I wanted a way to quickly color loose lineart without needing to close any lines, so I juryrigged a setup with G'MIC's existing automatic colorize method (which you may have used in GIMP or Krita). Hopefully, it'll help someone else out!
- Be sure to install G'MIC for the command line (NOT the plug-in!) from the official site here, or the script won't work.
- The script itself can be found on my GitHub.
How to Use:
Save your lineart as a transparent .png sequence to its own folder, in 0000.png etc. format. Here's a gif of my lineart as an example.
Go into Object mode and use a bunch of small cubes to mark regions of color (not Grease Pencil--OpenGL has weird issues with antialiasing that mess colorize up), being sure to work in the Blender Render engine and setting the material to "Shadeless." Move the cubes accordingly with the lineart in each frame. Don't forget to add a color for the background, or it won't work! Here, I chose blue.
Then, export this as a sequence to its own folder--again, transparent.
Now, go into the script and change the appropriate variables to reflect the folders you're using. Make sure both lineart and color have the same dimensions and duration. Run the script, and voila! Instant coloring!
When I lay the lineart over, however, I can see it isn't perfect.
So, I bring the sequence back into Blender as a background image (toward the bottom of the properties panel).
Now, I turn on fill in grease pencil and edit the areas accordingly.
Composite it all together while replacing the background color with transparency, and that's it! Feel free to integrate it with other things, and let me know if you have any suggestions :)