A device, computer-readable medium or method for adjusting pixels of a source image prior to being output to a display device comprising: segmenting the pixels of the source image into spatial groups; assigning an adjustment method to each pixel in a group; creating an adjustment matrix set with rows (or columns) corresponding to the plurality of adjustment methods, and columns (or rows) corresponding to a range of pixel values that exceed a discrete output device value, and adjustment values as entries; receiving a pixel of the source image in a graphics processing unit (GPU) and using the GPU to: determine the pixel's relative location in its spatial group and its corresponding adjustment method; determine the range of pixel values that the value of the pixel exceeds a discrete output device value: select an adjustment value from the adjustment matrix set; and adjust the value of the pixel by the adjustment value.