Other Formats:

Windows Bitmap (BMP) [& RLE]:

BMP files are saved without compression. RLE (Run Length Encoding) files are BMP with compression. They work well, but take up space. You will rarely see an RLE file as there are better methods for compression.

RS & RAS:

Raster graphics from Solaris® systems. The .rs extension is not always recognized in the Windows® environment. There are two solutions:

1. Change the extension from .rs to .ras and then most programs will recognize it.
2. Obtain a conversion program and convert it to a different format.

Guess which method I use!

PCX:

An old format with moderate compression. Rarely seen, but often used in older computer games, along with BMPs, for customizing icons and portraits.

etc.:

et cetera: There are many other formats, both esoteric and arcane, in the world of graphics, but that's what search engines are for.