		STANDARD FORMATS FOR DIGITIZED IMAGE FILES
		==========================================

*.pix	Standard file.  Consists of a byte stream.  Format described in
	pix.format.

*.asc	Same as pix, but each byte value is written out in decimal.  That is,
	to make one, instead of doing
		putchar (byte)
	for each byte in the stream, you do
		printf ("%d3.0\n", byte)
	Since this format causes about a 4-fold expansion in the file's size,
	it is really only useful for debugging or for FTPing files around.

*.sun	Image file for loading directly into a sun graphics buffer with the
	photo program.  Format described in sun.format.

*.pic	Used only on Sail.  A format which the pix program there uses;
	unfortunately it is a 36-bit format, and so doesn't FTP very well.
	Described in pic.format.

*.xgp	Used only on sail.  A "text" file which uses a special font, is is
	suitable for XSPOOLing.

*.tty	A file which can be typed directly on an upper/lower case tty.

*.lpt	A file which can be send directly to a line printer.  Note that this
	is NOT the same as *.tty, since lpt files can (and do) use
	overprinting.


		CONVERSION PROGRAMS
		===================

	Programs named foobar take an input file in the foo format and produce
output in the bar format.  Thus picasc on sail is the appropriate thing to use
to snatch a pic file.  Then you ftp the asc file to a vax, where you can run
ascpix to shrink it back to normal size.


		OTHER PROGRAMS
		==============

ALL other (i.e. non-conversion) programs expect both input and output to be in
the pix format.  They can process the image in any desired way.  Some
examples are "expand", which increases the size of an image, and "avgerror",
which halftones an image.
