Image signal processing apparatus, image signal processing method, prediction coefficient generating apparatus, prediction coefficient generating method, and programs for causing computer to execute the methods

An image signal processing method comprising the steps of:

• dividing an image signal into first blocks and then encoding the image signal using orthogonal transformation;
• dividing the encoded image signal into second blocks different from the first blocks;
• calculating an activity of each of the divided second blocks;
• re-encoding the second blocks using the orthogonal transformation;
• calculating difference values between the re-encoded second blocks and the first blocks encoded using the orthogonal transformation;
• determining a class of each of the second blocks on the basis of a distribution of the calculated difference value and the activity;
• generating a prediction coefficient corresponding to the determined class;
• constructing a prediction tap for calculating a target pixel in each of the second blocks;
• and
• operating the constructed prediction tap and the prediction coefficient to calculate a pixel value of the target pixel.

A program for causing a computer to execute an image signal processing method comprising the steps of:

• dividing an image signal into first blocks and then encoding the image signal using orthogonal transformation;
• dividing the encoded image signal into second blocks different from the first blocks;
• calculating an activity of each of the divided second blocks;
• re-encoding the second blocks using the orthogonal transformation;
• calculating difference values between the re-encoded second blocks and the first blocks encoded using the orthogonal transformation;
• determining a class of each of the second blocks on the basis of a distribution of the calculated difference value and the activity;
• generating a prediction coefficient corresponding to the determined class;
• constructing a prediction tap for calculating a target pixel in each of the second blocks;
• and
• operating the constructed prediction tap and the prediction coefficient to calculate a pixel value of the target pixel.

A prediction coefficient generating apparatus comprising:

• an encoding unit that encodes an image signal divided into first blocks using orthogonal transformation;
• a decoding unit that decodes the image signal encoded by the encoding unit;
• a block division unit that inputs the image signal decoded using the orthogonal transformation and that divides the encoded image signal into second blocks different from the first blocks encoded using the orthogonal transformation;
• an activity calculation unit that calculates an activity of each of the second blocks divided by the block division unit;
• a re-encoding unit that encodes the second blocks divided by the block division unit using the orthogonal transformation;
• a re-encoded difference calculation unit that calculates difference values between the second blocks re-encoded by the re-encoding unit and the first blocks encoded using the orthogonal transformation;
• a class determination unit that determines a class of each of the second blocks on the basis of a distribution of the difference value calculated by the re-encoded difference calculation unit and the activity calculated by the activity calculation unit;
• a prediction tap construction unit that constructs a prediction tap for calculating a target pixel in each of the second blocks;
• and
• a prediction coefficient operation unit that, for each position of a target pixel of each second block in the class, calculates a prediction coefficient that minimizes a difference between a pixel value of the target pixel and a pixel value of the corresponding first block on the basis of the class determined by the class determination unit, the prediction tap constructed by the prediction tap construction unit and pixels of the image signal divided into that first block.

A prediction coefficient generating method comprising the steps of:

• dividing an image signal into first blocks and then encoding the image signal using orthogonal transformation;
• decoding the encoded image signal;
• inputting the image signal encoded using the orthogonal transformation and dividing the encoded image signal into second blocks different from the first blocks;
• calculating an activity of each of the divided second blocks;
• re-encoding the second blocks using the orthogonal transformation;
• calculating difference values between the re-encoded second blocks and the first blocks encoded using the orthogonal transformation;
• determining a class of each of the second blocks on the basis of a distribution of the calculated difference value and the activity;
• constructing a prediction tap for calculating a target pixel in each of the second blocks;
• for each position of the target pixel of each second block in the class, calculating a prediction coefficient that minimizes a difference between a pixel value of the target pixel and a pixel value of the corresponding first block on the basis of the class, the prediction tap and pixels of the image signal divided into that first block.

A program for causing a computer to execute a prediction coefficient generating method comprising the steps of:

• dividing an image signal into first blocks and then encoding the image signal using orthogonal transformation;
• decoding the encoded image signal;
• inputting the image signal encoded using the orthogonal transformation and dividing the encoded image signal into second blocks different from the first blocks;
• calculating an activity of each of the divided second blocks;
• re-encoding the second blocks using the orthogonal transformation;
• calculating difference values between the re-encoded second blocks and the first blocks encoded using the orthogonal transformation;
• determining a class of each of the second blocks on the basis of a distribution of the calculated difference value and the activity;
• constructing a prediction tap for calculating a target pixel in each of the second blocks;
• for each position of the target pixel of each second block in the class, calculating a prediction coefficient that minimizes a difference between a pixel value of the target pixel and a pixel value of the corresponding first block on the basis of the class, the prediction tap and pixels of the image signal divided into that first block.