TUTORIAL: Inking a sketch and simulating non-photo blue

I love drawing with my Pentel brush pen. It’s super handy in that I can draw with ink without having to worry about the mess of multiple brushes and water or knocking over an ink bottle or what have you. I am also a digital artist, which means that I am gripped with anxiety at the thought of not having my trusty Undo to fall back on. Traditional art is so permanent! I am thoroughly spoiled by technology.

To get around these pitfalls, I figured out my own technique for inking sketches using both digital and traditional methods. This way, stray ink strokes or accidental smudges don’t ruin my sketch and I always have the option to start over.


  • Pencil or pen for sketching

  • Ink for inking (I used a Pentel pocket brush pen)

  • Scanner/Printer

  • Photoshop

Start by drawing your sketch. This is just a quick one I did in Sharpie. It's based on a coyote skull I got in Alaska a while back. Rest in pieces, noble dog. 

Once the sketch is done, scan in grayscale so you don’t have to deal with discarding any color information when editing the brightness. On principle, always make sure to scan at 300 dpi or more so it can be printed later! Though this is just a sketch so you don’t really have to worry about that right now.

Open the sketch in Photoshop. Then you do some brightness adjusting. Sometimes a scan will still show some texture of the paper or a shadow, so turning up the white levels gets rid of some of the faint gray tones. You want the lines to be pretty distinct. Go to Image > Adjustment > Levels and the window will open. Grab the the tab on the far right of the histogram and drag it to the left a bit to adjust the intensity of the white tones. (Far right tab = white tones, far left tab = black tones, middle tab = gray tones.)

Here’s a cool thing: You know when you see traditional media artists sketch with a blue pencil? This is because, back when the method was more common, certain cameras or photocopiers wouldn’t pick up that shade of blue (“non-photo blue”) and so it would only capture whatever wasn't blue. We’re gonna simulate that process here.

Trust me, some of that is  probably  blue.

Trust me, some of that is probably blue.

First, go to your top menu, click Image > Mode and pick RGB. If you scanned in Grayscale you’ll need to switch it back to color now that we’re done adjusting the white. Then create a new layer and bucket-fill it with blue. I kind of just picked a shade that looked right but upon research I found that the “official” hex code for non-photo blue is #A4DDED. If you want, you can input that code next to the hash sign in the color picker window; just click on the color box in the lefthand toolbar to open it. 

Make sure that blue layer is above your sketch. Then change the Blend Mode of your blue layer to Screen (this is the dropdown menu beside the Opacity percentage in your Layers palette). Your sketch is now blue. Look at you go, Champ.

And it's ready to print out for inking! I actually took some sketch paper and fed it through my printer. Normal printer paper might soak through, especially if you’re using a brush and bottled ink.

Now you’ve got a sketch that you can ink without fear. Maybe you want to do several different styles of inking, or you’re afraid you’ll mess it up? Sure man, if you do, you can just print out another sketch. Maybe you’ve got a bad eraser and when you try to erase your pencil lines under your ink, it just smudges everywhere. Well now you don’t even have to erase; we’ll have Photoshop do the work!

Once you’re done inking, we can scan it again and open it in Photoshop. I do the same Levels adjustment until all that’s left is black ink and blue lines. I pick the Eraser tool and get rid of some stray marks I don’t like.

Time for the blue lines to do their disappearing act!

First we want to make sure the ink is pretty dark. Here’s another quick way to do that:
 If it’s a background layer, unlock it by double clicking the layer, and click OK when it prompts to rename it. Right click it, and duplicate the layer. Then change the Blend Mode of the copy layer to Multiply. This mode kind of simulates the idea of having your art printed on a sheet of transparency paper, so whatever art is on that layer will be see-through and may darken whatever is under it (which is what we want to happen).

Flatten the two layers so you have just one again (the button in the top right corner of the layers palette opens a menu with the option to Flatten Image).

Convert the image to CMYK (Image > Mode > CMYK). When a window pops up prompting you about color profiles, just click OK. Go down to your layers palette and choose the Channels tab.

Right click the yellow, magenta, and cyan channels and delete them.

You’ll see that the blue has been removed from your drawing. You can return to the layers tab and tweak the white and black levels again if you want, but other than that: Ta-da! You have a lovely, pristine ink drawing and you didn't have to destroy your original sketch to do it. 

Since the picture is now missing some channels, you might have trouble saving it as an image file. Just change the Mode to Grayscale and the options to save as a .jpg or .png, etc., will become available.

I hope this was helpful! What do you think? Leave a comment if you have any questions, and share this post if you think someone you know might learn something from it. Thanks for reading!

The art featured in this tutorial is from the Live Fast Die Howling design that is now available as a free wallpaper pack. If you'd like to download it, subscribe to the newsletter here!