Random Quad-Thread Weaver 4k (No AI)

The algorithm works like this:

• Pick a color and set a pixel to this color.
• Repeat step 1 as many times as desired.
• Pick a color.
• Find the colored edge pixel closest in color to this color.
• Set one of its uncolored 8-adjacent pixels to this color.
• Go to step 3 unless all pixels have been colored.

Command line used:

 ./color -o4096x4096x8_4-starts.ppm -s4096:4096:8 -p0,0 -p4095,0 -p0,4095 -p4095,4095

Generated with C code (Public Domain) from Christopher Wellons:

github.com/skeeto/every-rgb