Image coding apparatus, image coding method, and program, and image decoding apparatus, image decoding method and program

An image decoding apparatus decoding a bit stream generated by encoding an image, the apparatus comprising:

• a first decoding unit configured to decode a block to be processed using a first decoding process including transformation process;
• and
• a second decoding unit configured to decode a block to be processed using a second decoding process not including the transformation process,
• wherein the second decoding unit is capable of applying at least either the second decoding process using an intra prediction mode in which a pixel not included in the block to be processed is used or the second decoding process using a DPCM process on a basis of a pixel included in the block to be processed,
• wherein a first flag independent from prediction mode information about the intra prediction mode is decoded, the first flag being used to determine whether the second decoding process using the DPCM process is applied or not for the block to be processed,
• wherein it is determined, in a unit of a block included in the image, whether the second decoding process using the DPCM process is applied or not, in accordance with the first flag,
• wherein the second decoding process using the DPCM process is applied for the block to be processed, in a case where it is determined based on the first flag that the second decoding process using the DPCM process is applied for the block to be processed.

An image encoding method for encoding an image, the method comprising:

• encoding a block to be processed using first encoding process including a transformation process;
• and
• encoding a block to be processed using a second encoding process not including the transformation process;
• wherein the encoding the block to be processed using the second encoding process is capable of applying at least either one of the second encoding process using an intra prediction mode in which a pixel not including in the block to be processed is used or the second encoding process using a DPCM process on a basis of a pixel included in the block to be processed, wherein if the second encoding process is used, a first flag independent from prediction mode information about the intra prediction mode is coded in a unit of a block included in the image, the first flag being used to determine whether a decoding process corresponding to the second encoding process using the DPCM process is applied or not for a block to be processed.

An image decoding method for decoding a bit stream including coded data generated by encoding an image, the method comprising:

• decoding a block to be processed using a first decoding process including a transformation process;
• and
• decoding a block to be processed using a second decoding process not including the transformation process,
• wherein the decoding the block to be processed using the second decoding process is capable of applying at least either the second decoding process using an intra prediction mode in which a pixel not included in the block to be processed is used or the second decoding process using a DPCM process on a basis of a pixel included in the block to be processed,
• wherein a first flag independent from prediction mode information about the intra prediction mode is decoded, the first flag being used to determine whether the second decoding process using the DPCM process is applied or not for the block to be processed,
• wherein it is determined, in a unit of a block included in the image, whether the second decoding process using the DPCM process is applied or not, in accordance with the first flag, and
• wherein the second decoding process using the DPCM process is applied for the block to be processed, in a case where it is determined based on the first flag that the second decoding process using the DPCM process is applied for the block to be processed.

A non-transitory computer-readable storage medium storing a program for causing a computer to execute encoding of an image, the program comprising:

• computer-executable instructions for encoding a block to be processed using first encoding process a transformation process;
• and
• computer-executable instructions for encoding a block to be processed using a second encoding process not including the transformation process,
• wherein the encoding the block to be processed using the second encoding process is capable of applying at least either one of the second encoding process using an intra prediction mode in which a pixel not included in the block to be processed is used or the second encoding process using a DPCM process on a basis of a pixel included in the block to be processed,
• wherein if the second encoding process is used, a first flag independent from prediction mode information about the intra prediction mode is coded in a unit of a block included in the image, the first flag being used to determine whether a decoding process corresponding to the second encoding process using the DPCM process is applied or not for a block to be processed.

A non-transitory computer-readable storage medium storing a program for causing a computer to execute decoding of a bit stream including coded data generated by encoding an image, the program comprising:

• computer-executable instructions for decoding a block to be processed using a first decoding process including a transformation process;
• computer-executable instructions for decoding a block to be processed using a second decoding process not including the transformation process,
• wherein the decoding the block to be processed using the second decoding process is capable of applying at least either the second decoding process using an intra prediction mode in which a pixel not included in the block to be processed is used or the second decoding process using a DPCM process on a basis of a pixel included in the block to be processed,
• wherein a first flag independent from prediction mode information about the intra prediction mode is decoded, the first flag being used to determine whether the second decoding process using the DPCM process is applied or not for the block to be processed,
• wherein it is determined, in a unit of a block included in the image, whether the second decoding process using the DPCM process is applied or not, in accordance with the first flag, and
• wherein the second decoding process using the DPCM process is applied for the block to be processed, in a case where it is determined based on the first flag that the second decoding process using the DPCM process is applied for the block to be processed.