Patent ID: 8982963
Filing Date: 2015-03-17
Classification: G06F,G06T,G09G,H04N

Abstract:
1. A method for generating inverse tone mapping parameters, comprising: receiving a first image stream of a first dynamic range and of a first color space and a second image stream of a second dynamic range in a layered codec; wherein: the first dynamic range is lower than the second dynamic range; the first image stream is in a base layer and the second image stream is in an enhancement layer; and the layered codec comprises a decoder and an encoder; and encoding the first image stream in the base layer using the encoder to obtain an encoded image stream; decoding the encoded image stream using the decoder to obtain a decoded image stream; converting the decoded image stream from the first color space to a second color space different from the first color space to obtain a color converted image stream; and for each of a plurality of pixels of an image of the decoded color converted image stream, generating a respective single inverse tone mapping parameter that parameterizes a tone mapping function of the log luminance of a pixel of the decoded color converted image stream, wherein the tone mapping function comprises a quadratic function of the log luminance of a pixel of the decoded color converted image stream, the quadratic function providing a mapping for the single inverse tone mapping parameter, and wherein the respective single inverse tone mapping parameter is selected wherein the tone mapping function outputs an approximation of the log luminance of a corresponding pixel of the second image stream; and wherein the respective single inverse tone mapping parameter is μ, the log luminance of a pixel of the decoded color converted image stream is L