1. Image encoder comprising: a color space converter configured to transform device dependent floating point image data to device independent floating point image data, wherein the device dependent floating point image data includes values of three floating point parameters for each pixel and the device independent floating point data includes a floating point luminance image value and two floating point chrominance image values for each pixel; an extreme value determiner configured to determine a minimal value and a maximal value of the floating point luminance image value of each pixel of a part of an image, an image or a group of images; a floating point-to-integer converter configured to implement an adaptive floating point-to-integer mapping, wherein only the floating point luminance image value of each pixel is adaptively mapped to an integer luminance image value, wherein each integer luminance image value lies in a predefined range of integer luminance image values, while the chrominance image values for each pixel are non-adaptively mapped, wherein the determined minimal floating point luminance image value is mapped to a minimal integer luminance image value of the predefined range of integer luminance image values and the determined maximal floating point luminance image value is mapped to a maximal integer luminance image value of the predefined range of integer luminance image values, wherein the floating point-to-integer converter is configured to calculate at least one transform parameter for the part of the image, the image or the group of images based on the determined minimal floating point value and the determined maximal floating point value, wherein the floating point value of each pixel of the part of the image, the image or the group of images is mapped based on the transform parameter; and an encoder configured to encode the integer luminance image value of each pixel to acquire and provide encoded image data of the part of the image, the image or the group of images, wherein the transform parameter is provided with the encoded image data of the part of the image, the image or the group of images.