XV is an interactive image viewer for the X Window System. The XV program displays images in the GIF, JPEG, TIFF, PNG, PBM, PGM, PPM, X11 bitmap, Utah Raster Toolkit RLE, PDS/VICAR, Sun Rasterfile, BMP, PCX, IRIS RGB, XPM, Targa, XWD, possibly PostScript, and PM formats on workstations and terminals running the X Window System, Version 11.
The XV program is also capable to manipulate pictures. It can zoom in and out of picture, and rotate and flip them. It also provides a wide variety of operations to modify colors.
Surley, one of the most famous programs under Linux.
You will find the documentation in /usr/doc/packages/xv/.
Please remember that this program has shareware status for commercial use.