This was made based on the wikipedia page on the flood fill algorithm: https://en.wikipedia.org/wiki/Flood_fill

If you have gcc and libpng-dev installed, you can compile the code by doing:

./compile.sh 

If you are on Debian, you can install libpng by doing:

sudo apt install libpng-dev

This is an implementation of the recursive version of the flood fill algorithm, so it is only feasible for usage with smaller images. test_img.png is a test file you can use.

For example, using the test image, you can do:

./flood_fill_png test_img.png 60 70 255 255 255 255 0 255 255 150 example_out.png

Which turns the test image from:

To:

flood_fill_png <png_in> <x_root> <y_root> <R> <G> <B> <A> <R_target> <G_target> <B_target> <A_target> <png_out>

Where:

• png_in : Input png image
• x_root : X coordinate to start filling from
• y_root : Y coordinate to start filling from
• R : Red value of target color to replace
• G : Green value of target color to replace
• B : Blue value of target color to replace
• A : Transparency value of target color to replace
• R_target : Red value to replace target color with
• G_target : Green value to replace target color with
• B_target : Blue value to replace target color with
• A_target : Transparency value to replace target color with
• png_out : Output file name