Converting an image into an output image having a higher dynamic range

An image processing device for converting an input image having a first dynamic range into an output image having a second dynamic range higher than the first dynamic range, the image processing device comprising:

• at least one processor configured to transform an input luminance value associated with a pixel of the input image into an output luminance value associated with the corresponding pixel in the output image,
• wherein the at least one processor is configured to apply a continuous and increasing function mapping a first range of values into a second range of values, whereby the highest value in the first range of values is mapped by the continuous and increasing function into a supremum of the second range of values,
• wherein the at least one processor is configured to determine a peak luminance as a function of a plurality of pixel values of the input image by evaluating a measure of brightness of the input image and determining the peak luminance as a function of said measure of brightness, the peak luminance decreasing as a function of said measure of brightness, and
• wherein the at least one processor is configured to adjust the supremum depending on the peak luminance.