Image processing device and method with a scalable quantization matrix

1. An image processing device comprising:

circuitry configured to:

decode encoded data including an initial difference coefficient that is a difference between a replacement coefficient and a predetermined initial value, a replacement difference coefficient that is a difference between the replacement coefficient and a (0, 0) coefficient of a first quantization matrix, and element difference coefficients each being a difference between two adjacent coefficients in a sequence of coefficients of the first quantization matrix arranged in a scan order, a size of the first quantization matrix being no greater than a maximum size for transmission;

set the replacement coefficient by adding the initial value to the initial difference coefficient;

set the (0, 0) coefficient of the first quantization matrix by adding the replacement coefficient to the replacement difference coefficient;

set remaining coefficients of the first quantization matrix by stepwise adding the element difference coefficients to the (0, 0) coefficient of the first quantization matrix, wherein a remaining coefficient at a particular position in the scan order is the sum of the (0, 0) coefficient of the first quantization matrix and one or more difference coefficients up to the particular position;

up-convert the first quantization matrix into a second quantization matrix by performing a nearest neighbor interpolation process on matrix elements of the first quantization matrix;

replace a (0, 0) coefficient of the second quantization matrix set by up-conversion with the replacement coefficient; and

dequantize quantized data obtained by decoding encoded data for generating a decoded image for output, using the second quantization matrix in which the (0, 0) coefficient of the second quantization matrix has been replaced with the replacement coefficient by the circuitry.

2. The image processing device according to claim 1 , wherein

the initial difference coefficient, the replacement difference coefficient, and the element difference coefficients have been encoded, and

the circuitry is configured to decode the encoded initial difference coefficient, the encoded replacement difference coefficient, and the encoded element difference coefficients.

3. The image processing device according to claim 1 , wherein

the first quantization matrix is an 8×8 quantization matrix, and

the second quantization matrix is a 16×16 quantization matrix.

4. The image processing device according to claim 1 , wherein

the first quantization matrix is an 8×8 quantization matrix, and

the second quantization matrix is a 32×32 quantization matrix.

5. An image processing method, comprising:

decoding encoded data including an initial difference coefficient that is a difference between a replacement coefficient and a predetermined initial value, a replacement difference coefficient that is a difference between the replacement coefficient and a (0, 0) coefficient of a first quantization matrix, and element difference coefficients each being a difference between two adjacent coefficients in a sequence of coefficients of the first quantization matrix arranged in a scan order, a size of the first quantization matrix being no greater than a maximum size for transmission;

setting, by circuitry of a device, the replacement coefficient by adding the initial value to the initial difference coefficient;

setting, by the circuitry of the device, the (0, 0) coefficient of the first quantization matrix by adding the replacement coefficient to the replacement difference coefficient;

setting, by the circuitry of the device, remaining coefficients of the first quantization matrix by stepwise adding the element difference coefficients to the (0, 0) coefficient of the first quantization matrix, wherein a remaining coefficient at a particular position in the scan order is the sum of the (0, 0) coefficient of the first quantization matrix and one or more difference coefficients up to the particular position;

up-converting the first quantization matrix into a second quantization matrix by performing a nearest neighbor interpolation process on matrix elements of the first quantization matrix;

replacing a (0, 0) coefficient of the second quantization matrix set by up-conversion with the replacement coefficient; and

dequantizing quantized data obtained by decoding encoded data for generating a decoded image for output, using the second quantization matrix in which the (0, 0) coefficient of the second quantization matrix has been replaced with the replacement coefficient by the circuitry.

6. The image processing method according to claim 5 , wherein

the initial difference coefficient, the replacement difference coefficient, and the element difference coefficients have been encoded, and

the method further comprises decoding the encoded initial difference coefficient, the encoded replacement difference coefficient, and the encoded element difference coefficients.

7. The image processing method according to claim 5 , wherein

the first quantization matrix is an 8×8 quantization matrix, and

the second quantization matrix is a 16×16 quantization matrix.

8. The image processing method according to claim 5 , wherein

the first quantization matrix is an 8×8 quantization matrix, and

the second quantization matrix is a 32×32 quantization matrix.