Patent ID: 7715649
Filing Date: 2010-05-11
Classification: H04N

Abstract:
1. An apparatus for creating a luminance conversion curve, comprising: a main subject image portion partitioning device for partitioning a main portion of an image of a subject from an image represented by applied image data; a main subject image luminance value calculating device for calculating a representative luminance value of the main portion of the image of the subject partitioned, and a dynamic range that stipulates a bright luminance value and a dark luminance value of the main portion of the image of the subject partitioned; a target luminance value setting device for setting a target representative luminance value prevailing after luminance correction of the representative luminance value, as well as a target dynamic range that stipulates a target bright luminance value prevailing after luminance correction of the bright luminance value and a target dark luminance value prevailing after luminance correction of the dark luminance value; a luminance conversion curve calculating circuit for calculating a luminance conversion curve, which stipulates output luminance values versus input luminance values, based upon the representative luminance value and dynamic range calculated by said main subject image luminance value calculating device and the target representative luminance value and target dynamic range set by said target image luminance value setting device; a main subject image saturation predicting device for calculating a predicted saturation of the main subject image in a case where a luminance correction has been applied to the applied image data, based upon the luminance conversion curve calculated by said luminance conversion curve calculating circuit; a range width narrowing device for narrowing range width of the target dynamic range if the predicted saturation of the luminance-corrected main subject image calculated by said main subject image saturation predicting device exceeds an upper-limit saturation calculated based upon the target representative luminance value set by said target luminance value setting device; a target dynamic range revising device for revising the target dynamic range so as to have the range width narrowed by said range width narrowing device; and a luminance conversion curve revising device for revising the luminance conversion curve using the target dynamic range revised by said target dynamic range revising device, wherein said target dynamic range revising device revises the target dark luminance value and target bright luminance value, whereby the target dynamic range after revision will come to have a range width that has been narrowed by said range width narrowing device; and revises the target bright luminance value and target dark luminance value such that ratio of the range width between the target representative luminance value and target dark luminance value to the range width of the dynamic range will agree with the ratio of the range width between the target representative luminance value and revised target dark luminance value to the range width of the revised target dynamic range, and such that the ratio of the range width between the target representative luminance value and target bright luminance value to the range width of the target dynamic range will agree with the ratio of the range width between the target representative luminance value and revised target bright luminance value to the range width of the revised target dynamic range.