Image processing apparatus and method
There is provided an image processing apparatus and method that make it possible to suppress degradation of the encoding efficiency. In the case where primary transform that is a transform process for a prediction residual that is a difference between an image and a prediction image of the image is to be skipped, also secondary transform, which is a transform process for a primary transform coefficient obtained by the primary transform of the prediction residual, is skipped. The present disclosure can be applied, for example, to an image processing apparatus, an image encoding apparatus, an image decoding apparatus and so forth.
1 . An image processing apparatus, comprising:
circuitry configured to skip, where a primary transform that is a transform process for a prediction residual that is a difference between an image and a prediction image of the image, a secondary transform that is a transform process for a primary transform coefficient obtained by the primary transform of the prediction residual, and quantization for a secondary transform coefficient obtained by the secondary transform of the primary transform coefficient are to be skipped, encoding of first information indicative of a substance of the primary transform.
2 . The image processing apparatus according to claim 1 ,
wherein the first information comprises a primary transform identifier.
3 . The image processing apparatus according to claim 2 ,
wherein the primary transform identifier designates, for each transform block, which primary transform is to be applied in a horizontal direction and which primary transform is to be applied in a vertical direction.
4 . The image processing apparatus according to claim 3 ,
wherein the primary transform identifier indicates a first flag designating one of a plurality of transforms to be applied as the primary transform in the horizontal direction and indicating a second flag designating one of a plurality of transforms to be applied as the primary transform in the vertical direction.
5 . The image processing apparatus according to claim 4 ,
wherein encoding of the primary transform identifier comprises binarizing the primary transform identifier into a fixed length code.
6 . The image processing apparatus according to claim 5 ,
wherein binarizing the primary transform identifier comprises truncated unary binarization as a binarization method.
7 . An image processing apparatus, comprising:
circuitry configured to skip, where dequantization for a quantization transform coefficient level obtained by decoding encoded data, an inverse secondary transform for transforming a secondary transform coefficient obtained by the dequantization of the quantization transform coefficient level into a primary transform coefficient, and an inverse primary transform for transforming the primary transform coefficient into a prediction residual that is a difference between an image and a prediction image of the image are to be skipped, decoding of encoded data of first information relating to a substance of the inverse primary transform.
8 . The image processing apparatus according to claim 7 ,
wherein the first information comprises a primary transform identifier.
9 . The image processing apparatus according to claim 8 ,
wherein the primary transform identifier designates, for each transform block, which primary transform is to be applied in a horizontal direction and which primary transform is to be applied in a vertical direction.
10 . The image processing apparatus according to claim 9 ,
wherein the primary transform identifier indicates a first flag designating one of a plurality of transforms to be applied as the primary transform in the horizontal direction and indicating a second flag designating one of a plurality of transforms to be applied as the primary transform in the vertical direction.
11 . The image processing apparatus according to claim 10 ,
wherein the encoded data of the primary transform identifier comprises a binarization of the primary transform identifier and decoding of the primary transform identifier comprises performing inverse binarization of the binarized primary transform identifier.
12 . The image processing apparatus according to claim 11 ,
wherein the binarization of the primary transform identifier is a truncated unary binarization of the primary transform.
13 . An image processing method, comprising:
skipping, where a primary transform that is a transform process for a prediction residual that is a difference between an image and a prediction image of the image, a secondary transform that is a transform process for a primary transform coefficient obtained by the primary transform of the prediction residual, and quantization for a secondary transform coefficient obtained by the secondary transform of the primary transform coefficient are to be skipped, encoding of first information indicative of a substance of the primary transform.
14 . An image processing method, comprising:
skipping, where dequantization for a quantization transform coefficient level obtained by decoding encoded data, an inverse secondary transform for transforming a secondary transform coefficient obtained by the dequantization of the quantization transform coefficient level into a primary transform coefficient, and an inverse primary transform for transforming the primary transform coefficient into a prediction residual that is a difference between an image and a prediction image of the image are to be skipped, decoding of encoded data of first information relating to a substance of the inverse primary transform.