Image signal transforming and inverse-transforming method and computer program product with pre-encoding filtering features

Abstract

An aspect of an image signal transforming method is a method of generating one or more transformed samples from a plurality of input samples, which includes a first transformed sample generating step of performing a first filtering process by a filter, on at least one first input sample (an input sample from a terminal) out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process (subtraction by a subtractor) on another first input sample not used for the generation of the first filtered data (an input sample from another terminal), and the first filtered data generated, to generate the first transformed sample.

1 . An image signal transforming method of generating one or more transformed samples from a plurality of input samples, comprising:
 a first transformed sample generating step of performing a first filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and said first filtered data generated, to generate the first transformed sample.   
   
   
       2 . The image signal transforming method according to  claim 1 , further comprising a second transformed sample generating step of performing a second filtering process on the first transformed sample generated in the first transformed sample generating step, to generate second filtered data, and performing a second arithmetic process on at least one second input sample used for generation of a second transformed sample, and said second filtered data generated, to generate the second transformed sample. 
   
   
       3 . The image signal transforming method according to  claim 1 , further comprising a second transformed sample generating step of performing a second filtering process on at least one second input sample out of a plurality of second input samples used for generation of a second transformed sample, to generate second filtered data, and performing a second arithmetic process on another second input sample not used for the generation of the second filtered data, and said second filtered data generated, to generate the second transformed sample. 
   
   
       4 . An image encoding apparatus comprising:
 importing means for importing an input image as an object for coding;   region decomposing means for decomposing the input image imported by the importing means, into a plurality of coding regions;   predicting means for obtaining a differential signal by either intra-frame prediction or inter-frame prediction, for each of the coding regions resulting from the decomposition by the region decomposing means, and for generating the obtained differential signal as a transformation object signal;   transforming means for generating a transformed sample, using the transformation object signal generated by the predicting means, as an input sample, based on an image signal transforming method of generating one or more transformed samples from a plurality of input samples, which comprises a first transformed sample generating step of performing a filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and the first filtered data generated, to generate the first transformed sample, and for defining the generated transformed sample as a transformation coefficient, thereby transforming the transformation object signal into the transformation coefficient; and   encoding means for encoding the transformation coefficient obtained by the transforming means.   
   
   
       5 . The image encoding apparatus according to  claim 4 , wherein the transforming means selects and uses a filter to maximize a correlation of the transformation object signal, out of plural types of filters in the filtering process, and further encodes identification information for identification of the selected filter. 
   
   
       6 . An image decoding apparatus comprising:
 importing means for importing compressed data generated by performing either intra-frame prediction or inter-frame prediction, for an image decomposed into a plurality of regions, and performing transformation and coding;   decoding means for restoring transformation coefficients corresponding to said respective regions from the compressed data imported by the importing means, and for generating the resultant transformation coefficients as restored transformation coefficients; and   inversely transforming means for generating a transformed sample, using the restored transformation coefficients generated by the decoding means, as input samples, based on an image signal transforming method of generating one or more transformed samples from a plurality of input samples, which comprises a first transformed sample generating step of performing a filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and the first filtered data generated, to generate the first transformed sample, and for defining the generated transformed sample as inversely transformed data, thereby transforming the restored transformation coefficients into the inversely transformed data.   
   
   
       7 . The image decoding apparatus according to  claim 6 , wherein the compressed data contains filter identification information for identification of a filter used in the filtering process, and
 wherein the decoding means decodes the filter identification information and performs the filtering process using the filter corresponding to the decoded filter identification information.   
   
   
       8 . An image encoding method comprising:
 an importing step of importing an input image as an object for coding;   a region decomposing step of decomposing the input image imported in the importing step, into a plurality of coding regions;   a predicting step of obtaining a differential signal by either intra-frame prediction or inter-frame prediction, for each of the coding regions resulting from the decomposition in the region decomposing step, and generating the obtained differential signal as a transformation object signal;   a transforming step of generating a transformed sample, using the transformation object signal generated in the predicting step, as an input sample, based on an image signal transforming method of generating one or more transformed samples from a plurality of input samples, which comprises a first transformed sample generating step of performing a filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and the first filtered data generated, to generate the first transformed sample, and defining the generated transformed sample as a transformation coefficient, thereby transforming the transformation object signal into the transformation coefficient; and   an encoding step of encoding the transformation coefficient obtained in the transforming step.   
   
   
       9 . An image decoding method comprising:
 an importing step of importing compressed data generated by performing either intra-frame prediction or inter-frame prediction, for an image decomposed into a plurality of regions, and performing transformation and coding;   a decoding step of restoring transformation coefficients corresponding to said respective regions from the compressed data imported in the importing step, and generating the resultant transformation coefficients as restored transformation coefficients; and   an inversely transforming step of generating a transformed sample, using the restored transformation coefficients generated in the decoding step, as input samples, based on an image signal transforming method of generating one or more transformed samples from a plurality of input samples, which comprises a first transformed sample generating step of performing a filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and the first filtered data generated, to generate the first transformed sample, and defining the generated transformed sample as inversely transformed data, thereby transforming the restored transformation coefficients into the inversely transformed data.   
   
   
       10 . An image encoding program for letting a computer execute the following steps:
 an importing step of importing an input image as an object for coding;   a region decomposing step of decomposing the input image imported in the importing step, into a plurality of coding regions;   a predicting step of obtaining a differential signal by either intra-frame prediction or inter-frame prediction, for each of the coding regions resulting from the decomposition in the region decomposing step, and generating the obtained differential signal as a transformation object signal;   a transforming step of generating a transformed sample, using the transformation object signal generated in the predicting step, as an input sample, based on an image signal transforming method of generating one or more transformed samples from a plurality of input samples, which comprises a first transformed sample generating step of performing a filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and the first filtered data generated, to generate the first transformed sample, and defining the generated transformed sample as a transformation coefficient, thereby transforming the transformation object signal into the transformation coefficient; and   an encoding step of encoding the transformation coefficient obtained in the transforming step.   
   
   
       11 . An image decoding program for letting a computer execute the following steps:
 an importing step of importing compressed data generated by performing either intra-frame prediction or inter-frame prediction, for an image decomposed into a plurality of regions, and performing transformation and coding;   a decoding step of restoring transformation coefficients corresponding to said respective regions from the compressed data imported in the importing step, and generating the resultant transformation coefficients as restored transformation coefficients; and   an inversely transforming step of generating a transformed sample, using the restored transformation coefficients generated in the decoding step, as input samples, based on an image signal transforming method of generating one or more transformed samples from a plurality of input samples, which comprises a first transformed sample generating step of performing a filtering process on at least one first input sample out of a plurality of first input samples used for generation of a first transformed sample, to generate first filtered data, and performing a first arithmetic process on another first input sample not used for the generation of the first filtered data, and the first filtered data generated, to generate the first transformed sample, and defining the generated transformed sample as inversely transformed data, thereby transforming the restored transformation coefficients into the inversely transformed data.   
   
   
       12 . An image signal transforming method of generating 2 N  transformed samples from 2 N  (N is a natural number) input samples in accordance with a predetermined transformation rule, comprising:
 an intermediate value generating step of weighting one input sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of input samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and   a transformation coefficient generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of transformed samples.   
   
   
       13 . An image signal inversely-transforming method of generating 2 N  output samples from 2 N  (N is a natural number) transformed samples in accordance with a predetermined transformation rule, comprising:
 an intermediate value generating step of weighting one transformed sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of transformed samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and   an output value generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of output samples.   
   
   
       14 . An image encoding apparatus comprising:
 importing means for importing an input image as an object for coding;   region decomposing means for decomposing the input image imported by the importing means, into a plurality of coding regions;   predicting means for obtaining a differential signal by either intra-frame prediction or inter-frame prediction, for each of the coding regions resulting from the decomposition by the region decomposing means, and for generating the differential signal as a transformation object signal;   transforming means for generating a transformed sample, using the transformation object signal generated by the predicting means, as an input sample, based on an image signal transforming method of generating 2 N  transformed samples from 2 N  (N is a natural number) input samples in accordance with a predetermined transformation rule, which comprises: an intermediate value generating step of weighting one input sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of input samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and a transformation coefficient generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of transformed samples, and for defining the generated transformed sample as a transformation coefficient, thereby transforming the transformation object signal into the transformation coefficient; and   encoding means for encoding the transformation coefficient obtained by the transforming means.   
   
   
       15 . The image encoding apparatus according to  claim 14 , wherein the transforming means selects a weighting factor to maximize a degree of energy concentration of the transformation object signal, out of a plurality of weighting factors in the intermediate value generating step and in the transformation coefficient generating step, and wherein identification information of the weighting factor is further encoded. 
   
   
       16 . An image decoding apparatus comprising:
 importing means for importing compressed data generated by performing either intra-frame prediction or inter-frame prediction, for an image decomposed into a plurality of regions, and for performing transformation and coding;   decoding means for restoring transformation coefficients corresponding to the respective regions from the compressed data imported by the importing means, and for generating the resultant transformation coefficients as restored transformation coefficients; and   inversely transforming means for generating an output sample, using the restored transformation coefficients generated by the decoding means, as transformed samples, based on an image signal inversely-transforming method of generating 2 N  output samples from 2 N  (N is a natural number) transformed samples in accordance with a predetermined transformation rule, which comprises: an intermediate value generating step of weighting one transformed sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of transformed samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and an output value generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of output samples, and for defining the output sample as inversely transformed data, thereby transforming the restored transformation coefficients into the inversely transformed data.   
   
   
       17 . The image decoding apparatus according to  claim 16 , wherein the compressed data contains identification information of the weighting factor used in the intermediate value generating step or in the output value generating step, and
 wherein the decoding means decodes the identification information and performs the process of the intermediate value generating step or the output value generating step, using the weighting factor corresponding to the identification information.   
   
   
       18 . An image encoding method comprising:
 an importing step of importing an input image as an object for coding;   a region decomposing step of decomposing the input image imported in the importing step, into a plurality of coding regions;   a predicting step of obtaining a differential signal by either intra-frame prediction or inter-frame prediction, for each of the coding regions resulting from the decomposition in the region decomposing step, and generating the differential signal as a transformation object signal;   a transforming step of generating a transformed sample, using the transformation object signal generated in the predicting step, as an input sample, based on an image signal transforming method of generating 2 N  transformed samples from 2 N  (N is a natural number) input samples in accordance with a predetermined transformation rule, which comprises: an intermediate value generating step of weighting one input sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of input samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and a transformation coefficient generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of transformed samples, and defining the generated transformed sample as a transformation coefficient, thereby transforming the transformation object signal into the transformation coefficient; and   an encoding step of encoding the transformation coefficient obtained in the transforming step.   
   
   
       19 . An image decoding method comprising:
 an importing step of importing compressed data generated by performing either intra-frame prediction or inter-frame prediction, for an image decomposed into a plurality of regions, and performing transformation and coding;   a decoding step of restoring transformation coefficients corresponding to the respective regions from the compressed data imported in the importing step, and generating the resultant transformation coefficients as restored transformation coefficients; and   an inversely transforming step of generating an output sample, using the restored transformation coefficients generated in the decoding step, as transformed samples, based on an image signal inversely-transforming method of generating 2 N  output samples from 2 N  (N is a natural number) transformed samples in accordance with a predetermined transformation rule, which comprises: an intermediate value generating step of weighting one transformed sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of transformed samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and an output value generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of output samples, and defining the output sample as inversely transformed data, thereby transforming the restored transformation coefficients into the inversely transformed data.   
   
   
       20 . An image encoding program for letting a computer execute the following processes:
 a process of importing an input image as an object for coding;   a process of decomposing the input image imported, into a plurality of coding regions;   a process of obtaining a differential signal by either intra-frame prediction or inter-frame prediction, for each of the coding regions resulting from the decomposition, and generating the differential signal as a transformation object signal;   a process of generating a transformed sample, using the generated transformation object signal as an input sample, based on an image signal transforming method of generating 2 N  transformed samples from 2 N  (N is a natural number) input samples in accordance with a predetermined transformation rule, which comprises: an intermediate value generating step of weighting one input sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of input samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and a transformation coefficient generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of transformed samples, and defining the generated transformed sample as a transformation coefficient, thereby transforming the transformation object signal into the transformation coefficient; and   a process of encoding the transformation coefficient obtained.   
   
   
       21 . An image decoding program for letting a computer execute the following processes:
 a process of importing compressed data generated by performing either intra-frame prediction or inter-frame prediction, for an image decomposed into a plurality of regions, and performing transformation and coding;   a process of restoring transformation coefficients corresponding to the respective regions from the compressed data imported, and generating the resultant transformation coefficients as restored transformation coefficients; and   a process of generating an output sample, using the restored transformation coefficients as transformed samples, based on an image signal inversely-transforming method of generating 2 N  output samples from 2 N  (N is a natural number) transformed samples in accordance with a predetermined transformation rule, which comprises: an intermediate value generating step of weighting one transformed sample out of an n-th pair (1≦n≦2 N−1 , n is a natural number) of transformed samples determined in accordance with the transformation rule, by an n-th weighting factor, and performing a first transformation arithmetic to generate an n-th pair of intermediate values; and an output value generating step of importing 2 N  intermediate values generated in the intermediate value generating step, weighting one intermediate value out of an m-th pair (1≦m≦2 N−1 , m is a natural number) of intermediate values determined in accordance with the transformation rule, by an m-th weighting factor, and performing a second transformation arithmetic to generate an m-th pair of output samples, and defining the output sample as inversely transformed data, thereby transforming the restored transformation coefficients into the inversely transformed data.