A method for transforming an image to adjust image contrast locally within a sub-area of an image for display by a display device comprising: calculating a tone curve which maps luminance levels of the original image, wherein said calculating the tone curve includes determining the tone curve that optimizes a match between a contrast of said original image and a contrast of said image having transformed luminance levels; and transforming luminance levels of the original image according to the tone curve to provide a transformed image having transformed luminance levels, and extracting a base band image from the transformed image; decomposing the original image into an image pyramid which comprises a plurality of different component images which each represent said image via spatial frequencies within a respective one of a plurality of different spatial frequency bands; for some or each component image, calculating a respective contrast adjustment factor for adjusting a contrast within a sub-area of the component image and transforming a contrast within the sub-area of the component image according to the contrast adjustment factor, wherein calculating the contrast adjustment factor includes determining a measure of local contrast within said sub-area and therewith determining a contrast adjustment factor that optimises a match between said contrast of said original component image and said contrast of said transformed component image, wherein said contrast adjustment factor is determined such that the difference between the value of the measure of local contrast (c) and the value of the product ( c × m) of the measure of local contrast and the adjustment factor ( m) matches the difference between a contrast detection threshold value for the transformed component image and a contrast detection threshold value for the original component image, wherein said contrast detection threshold value for said original component image and said transformed component image is defined by a predetermined contrast sensitivity function which is a function of peak frequency corresponding to the given spatial frequency band and luminance of the original image and luminance of the base-band image derived from the transformed image; and recomposing a transformed image from a plurality of the transformed component images, wherein the component image associated with the lowest spatial frequencies is substituted with the base-band image derived from the transformed image. calculating a tone curve which maps luminance levels of the original image, wherein said calculating the tone curve includes determining the tone curve that optimizes a match between a contrast of said original image and a contrast of said image having transformed luminance levels; and transforming luminance levels of the original image according to the tone curve to provide a transformed image having transformed luminance levels, and extracting a base band image from the transformed image; decomposing the original image into an image pyramid which comprises a plurality of different component images which each represent said image via spatial frequencies within a respective one of a plurality of different spatial frequency bands; for some or each component image, calculating a respective contrast adjustment factor for adjusting a contrast within a sub-area of the component image and transforming a contrast within the sub-area of the component image according to the contrast adjustment factor, wherein calculating the contrast adjustment factor includes determining a measure of local contrast within said sub-area and therewith determining a contrast adjustment factor that optimises a match between said contrast of said original component image and said contrast of said transformed component image, wherein said contrast adjustment factor is determined such that the difference between the value of the measure of local contrast (c) and the value of the product ( c × m) of the measure of local contrast and the adjustment factor ( m) matches the difference between a contrast detection threshold value for the transformed component image and a contrast detection threshold value for the original component image, wherein said contrast detection threshold value for said original component image and said transformed component image is defined by a predetermined contrast sensitivity function which is a function of peak frequency corresponding to the given spatial frequency band and luminance of the original image and luminance of the base-band image derived from the transformed image; and recomposing a transformed image from a plurality of the transformed component images, wherein the component image associated with the lowest spatial frequencies is substituted with the base-band image derived from the transformed image.