Moving image coding device and method using chrominance format and intra-frame prediction mode
View Patent ↗The present invention includes: a CCLM prediction derivation portion, for deriving a first parameter and a second parameter by using a sampled luminance value downsampled according to a chrominance format and an intra-frame prediction mode; and a CCLM prediction filter portion, for deriving a prediction image by using the first parameter and the second parameter, wherein the CCLM prediction derivation portion derives the first parameter by deriving a logarithmic value of a luminance difference value, deriving a first value by right-shifting a second value related to the luminance difference value by the logarithmic value, and using a third value acquired by multiplying a fourth value by a chrominance difference value and derives the second parameter by using the first parameter. The fourth value is determined from a reference table by using the first value.
1. A moving image decoding device for generating a prediction image by using an intra-frame prediction mode, the moving image decoding device comprising:
at least one processor; and
at least one storage device coupled to the at least one processor and storing computer- executable instructions which, when executed by the at least one processor, cause the moving image decoding device to:
derive a first parameter and a second parameter by using a sampled luminance value downsampled according to a chrominance format and the intra-frame prediction mode; and
derive the prediction image by using the first parameter and the second parameter, wherein:
the first parameter is derived by
deriving a logarithmic value of a luminance difference value,
deriving a first value by right-shifting a second value related to the luminance difference value by the logarithmic value, and
using a third value acquired by multiplying a fourth value by a chrominance difference value, wherein the fourth value is determined from a reference table by using the first value, and
the second parameter is derived by using the first parameter.
2. The moving image decoding device according to claim 1 , wherein
the luminance difference value is a difference value between a first sampled value and a second sampled value, and
the chrominance difference value is a difference value between a third sampled value and a fourth sampled value.
3. The moving image decoding device according to claim 2 , wherein:
the second parameter is derived by subtracting a fifth value from the first sampled value, and
the fifth value is acquired by right-shifting a product of the first parameter and the first sampled value by a first shift value.
4. The moving image decoding device according to claim 3 , wherein the prediction image is derived by right-shifting a product of the first parameter and a sampled luminance value by the first shift value and then adding the second parameter to the right-shifted product.
5. The moving image decoding device according to claim 1 , wherein the first parameter is derived by right-shifting the third value by a value related to a chrominance bit depth.
6. The moving image decoding device according to claim 1 ,
wherein an encoding object image is restored by adding a residual image to or subtracting the residual image from the prediction image.
7. A moving image encoding device for generating a prediction image by using an intra-frame prediction mode, the moving image encoding device comprising:
at least one processor; and
at least one storage device coupled to the at least one processor and storing computer- executable instructions which, when executed by the at least one processor, cause the moving image encoding device to:
derive a first parameter and a second parameter by using a sampled luminance value downsampled according to a chrominance format and the intra-frame prediction mode; and
derive the prediction image by using the first parameter and the second parameter, wherein:
the first parameter is derived by
deriving a logarithmic value of a luminance difference value,
deriving a first value by right-shifting a second value related to the luminance difference value by the logarithmic value, and
using a third value acquired by multiplying a fourth value by a chrominance difference value, wherein the fourth value is determined from a reference table by using the first value, and
the second parameter is derived by using the first parameter.
8. The moving image encoding device according to claim 7 ,
wherein a residual image of the prediction image and an encoding object image are encoded.
9. A prediction image generation method for generating a prediction image by using an intra-frame prediction mode, the prediction image generation method comprising:
deriving a first parameter and a second parameter by using a sampled luminance value downsampled according to a chrominance format and the intra-frame prediction mode; and
deriving the prediction image by using the first parameter and the second parameter, wherein:
the first parameter is derived by
deriving a logarithmic value of a luminance difference value,
deriving a first value by right-shifting a second value related to the luminance difference value by the logarithmic value, and
using a third value acquired by multiplying a fourth value by a chrominance difference value, wherein the fourth value is determined from a reference table by using the first value, and
the second parameter is derived by using the first parameter.