"LayerPaint" is a paint software that support multiple layers. Interface of LayerPaint is really simple, but it also contains most of the features necessary for mobile-painting (image editing).
You can paint with switching Brush, Eraser, Line Draw, Fill Rectangle, Select Rectangle Region, Move, Bucket Tool, Gradation, Spoit, and Hand Too…
Extracting Lines Tool. Export as Transparen PNG Image.
1. Touch Screen and Open Image
2. Correct Levels.
3. Share (send to other apps) or Save
If some trouble happens, choose lower resolution (1024px or 640px).