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US 2026/0212471 A1Published application
Image processing apparatus and image processing method
AssigneeKoninklijke Philips N.V.
InventorJohannes Yzebrand Tichelaar
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Abstract
An image processing apparatus (1) is provided that comprises a luminance calculation circuit (2) and a luminance mapper (3). The luminance calculation circuit (2) to calculate an input luminance (Li) from non-linear color components (R′, G′, B′) that specify an input color and the luminance mapper (3) is configured to apply a luminance mapping function to the input luminance (Li) to obtain an output luminance (Lo). The luminance calculation circuit (2) computes relative accurate approximation of the input luminance in a computationally efficient manner.
Claims21
An apparatus comprising:
- a luminance calculation circuit;
- and
- a luminance/luma mapper circuit,
- wherein the luminance calculation circuit is arranged to compute an output value as a function of a first input value and a second input value,
- wherein the function selects the first input value if the first input value is larger or equal to the second input value,
- wherein the function selects the second input value if the second input value is greater than the first input value,
- wherein the non-selected one of the first input value and the second input value is a secondary value,
- wherein the function computes the output value as a linear weighting of the primary value and the secondary value if the primary value is less than a product of the secondary value with a constant,
- wherein the function determines the primary value as the output value if primary value is greater or equal to product of the secondary value with a constant,
- wherein the luminance calculation circuit is arranged to apply the function to compute a first intermediate output value using a first intermediate color component and a second intermediate color component,
- wherein the luminance calculation circuit is arranged to apply the function to compute a second intermediate value using the first intermediate output value and a third intermediate color component,
- wherein an input luminance as a power of the second intermediate value,
- wherein the luminance/luma mapper circuit is arranged to obtain an output luminance/luma using the second intermediate value,
- wherein the first intermediate color component, the second intermediate color value and the third intermediate color value are being respective weighted values of a first non-linear input color component, a second non-linear input color component and a third non-linear input color component respectively,
- wherein the respective weights are characteristic for a primary video coding system.
12 more elements
A method comprising:
- calculating an input luminance from non-linear color components;
- applying a luminance/luma mapping function to the input luminance to obtain an output luminance/luma after calculating the input luminance,
- wherein calculating the input luminance comprises:
- computing an output value as a function of a first input value and a second input value,
- wherein the function selects the first input value if the first input value is larger or equal to the second input value,
- wherein the function selects the second input value if the second input value is greater than the first input value,
- wherein the non-selected one of selects the other one of the first input value and the second input value is a secondary value,
- wherein the function computes the output value as a linear weighting of the primary value and the secondary value if the primary value is less than a product of the secondary value with a constant,
- wherein the function determines the primary value as the output value if primary value is greater or equal to product of the secondary value with a constant;
- applying the function to compute a first intermediate output value using a first intermediate color component and a second intermediate color component;
- subsequently applying the function to compute a second intermediate value using the first intermediate output value and a third intermediate color component,
- calculating the input luminance as a power of the second intermediate value;
- and
- calculating an output luminance/luma using the second intermediate value,
- wherein the first intermediate color component, the second intermediate color value and the third intermediate color value are being respective weighted values of a first non-linear input color component, a second non-linear input color component and a third non-linear input color component respectively,
- wherein the respective weights that are characteristic for a primary video coding system.
13 more elements
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Dependencies are inferred from the claim text.