2-Dimensional signal encoding/decoding method and device

An encoding device characterized by comprising:

• element extracting means for sequentially extracting 2m×2 (m is an integer:
• m≧1) spatially adjacent elements from a two-dimensional signal;
• wavelet transforming means for dividing the 2m×2 elements into a plurality of subband coefficient sets;
• coefficient encoding means for encoding the coefficient sets;
• and
• code output means for rearranging the encoded coefficient sets in order from a low-resolution subband, and outputting the rearranged coefficient sets.

A decoding device characterized by comprising:

• initial coefficient decoding means for receiving a code sequence formed by encoding coefficients of a plurality of subbands obtained by wavelet transform, and decoding a coefficient of a lowest-frequency subband from a code sequence corresponding to the lowest-frequency subband;
• coefficient decoding means for decoding sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position in a plurality of subbands which belong to a wavelet transform level of the same hierarchy from a code sequence following the lowest-frequency subband code sequence;
• and
• inverse wavelet transforming means for performing inverse wavelet transform whenever the coefficient set is decoded, thereby generating the original two-dimensional signal.

An encoding method characterized by comprising the steps of:

• dividing a two-dimensional signal into subbands as a plurality of frequency regions by wavelet transform;
• extracting sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position from a plurality of subbands which belong to a wavelet decomposition level of the same hierarchy;
• and
• encoding the extracted coefficient sets.

An encoding method characterized by comprising the steps of:

• sequentially extracting 2m×2 (m is an integer:
• m≧1) spatially adjacent elements from a two-dimensional signal;
• dividing the 2m×2 elements into a plurality of subband coefficient sets by wavelet transform;
• encoding the coefficient sets;
• and
• rearranging the encoded coefficient sets in order from a low-resolution subband, and outputting the rearranged coefficient sets.

A decoding method characterized by comprising the steps of:

• receiving a code sequence formed by encoding coefficients of a plurality of subbands obtained by wavelet transform;
• decoding a coefficient of a lowest-frequency subband from a code sequence corresponding to the lowest-frequency subband;
• decoding sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position in a plurality of subbands which belong to a wavelet transform level of the same hierarchy from a code sequence following the lowest-frequency subband code sequence;
• and
• performing inverse wavelet transform whenever the coefficient set is decoded, thereby generating the original two-dimensional signal.

An encoding program characterized by causing a computer to execute the steps of:

• dividing a two-dimensional signal into subbands as a plurality of frequency regions by wavelet transform;
• extracting sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position from a plurality of subbands which belong to a wavelet decomposition level of the same hierarchy;
• and
• encoding the extracted coefficient sets.

An encoding program characterized by causing a computer to execute the steps of:

• sequentially extracting 2m×2 (m is an integer:
• m≧1) spatially adjacent elements from a two-dimensional signal;
• dividing the 2m×2 elements into a plurality of subband coefficient sets by wavelet transform;
• encoding the coefficient sets;
• and
• rearranging the encoded coefficient sets in order from a low-resolution subband, and outputting the rearranged coefficient sets.

A decoding program characterized by causing a computer to execute the steps of:

• receiving a code sequence formed by encoding coefficients of a plurality of subbands obtained by wavelet transform;
• decoding a coefficient of a lowest-frequency subband from a code sequence corresponding to the lowest-frequency subband;
• decoding sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position in a plurality of subbands which belong to a wavelet transform level of the same hierarchy from a code sequence following the lowest-frequency subband code sequence;
• and
• performing inverse wavelet transform whenever the coefficient set is decoded, thereby generating the original two-dimensional signal.

A communication terminal characterized by comprising:

• image input means;
• communicating means for transmitting and receiving an encoded image signal;
• wavelet transforming means for dividing an image signal to be transmitted, which is input by said image input means, into subbands as a plurality of frequency regions;
• coefficient extracting means for extracting sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position from a plurality of subbands which belong to a wavelet decomposition level of the same hierarchy;
• coefficient encoding means for encoding the extracted coefficient sets, and outputting the encoded coefficient sets to said communicating means;
• initial coefficient decoding means for decoding a coefficient of a lowest-frequency subband of a received image signal from a code sequence corresponding to the lowest-frequency subband;
• coefficient decoding means for decoding sets of coefficients for every predetermined number of sets of coefficients which belong to the same spatial position in a plurality of subbands which belong to a wavelet transform level of the same hierarchy from a code sequence following the lowest-frequency subband code sequence;
• inverse wavelet transforming means for performing inverse wavelet transform whenever the coefficient set is decoded, thereby generating the received image signal;
• and
• image display means for displaying a received image on the basis of the received image signal.