A method of transcoding web images. The method comprises determining a mean opinion score (MoS) for a test source digital image, transcoding the test source digital image to a test derived digital image, and determining a MoS for the test derived digital image presented on a standard display. The method further comprises receiving a source digital image by a server computer, where the source digital image is requested by a device for presentation on a target display, transcoding the source digital image to a derived digital image by a transcoding application executed by the server computer, determining an estimated MoS for the derived digital image based on the MoS for the test source digital image, based on the MoS for the test derived digital image, and based on differences between the standard display and the target display, and changing a parameter of the transcoding application based on the estimated MoS.