Color Graph Readme

Author: Jeffery Wright

Version 0.0.1

Color Graph is an attempt to generalize previous little programs I've 
written that use the ASCII version of the Portable Pixelmap format to 
generate images based on some numerical pattern. All previous programs 
I've written in this vein hardcoded everything, so changing the image 
generated required editing the source code and recompiling.

This initial public version has the following features:

*Lets the user set a base filename for the output(the .ppm filename 
extension is added automatically).

*Lets the user select the height and width of the output images.

*Generates a set of 4 images based on the following equations:


r = ax + by + c

g = ax + by + c

b = ax + by + c

With one image for each color individually and one for the three 
combined. The component images are named with their color appeneded to 
the end of the user selected filename.

*Lets the user select the x and y coefficients for each color channel as 
well as the constant(referred to as the baseline in the program's 
prompts). At present, these are restricted to integer values.

*Evaluates the equations for each integer ordered pair(x,y) using half 
of the height and width for the positive and negative limits. If Height 
and Width are even, the lines x=0 and y=0 are skipped. Future versions 
might replace these predetermined bounds calculated from height and 
width with user selected bounds and calculating height and width from 
bounds.

*A text-based interface that prompts the user for each parameter and 
accepts keyboard input.

*Keeps output in the right range by taking the absolute value of the 
equations to keep subpixel values positive and taking the modulus 256 to 
keep values from getting too large.

Files available to the public include:

Readme.txt: This readme.

ColorGraph.cpp: the source code.

ColorGraph-0.0.1.bin: A binary executable compiled on Debian Testing 
amd64 using g++ version 13.

A smattering of optimized .png files converted from .ppm files generated 
as a test of the program.

I have only tested this program on 64-bit Debian, but have no reason to 
expect issues compiling and running on other versions of Debian, other 
distros of Linux, any version of Windows, or on MAC OSX. At the same 
time, I can offer no advice for compiling on anything other than a Linux 
box and have no idea how to cross-compile for Windows or OSX.

Also, due to being blind, my ability to test is limited. I can confirm 
the program compiles, runs, prints the correct user prompts, accepts 
reasonable inputs, and outputs valid Portable Pixelmap files, but I can 
say very little about the actual contents of the output files.

You will need external software to either view the output files or 
convert them to a more widely supported format. As the files are 
ASCII-based, they can be viewed in a text editor, but all you'll see is 
a super short header followed by a bunch of RGB triplets printed as 
space delimited decimal numbers, one pixel per line. Fellow Linux users 
can use optipng to convert the output files to optimized png files, but 
I don't know if optipng is available for Windows or OSX, so non-Linux 
users are on their own. All of my programmatically generated images were 
converted using optipng with the -o7 preset.

Features I hope to implement soon:

*the option to apply a mask that cancels out a color if it isn't 
divisible by a user defined value. Masking red by 2, green by 3, and 
blue by 5 is in the code, though commented out for the pre-built binary, 
so it's mostly a matter of adding the prompts to the user.

*The ability to pick from more than one kind of equation. The most 
obvious choice would be to optionally take the absolute value of ax or 
by or to allow for quadratic or cubic terms.

*Implement the option to generate multiple images that could then be 
joined into an animation.

*Implementing an output file that stores the parameters used in a human 
readable format.

Features that are more long term projects in their own right:

*A better interface.

*Being able to input any equation, even one with non-integer outputs.

*Drawing traditional cartesian, parametric, and polar graphs over the 
color graph.

*Adding alpha channels to images and generating voxel graphics.