1. A computer-implemented method comprising: selecting an image out a plurality of images available for display on user devices, wherein the selected image is of a first resolution; determining that another version of the selected image is available, wherein the other version of the selected image is of a second resolution higher than the first resolution; updating the plurality of images available for display on user devices by adding the other version of the selected image to the plurality of images; generating a file containing instructions for displaying the updated plurality of images; determining a ratio of physical pixels to device-independent pixels of a display of a user device; and providing to the user device the file containing instructions and either the selected image or the other version of the selected image based on a comparison of the ratio of physical pixels to device-independent pixels of the display of the user device to a predetermined threshold value.