BatchConverter 2.1 is a conversion program with which you get a wide range of graphic formats between which to convert.
It has the most popular like GIF, JPG, PNG, BMP, PSD or TIF, and less common ones like PSP, BW, RGB, SGI, CEL, PIC, TGA, VST, ICB, VDA, WIN, PCX, PCC, SRC, PPM, PCD, PGM, PBM, CUT, PAL, RLA, RPF, RLE o DIB.
It also has a graphic utility to add discrete text over the photos (ideal to do watermarks, copyright or contact information).