README.md

Split By Color

A simple C program to cut ppm images along a line identified by two green dots. It is a utility to be integrated in the InsomniaLab DIY bookscanner.

To compile

Simply use make. To compile

make all

To clean

make clean

How to use

./split -f .ppm

The code is fairly commented. The code to read and write the PPM is taken from an example in stackoverflow (http://stackoverflow.com/questions/2693631/read-ppm-file-and-store-it-in-an-array-coded-with-c).

Debug

• threshold(int green, int red, int blue) [lib/manppm.c]

This is the function that tests the color of any pixel that is passed. The logic is the simplest: to pass the test the color should be into the interval

green<=greenT red>=redT blue<=blueT

The three constants (greenT,redT,blueT) are defined in lib/ppm_common.h

To stress or test the threshold function in lib/manppm.c you can change the definition at compile time with

make EXTRACFLAGS="-D greenT=new_green_value -D redT=new_red_value -D blueT=new_blue_value" all

TO DO:

• Integrate with ppmrose (https://aur.archlinux.org/packages/ppmrose) to perform the unwarping
• Test with real book scanner images (in progress)
• A LOT of debug!