The present invention relates to an image processing system, method and computer program for contrast enhancement of images, and more specifically to an improvement of multi-scale adaptive gain control of images. An image processing system (1) for contrast enhancement of an input image is proposed comprising an input module (2) for receiving the input image to be processed, a filtering module (4) operable to locally process the input image by filters of different scales k, whereby for each of the different scales k a locally processed image data and at least one statistic value LSD corresponding to the locally filtered image data is generated, a combining module (5) operable to locally combine the processed image data of the different scales k using a gain function G, thereby generating a contrast enhanced image o, wherein the gain function G is dependent on the statistic value LSD corresponding to the locally processed image data of the respective scale k, and an output module (3) for outputting the contrast enhanced image whereby the gain function G comprises at least one further local dependent correction term a; b; c; d in order to suppress artefacts in the contrast enhanced image.