Sample sets and new down-sampling schemes for linear component sample prediction

A method for decoding images by deriving parameters of a linear model for obtaining a chroma sample of a target area from an associated luma sample of the target area, the method comprising:

• determining two pairs of values for determining the parameters of the linear model, each of the two pairs being defined by two variables, a first variable of the two variables corresponding to a luma sample, a second variable of the two variables corresponding to a chroma sample;
• determining the parameters of the linear model including a parameter corresponding to a slope of the linear model by using the two pairs of values;
• and
• decoding the target area using the parameters of the linear model,
• wherein a magnitude of the parameter corresponding to the slope is restricted so that a number of bits to represent the slope in integer arithmetic does not exceed 5 bits.

A device for encoding images by deriving parameters of a linear model for obtaining a chroma sample of a target area from an associated luma sample of the target area, wherein the device comprises:

• a deriving unit for deriving parameters of the linear model;
• a first determining unit for determining two pairs of values for determining the parameters of the linear model, each of the two pairs being defined by two variables, a first variable of the two variables corresponding to a luma sample, a second variable of the two variables corresponding to a chroma sample;
• a second determining unit for determining the parameters of the linear model including a parameter corresponding to a slope of the linear model by using the two pairs of values;
• and
• an encoding unit configured to encode the target area using the parameters of the linear model,
• wherein a magnitude of the parameter corresponding to the slope is restricted so that a number of bits to represent the slope in integer arithmetic does not exceed 5 bits.

A device for decoding images by deriving parameters of a linear model for obtaining a chroma sample of a target area from an associated luma sample of the target area, wherein the device comprises:

• a deriving unit for deriving parameters of the linear model;
• a first determining unit for determining two pairs of values for determining the parameters of the linear model, each of the two pairs being defined by two variables, a first variable of the two variables corresponding to a luma sample, a second variable of the two variables corresponding to a chroma sample;
• a second determining unit for determining the parameters of the linear model including a parameter corresponding to a slope of the linear model by using the two pairs of values;
• and
• a decoding unit configured to decode the target area using the parameters of the linear model,
• wherein a magnitude of the parameter corresponding to the slope is restricted so that a number of bits to represent the slope in integer arithmetic does not exceed 5 bits.

A non-transitory computer readable medium comprising executable code for a programmable apparatus, the executable code comprising a sequence of instructions for implementing a method for encoding images by deriving parameters of a linear model for obtaining a chroma sample of a target area from an associated luma sample of the target area, the method comprising:

• determining two pairs of values for determining the parameters of the linear model, each of the two pairs being defined by two variables, a first variable of the two variables corresponding to a luma sample, a second variable of the two variables corresponding to a chroma sample;
• determining the parameters of the linear model including a parameter corresponding to a slope of the linear model by using the two pairs of values;
• and
• encoding the target area using the parameters of the linear model,
• wherein a magnitude of the parameter corresponding to the slope is restricted so that a number of bits to represent the slope in integer arithmetic does not exceed 5 bits.

A non-transitory computer readable medium comprising executable code for a programmable apparatus, the executable code comprising a sequence of instructions for implementing a method for decoding images by deriving parameters of a linear model for obtaining a chroma sample of a target area from an associated luma sample of the target area, the method comprising:

• determining two pairs of values for determining the parameters of the linear model, each of the two pairs being defined by two variables, a first variable of the two variables corresponding to a luma sample, a second variable of the two variables corresponding to a chroma sample;
• determining the parameters of the linear model including a parameter corresponding to a slope of the linear model by using the two pairs of values;
• and
• decoding the target area using the parameters of the linear model,
• wherein a magnitude of the parameter corresponding to the slope is restricted so that a number of bits to represent the slope in integer arithmetic does not exceed 5 bits.