PNG

PNG (Portable Network Graphic) is a great alternative to the GIF and JPEG formats. PNGs compress bitmaps without loss while supporting transparency and True Color. You can save a photo-quality image as a PNG without losing image information or color. In the Save As dialog, you can set the background color as transparent. The background color refers to the color set on the Tool Settings Panel, not necessarily the actual background color of your image.

Save a PNG image with a transparent background color