Xloadimage is a utility which will view many different types of images under X11, load images onto the root window, or dump processed images into one of several image file formats. The current version can read many different image file types.
A variety of options are available to modify images prior to viewing. These options include clipping, dithering, depth reduction, zoom (either X or Y axis independently or both at once), brightening or darkening, and image merging. When applicable, these options are done automatically (eg a color image to be displayed on a monochrome screen will be dithered automatically).