Any image that has a pixel with an RGB value matching exactly as the color you specify will be made completely transparent. Windows users should notice that WIN+SHIFT+S (snipping tool) has a color picker tool. Thanks to whoever uploaded non-transparent sprites to Spriters Resource. Hex code will only update if the entry input looks like #11FFAA. PLEASE ENTER THE COLOR FIRST SINCE IMAGES ARE IMMEDIATELY PROCESSED ON UPLOAD (sorry about that)