MUMBAI, India, Sept. 22 -- Intellectual Property India has published a patent application (202647101812 A) filed by Koninklijke Philips N. V. on August 24, 2026, for Luminance Mapping For Images.
Inventor includes Tichelaar, Johannes Yzebrand.
The application for the patent was published on September 18, 2026, under issue no. 38/2026.
Abstract: To obtain better color control in dynamic range mappings, which are e.g. useful in particular for HDR image coding and communication, the inventor proposes a luminance down-mapper (500) and corresponding up-mapper comprising: a luma input (501) for a normalized input luma (Y'_i) which codes an input luminance lying within a first luminance dynamic range (DR_H); a chroma input (502) for two normalized input chroma components (Cb, Cr_i), which together with the input luma define an input color (C_H); a supply circuit (503) arranged to supply a set of multipliers (g1(X'1); g2(X'2)) of respective normalized input values (X'1; X'2) spanning a range of normalized input values, which is arranged to determine the set of multipliers based on a luma mapping function (F_LBri), by calculating for any one of the respective normalized input values a respective output value resulting from applying the luma mapping function to the respective normalized input value, and calculating the respective multiplier as the result of dividing the respective output value by the respective input value; a first multiplier determination circuit (504) arranged to output a first multiplier (gd(Y')) from the set of multipliers which corresponds to an input value equal to the normalized input luma; a largest primary color component determining circuit (506) arranged to determine the largest component (LC_i) of a red, green and blue color component representation of the input color; a second multiplier determination circuit (507) arranged to output a second multiplier (gd(LC)) from the set of multipliers which corresponds to an input value equal to the largest component (LC_i); a weight determination circuit (508) arranged to receive a control parameter (Ksi) from a source (509), and to output a first weight (A) and a second weight equal to one minus the first weight (1- A), wherein the first weight is calculated, for non-zero values of the input luma, as the minimum of the value one and a first result, wherein the first result equals a multiplication of the control parameter by a second result, wherein the second result is obtained by subtracting the value one from a third result; wherein the third result is obtained by dividing the largest component (LC_i) by the input luma (Y'_i); a first multiplication circuit (510) arranged to obtain a first weighted multiplier (gd_W) as the result of multiplying the first multiplier (gd(Y')) by the second weight (1-A); a second multiplication circuit (511) arranged to obtain a second weighted multiplier (gd_LCW) as the result of multiplying the second multiplier (gd(LC)) by the first weight (A); an adder (512) to yield a final multiplier (gF) by adding the first weighted multiplier (gd_W) to the second weighted multiplier (gd_LCW); a third multiplication circuit (513) to yield a normalized output luma by multiplying the input luma by the final multiplier (gF), and a fourth multiplication circuit (514) to yield two normalized output chroma components by multiplying the two normalized input chroma components (Cb, Cr_i) by the final multiplier (gF).
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