Karl Thomas Rees
December 8, 2000
Readme File for HW#10

Compression/Encoding

For this assignment, I wrote two programs.  One encodes a .pgm image,
 while the other decodes it (using a modified JPEG lossless algorithm).
The files and their calling syntax are: 

	./encode in.pgm out.pgm inhist.dat outhist.dat
	./decode in.pgm out.pgm

(The inhist.dat and outhist.dat are plot files containing
the histogram of the image read and the image outputted
respectively).

I came up with the following results:

compact parrots.pgm (no encoding) 98K -> 90K
compact eparrots.pgm (encoding) 98K-> 52K

The histograms for the parrots.pgm and the encoded version of that
image looked like this:














The encode/compact/decompact/decode sequence produced the exact
same image that I started with (see files parrots.pgm, eparrots.pgm, 
eparrots.pgm.jz, dparrots.pgm.jz, dparrots.pgm) for proof of this
process. 

Here are the results for five other files I tried:

FILE			SIZE		COMPACT		ENCODE & COMPACT
---------		-----		-------		----------------
ball.pgm		65K		56K (1.16:1)	19K (3.4:1)
gull.pgm		65K		47K (1.38:1)	45K (1.44:1)
mystery.pgm		262K		158K (1.65:1)	200K (1.31:1)
chinese_chars.pgm	28K		8K (3.5:1)		13K (2.15:1)
linux.pgm		49K		41K (1.2:1)		22K (2.23:1)