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.