Separating lineart from background – Photoshop

To color lineart in Photoshop, separating lineart from the background is essential.

When I first started I used Adobe Photoshop a lot. Truth be told, I don’t use it that much anymore because most of my clients prefer illustrations to be in vector. Adobe Photoshop has some serious advantages to Adobe Illustrator though. Simply put it’s use of color is more paint like compared to Illustrator and if you want to blend colors and emulate a more paint like feel Photoshop is the way to go. But that’s a blog for another day :).

My first real problem when starting with Photoshop was not knowing how to scan my lineart and easily color the illustration. I found there is a multitude of ways how to approach this. Here I’ll show you 2 or 3 ways how to do it. All of these seperate the lineart from the background and allow you to color in a seperate layer from the lineart.

1st approach – using non-photo blue pencils

Non-photo blue pencils are exactly what the name says they are. They are a special shade of blue that does not show when scanned or copied (but the scanner or copier must be set properly). This allows you to sketch your art and draw your lineart over it without having to erase the sketch. This was used a lot before programs like Photoshop became readily available. The trick is to set the scanners media to lineart and the DPI to 300. I usually set my preview DPI to 75 because my scanner takes forever to finish scanning. The preview isn’t really all that important when scanning things like this anyway.

Open the scanned file in Photoshop and navigate to window/channels. Ctrl (cmd on mac) click on the main (RGB) channel. This selects all the white areas in your image. Navigate to select/inverse. Now that we have all our lines selected create a new layer and use the fill tool to fill in the selection with a black color.

2nd approach – using any blue pencil

With the advent of Adobe Photoshop it became possible to use any blue pencil and erase it with a few simple clicks. Basically you use your scanner to scan in the lineart with your sketch still underneath. You open the file in Photoshop and navigate to image/adjustment/levels and play around with the levels a but to brighten up the white and darken up the lineart.

Moderation is the key here and I can’t really tell you how to set your levels because it depends on the scanned image. Experiment a bit :). Under channels select the blue channel. All other channels will automatically turn of and you’ll see the blue sketch disappeared. The process is the same as with the 1st method but instead of selecting the RGB channel select the blue channel. You can also do this with a red or green pencil but you have to select the coresponding channel when selecting the lineart.

3rd approach – another way to separate lineart from background.

This is just another way how to separate the lineart from the background (assuming you don’t have a sketch under the lineart anymore). Open your lineart file and ctrl (cmd on mac) click on the layers thumbnail image. Then navigate to edit/cut. Now press the Q button on your keyboard (or find the button in the toll bar). With that you have entered quick mask mode. Navigate to edit/paste and you should see your lineart in the image but in red. Now push Q again (or the button in the tool bar), navigate to select/inverse and color in the selection with the fill tool (black or whatever color you prefer). I find this method usually gives you a less transparent lineart then the first two methods.

4th approach – using the blending mode option

This is the fast way to do this. Open your scanned image (assuming you don’t have a sketch under the lineart anymore) select the layer the lineart is in. In the layer panel set the blending mode to multiply. The image won’t change much but if you create a layer underneath the one with the lineart and color in to it you’ll notice that even though the white background wasn’t erased anything you put in the layer underneath it will actually appear above the background but under the background.


Any of these options will make coloring of the art easier. More on that next week ;).

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