Channel Separation Guide
I wanted to make a quick how-to on a technique that I use any time I make digital work. This process is probably familiar to anyone who works digitally on the reg, but for those who may not, it’s a very easy way to take analog artwork and make it easily editable in Photoshop. To put it simply, you’re going to be lifting your artwork off of the paper.
The basic term for this process is channel separation. The best part about it is that there’s not really one specific use, instead it’s a rather open-ended technique that can be applied in a huge range of ways. Because it’s so open-ended, I’m going to keep it simple by sticking to just the process instead of the myriad applications. All you need to begin is a high-res scan of your artwork with even lighting, and Photoshop.
I’m going to be using an ink drawing of the letter D from my 2017 Alphabet series.
Step 1–Prep work
Open up your scanned artwork in Photoshop, and save it as a copy of the original. This is important because we’re going to start by converting the image to gray scale, thus losing any color. Change the color mode to to Grayscale and discard the color information. Now’s a good time to assess your image. we’re going to be selecting any pixel that is not 100% white. If the paper is exceptionally dirty or off-white in color, adjust the levels of the image to achieve a clean background. I typically don’t get too wrapped up this step. All of these things can create little serendipities down the line.
Next you want to navigate to the Channels tab, typically located next to the Layers panel. You should see one channel called ”Gray”. Select this channel by holding down the Command key and clicking on the channel name. You should now see every gray pixel selected like this:
Navigate back to the Layers panel and create a new layer above the background. Make your fill color black, then invert the selection (command + shift + i), choose the paint bucket tool (g) and click anywhere on the artwork, then deselect (command + d) If you hide the background layer, you should see a translucent ghost of the artwork hovering over the checkerboard background of the artboard.
An important thing to keep in mind is that your separated artwork will always appear lighter than the non-separated. Keep this in mind when you’re adjusting the levels in step 1. A darker, more solid black then will mean a more opaque black after separation.
Step 3–Fun with color
Convert your document back to RGB, making sure you choose NOT to flatten the layers when prompted.
As I said before, there’s a ton of different ways to implement this trick, and I usually use a combination of a few of them at once. Give each one a try, remembering that messing up can lead to beautiful results, so don’t be afraid to try combining them.
With the background layer hidden, click on the separated artwork layer and invert it (command + i). It should appear white like this:
Now in the FX panel, add a color overlay. This is a good way to quickly add color to the artwork and be able to easily change it in the future. You can also experiment with adding a gradient or stroke at this stage, the results could be interesting!
You can also select all the pixels in the separated layer by command + clicking on the layer’s thumbnail, then use the paint bucket to add color.
Next, create a new layer on top of the separated artwork. Working in the new layer, command + click again on the separated artwork layer thumbnail to select all the white pixels. Now you can use the brush to lay down color in a new layer with the footprint of the separated artwork. Hide the separated layer to see just the path of the brush.
The last thing I’ll show you how to do is probably the most versatile. It’s a way to imply transparency without adjusting a layer’s blend mode, which can be a huge time saver if used properly.
So I’ve made another blue squiggle over top of the red D, but this time I didn’t have any pixels from the D selected.
Now, command + click on the thumbnail of the separated art layer (while working in the blue squiggle layer), and choose another color, then click a few parts of the blue squiggle to fill with the paint bucket. Voila!
This process definitely takes some practice, and the more you do, the more second nature it becomes. If you make artwork on paper and are looking for a way to digitize it, this is invaluable as way to do that. I hope this tutorial gets some wheels turning in your heads. If you make something during this tutorial, or after and want to share it, please don’t hesitate to email it to me! Thanks for following along.