file.css

img[src$=".gif"],
img[src$=".png"] {
	image-rendering: -moz-crisp-edges;         /* Firefox */
	image-rendering:   -o-crisp-edges;         /* Opera */
	image-rendering: -webkit-optimize-contrast;/* Webkit (non-standard naming) */
	image-rendering: crisp-edges;
	-ms-interpolation-mode: nearest-neighbor;  /* IE (non-standard property) */
}