Abstract: A method, an image processing device, and a display system for power-constrained image enhancement are proposed. The method is applicable to an image processing device and includes the following steps. First, an input image is received and inputted into a power-constrained sparse representation (PCSR) model, where the PCSR model is associated with a sparse representation model and a power-constraint model, where the sparse representation model is associated with an over-complete dictionary and sparse codes, and where the power-constrained model is associated with pixel intensities of the input image and a gamma correction value of a display Next, a reconstructed image outputted by the PCSR model is obtained and displayed on the display.