handy function for converting high-res whiteboard sketches to crisp, transparent background PNGs. Thanks for the wicked-awesome Marciana drawing, Monica ;)
Super easy:
- clone this repo
cd transparent-pngpip install -r requirements.txt- To test:
python converter.py
Here's the result you should get:
Here's a more fully-feature version. This works best on whiteboard sketches where the target colors are very consistent, but the visual effect is cool nonetheless:
python converter.py --in_file ./balloons-over-bagan.jpg --out_file ./balloons.png --targets 182 109 58 121 29 39 103 118 77 --steepness 0.25 --offset 40
Takes you from this...
to this:
I use a sigmoid function the looks at how dark a pixel is and, based on that, assigns it an alpha transparency. The sigmoid function is nice because it renders a smooth gradient against a transparent background, avoiding the awkward discontinuities that a simple threshold would create. The defaults I picked worked pretty well, but if you'd like to play with them this is the function you'll be adjusting:
--offset shifts the curve right and left, and --steepness controls the steepness of the transparency gradient. The larger this number, the closer your approximation to a strict threshold for transparency will be.