Transform-based image coding method and device therefor
AssigneeLG Electronics Inc.
InventorsMoonmo KOO, Seunghwan KIM, Jaehyun LIM
Life of this patent
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Abstract
An image decoding method according to the present document may comprise the steps of: receiving, at a general restriction information level, a restriction flag for restricting whether to perform a non-separable inverse transform in a low frequency area of a transform block; receiving, at a sequence parameter set level, an activation flag indicating whether to activate the non-separable inverse transform; parsing a transform index used for the non-separable inverse transform, on the basis of the restriction flag and the activation flag; and performing the non-separable inverse transform on the transform block on the basis of the transform index.
Claims14
An image decoding method performed by a decoding apparatus, the method comprising:
- receiving a constraint flag for restricting whether to perform a non-separable inverse transform for a low frequency region of a transform block at a general constraint information level;
- receiving an activation flag related to whether to activate the non-separable inverse transform at a sequence parameter set level;
- parsing a transform index used for the non-separable inverse transform based on the constraint flag and the activation flag;
- and
- performing the non-separable inverse transform on the transform block based on the transform index.
An image encoding method performed by an image encoding apparatus, the method comprising:
- encoding a constraint flag for restricting whether to perform a non-separable transform for a low frequency region of a transform block at a general constraint information level;
- encoding an activation flag related to whether to activate the non-separable transform at a sequence parameter set level;
- performing the non-separable transform for the low frequency region to derive transform coefficients;
- encoding a transform index related to a transform matrix used for the non-separable transform based on the constraint flag, the activation flag, and whether the non-separable transform is performed;
- and
- outputting the constraint flag, the activation flag, the transform index, and residual information on the transform coefficients.
A method for transmitting data for image information comprising:
- encoding a constraint flag for restricting whether to perform a non-separable transform for a low frequency region of a transform block at a general constraint information level;
- encoding an activation flag related to whether to activate the non-separable transform at a sequence parameter set level;
- performing the non-separable transform for the low frequency region to derive transform coefficients;
- encoding a transform index related to a transform matrix used for the non-separable transform based on the constraint flag, the activation flag, and whether the non-separable transform is performed;
- and
- outputting the constraint flag, the activation flag, the transform index, and residual information on the transform coefficients.
Dependencies are inferred from the claim text.