Inverse tone mapping with adaptive bright-spot attenuation

A device for converting a current image in a standard dynamic range into an output image in a high dynamic range, wherein the device comprises electronic circuitry adapted for:

• obtaining an initial gain function of a first inverse tone mapping function;
• obtaining a target luminance value;
• and
• responsive to at least a pixel of the current image with a luminance value at least equal to the target luminance value having an expanded luminance value resulting from an application of the first inverse tone mapping function to the current image higher than a target expanded luminance value, applying a second inverse tone mapping function to the current image to obtain the output image, the second inverse tone mapping function corresponding to the first inverse tone mapping function in which the gain function has been replaced by a modified gain function, the modified gain function being a function derived from the initial gain function in which a gain provided by the initial gain function is attenuated by an attenuation function, said attenuation function being an increasing function of luminance values weighted by a weighting factor controlling a strength of the attenuation, the weighting factor being determined by browsing a statistical distribution of luminance values in an histogram of the current image between a maximum luminance value and the target luminance value in descending order of luminance values from the maximum luminance value, computing an intermediate weighting factor for each browsed luminance value while the browsed luminance value is at least equal to the target luminance value and on a result of an application of the first inverse tone mapping function to the browsed luminance value is at least equal to the target expanded luminance value, and setting the value of the weighting factor to a value corresponding to a maximum of the computed intermediate weighting factor;
• otherwise, applying the first inverse tone mapping function to the current image to obtain the output image.