1. A computer-implemented method for image adaptation, comprising: accepting a digitally-represented input image; accepting a target size requirement; and modifying the input image by reducing at least one of a resolution of the input image and a quality of the input image, the quality defining an amount of information allocated to represent each pixel value of the input image, so as to produce a compressed output image meeting the target size requirement, wherein accepting the input image comprises accepting a minimum tolerable quality requirement, and wherein modifying the input image comprises reducing the quality of the input image while meeting the minimum tolerable quality requirement, and reducing the resolution of the input image only when reducing the quality of the input image while meeting the minimum tolerable quality requirement does not meet the target size requirement.