This utility will view several types of images under X11, or load
images onto the root window.  The current version supports:
     Native Image File Format (NIFF)
     Sun Rasterfile
     GIF Image
     JFIF-style JPEG Image
     Portabel Network Graphics (PNG)
     TIFF image
     FBM Image
     CMU WM Raster
     Portable Bit Map (PBM, PGM, PPM)
     Faces Project
     Utah RLE Image
     X Window Dump
     Sun Visualization File Format
     McIDAS areafile
     VICAR Image
     PC Paintbrush Image
     GEM Bit Image
     MacPaint Image
     X Pixmap
     X Bitmap
A variety of options are available to modify images prior to viewing.
These options include clipping, dithering, depth reduction, zoom,
brightening or darkening, and image merging.