Coloring Your Lines

Sorry for bothering, but do you know how to get Krita to let you paint color inside lines? For example, I drew line art and now want to color it entirely purple, how do I make it so the purple doesn't go outside the line art even if my cursor does?

Do you mean you want to color your actual lines, or if you want to fill your drawing with color (like a coloring book)?

Coloring Your Lines

For coloring your actual lines, you’ll want to lock the alpha of your layer. Sounds complicated. But its actually a one button fix. It makes it so that you can only draw on parts of the layer that have already been drawn on. 

Now you should be able to color your lines any color you want to. You can fill them, use a brush, gradient, etc. 

Coloring Inside Your Lines (Fill Tool)

If you have CLEAN line art. You can actually use the Fill Tool.

(An example of clean lineart. No breaks. Clearly defined, solid lines.)

Make a layer under your lines for your color. 

You can find your fill tool on your Toolbox Docker. (Any missing dockers can be found under Settings>Dockers)

In your Tool Options, there is a setting that can make filling your line art very quick. Its called Grow Selection.

And if you set the number up till about 2 pixels, it should expand your fill tool so that it fills the line art nicely. Here’s an example of what the fill tool will do with and without the use of Grow Selection.

Now you can use the Fill Tool to click inside spaces and fill them with color. You can do each color on its own layer, if you wish. 

You may have to go in with a brush and clean up small areas that the fill tool may not have reached, but this is a nice way to quickly fill clean line art. 

You can also turn on alpha lock for color layers as well, and color inside them easily. 

Coloring Inside Your Lines (G’MIC Filter)

If you’re like me, and you use sketchy, pencily lines, or you have a lot of breaks in your line art, the fill tool probably wont work so well. But there is a filter you can use to help. 

First, create a layer under your lines like you did the last time. Now, fill in spots of the image with the color you’d like them to be. Make sure to set a color outside the lines, otherwise the filter will fill it with one of your other colors and the filter won’t work correctly. The color I used is lime green. 

Now. SAVE your file. 

Now, with your color layer selected, go to Filters>G’MIC. 

Now choose “Active and Above” for Input. This tells G’MIC to consider your color layer and your lines layer, which is above it. 

Next, in the filters list, under Black & White, choose Colorize (Comics). 

(Don’t worry too much about what the Preview looks like, here. Mine always look chaotic and messed up. The actual filter looks much better)

Now, to the right. I usually have it set so that it creates a layer for each color.

After that, hit OK to run the filter. 

Your result should look something like this. 

From here, you can delete your background color layer and do any necessary clean up.  If you want all of your colors on one layer, you can select them all by clicking on them while holding Shift, and merge them with Ctrl+E. 

Now, this extra step is optional, but since my lines can sometimes be thin and see through, I tend to do this. 

If you turn off your Line Art Layer (Its name is probably different, but it will be the layer above all the colors. You’ll see that the edges of the color are pretty sharp and not anti-aliased. 

It can look kind of gross behind thin and seethrough lines. I use the Blur filter to fix it. 

I set it to a radius of just 1 pixel. It usually does the trick. 

Hit OK and run the filter, and your results should be a lot nicer behind your lines.

For more complicated line art, sometimes I use the filter fill the entire inside with just one color, alpha lock the layer, and color it by hand with a brush tool. 

I hope this tutorial was helpful!