Painting a Picture Over Line Drawing

ACTUALLY TURNING A PICTURE INTO A LINE DRAWING

Which is what we have to do first to get there. So I've been doing research and trying to find a good tutorial on line drawing... turning a color photo or graphic into a line drawing (like a coloring book). I know there are apps for that and AI could probably do it all for me but... I like to learn new things and I don't know about you but I can spot AI a mile away on most graphics.

But really, I just like to do it myself so I know how it's done. I started with this colorful drawing and first duplicate the layer. 

                                                  

Working on the bottom layer and turning off the top layer, I used the menu on GIMP 'Colors | Desaturate | Desaturate' and with the setting 'value HSV' to get it to this nice b & w picture. You might like the other settings better so play around with them if you have time. But this is how I did it.

Then I go to a step most everyone else has skipped and I had to discover it on my own. It didn't seem to do much for this one but it works magic on other pictures I've used it on. It makes everything black and white and gets rid of all the mid tones. I go to 'Colors | Posterize' with a setting of 5 but you will adjust it to look right for your picture since all pictures are saved a little different. There is no one magic setting that makes them all the same. It helps to have an artist's eye.

Then I go to 'Filters | Edge detect | Edge' and I used 'amount 2' in the algorithm and it looks like this.

Now it looks like negative so we need to reverse it to remove the rest of the gray areas. Go to 'Colors | Linear Invert' and it looks like this, all black and white. You could play around with it some and see if you can get it better.

If you need to, you can use the 'dodge/burn' tool to burn in the edges that are a little too light. Or you can draw them in with the pencil. Next step is to turn on the top layer and grab the eraser tool. Set your brush on the settings below with the angle at about 50.

Now select the top layer and 'Layer | Transparency | Add Alpha Channel' to it. Now you can start to erase parts of the top graphic to show the bottom b & w graphic underneath. Now it's starting to look cool.

So I wanted to put a brush on mine to look like I was painting the color onto a b & w drawing. I actually scanned in one of my paintbrushes for this and colored the edge with whatever color I wanted to touch. And it looks like this.

I also put a drop shadow on the brush for depth. You can probably play around with all the settings and get something that looks a little better. I wanted a simple line drawing like a coloring book but it has a lot of detail for that. I still think it's a cool look!