a picture signal by expanding compression-coded digital picture data representative of a single picture, comprising:

• Huffman decoding means for Huffman decoding the picture data;
• code detecting means, operatively communicative with said Huffman decoding means, for detecting a predetermined code when the picture data includes said predetermined code;
• code decoding means, operatively communicative with said code detecting means, for decoding the picture data which includes said predetermined code;
• said code detecting means causing said code decoding means to decode the picture data when said code detecting means detects said predetermined code in the picture data and causing said Huffman decoding means to decode the picture data when said code detecting means fails to detect said predetermined code in the picture data.

A method for coding a picture signal by dividing a single picture of digital picture data into a plurality of blocks and compressing said digital picture data block by block, comprising the steps of:

• (a) coding each of the plurality of blocks of the digital picture data;
• (b) detecting whether the individual blocks of the digital picture data lie in a predetermined range;
• (c) producing output data which includes the data coded at said step (a);
• (d) outputting data specifying the digital picture data in addition to the data coded at said step (a) depending on whether the digital picture data lies in said predetermined range;
• (e) applying two-dimensional orthogonal transform to the individual blocks of the digital picture data;
• (f) normalizing the data transformed at said step (e);
• (g) coding the data normalized at said step (f);
• (h) detecting whether an amplitude of the data normalized at said step (f) has exceeded said predetermined range;
• and
• (i) outputting the data specifying the data normalized at said step (f) in addition to the data coded at said step (g) when the amplitude of the normalized data exceeds said predetermined range.

A method for decoding a picture signal by expanding compression-coded digital picture data representative of a single picture inputted to a decoding device by two-dimensional inverse orthogonal transform, comprising the steps of:

• (a) decoding the compression-coded digital picture data into first and second data and a switch signal;
• (b) detecting whether the second data decoded at said step (a) has an amplitude exceeding a predetermined range and selecting decoded transform coefficients based on this detection;
• (c) selecting at least one of the first data decoded at said step (a) and the second data detected at said step (b) in response to said switch signal;
• (d) inversely normalizing the data selected at said step (c);
• and
• (e) applying two-dimensional inverse orthogonal transform to the data inversely normalized at said step (d).

A method for decoding a picture signal by expanding compression-coded digital picture data representative of a single picture inputted to a decoding device, comprising the steps of:

• (a) detecting whether the picture data includes a predetermined shift code;
• (b) decoding the picture data which includes said predetermined shift code when said step (a) detects the picture data to include said predetermined shift code;
• and
• (c) Huffman decoding the picture data when said predetermined shift code fails to be detected in the picture data at said step (a).