Apparatus and method for image encoding, apparatus and method for image decoding, and image transmission system

An image decoding apparatus comprising:

• a processor configured to perform a procedure including:
• extracting, from encoded video data input thereto, a first code and a second code corresponding to a first operating mode and a second operating mode, respectively, of an adaptive filter,
• identifying the first operating mode based on the first code,
• identifying the second operating mode as an operating mode having higher similarities to the identified first operating mode when a bit number of the second code is lower,
• performing a process using the adaptive filter on a first signal of a block in a decoded image reconstructed from the encoded video data according to the identified first operating mode, and
• performing the process using the adaptive filter on a second signal of the block according to the identified second operating mode.

An image decoding method comprising:

• extracting, by a computer, from encoded video data input thereto, a first code and a second code corresponding to a first operating mode and a second operating mode, respectively, of an adaptive filter;
• identifying, by the computer, the first operating mode based on the first code;
• identifying, by the computer, the second operating mode as an operating mode having higher similarities to the identified first operating mode when a bit number of the second code is lower;
• performing, by the computer, a process using the adaptive filter on a first signal of a block in a decoded image reconstructed from the encoded video data according to the identified first operating mode;
• and
• performing, by the computer, the process using the adaptive filter on a second signal of the block according to the identified second operating mode.

A non-transitory computer-readable storage medium storing an image decoding program that causes a computer to perform a procedure comprising:

• extracting, from encoded video data input thereto, a first code and a second code corresponding to a first operating mode and a second operating mode, respectively, of an adaptive filter;
• identifying the first operating mode based on the first code;
• identifying the second operating mode as an operating mode having higher similarities to the identified first operating mode when a bit number of the second code is lower;
• performing a process using the adaptive filter on a first signal of a block in a decoded image reconstructed from the encoded video data according to the identified first operating mode;
• and
• performing the process using the adaptive filter on a second signal of the block according to the identified second operating mode.

An image transmission system comprising:

• an image encoding apparatus configured to generate encoded video data;
• and
• an image decoding apparatus configured to decode the encoded video data,
• wherein the image encoding apparatus includes a first processor configured to perform a procedure including:
• determining a first operating mode and a second operating mode of an adaptive filter that is applied to a block in an input image in decoding, the determining including determining the first operating mode based on a first signal of the input image and determining the second operating mode based on a second signal of the input image, and
• encoding the second operating mode by assigning a code with a lower bit number to the second operating mode when the second operating mode has higher similarities to the first operating mode, and
• the image decoding apparatus includes a second processor configured to perform a procedure including:
• extracting the first code and the second code from the encoded video data,
• identifying the first operating mode based on the first code,
• identifying the second operating mode as an operating mode having higher similarities to the identified first operating mode when a bit number of the second code is lower,
• performing a process using the adaptive filter on a first signal of the block decoded from the encoded video data according to the identified first operating mode, and
• performing the process using the adaptive filter on a second signal of the block according to the identified second operating mode.