Here is a short tutorial on I scan in and prepare my traditional drawings for digital painting. Nothing too unique here as I learned this same process many years ago from a book on digitally coloring comics. The goal of this process is to eliminate the white of the paper and have the clean black lineart on its own layer as a selectable object. If you are just painting over your lineart you can just put your drawing on its own layer and set to multiply.
1. Cleaning up the Drawing
Before the drawing even touches the scanner first you should clean up your drawing as much as possible. Erase any smudges or stray lines. This is something that was drilled into the way back in years of drafting classes. Plus, by keeping your original drawings clean it not only saves you time on the back end digitally but also ensures you have a nice traditional drawing to sell. For me, I typically use my kneaded eraser and eraser shield for this part.
2. Scanning in the Drawing & Document Setup in Photo Program
Make sure your scanner glass is clean of any smudges or stray hairs & dust. If not you may find yourself having to digitally clean this up afterward, when a simple wipe with a microfiber cloth would have taken care of it. Set your scanners scan resolution to at least 300dpi for print though I usually go 600 dpi or more just in case since I may not know what size prints I want to make afterward. You can always down-rez if needed later on. If the image is too large for your scanner bed scan the drawing section by section and then piece together in your photo program. A couple of years ago I invested in an Epson Workforce 7720 that can scan a 12”x18” sheet of comic bristol and this saves me so much time now. Love it.
Once the image is scanned in open it up in your photo editing program. For many people, this will be Photoshop. I recently switched to Affinity Photo. If working for print set up your document in the CMYK color mode at usually 300 dpi.
I then begin with a levels adjustment layer punching up the white and black levels further cleaning up the lineart.
Now we will use the channels to separate the drawing from the white of the page. To decide which channel to use turn all off and turn one at a time gauging which channel looks the cleanest. In this case, I forgot to change my document settings to CMYK and left it in RGB, no biggie, as it doesn’t really come into play till we start painting so I’ll be sure to convert it to CMYK before then.
For this drawing, the Red channel was the cleanest channel with blue being the ‘dirtiest’. This could change if you did an underdrawing in a different color. You can see this in the channel comparison above especially if you look at the under-arm and neck areas.
4. Create A New Layer
Now with our clean channel identified to create a new layer. This will be the layer where will create our clean lineart using that channel.
5. Select the Cleanest Channel
Selecting a layer is generally done by right-clicking on the channel-layer, then clocking the option from the drop-down menu that appears. In Affinity, it is the ‘Add to Pixel Selection’ option as the screenshot shows.
6. Reverse Selection
When you select a channel layer it creates a selection of the white space in the image, but what we want is the exact opposite, the lineart. So to accomplish this reverse the selection. In Affinity go to the ‘Select’ Menu and then ‘Invert Pixel Selection’. It is in a similar spot in Photoshop in the ‘Selection’ menu. Now we have a selection of just the lines of the drawing. The screenshot below shows the selection with the original drawing layer named ‘Background’ in this file turned off. Almost there.
7. Fill the Selection
Now to create our working lineart. With the new layer, we created highlighted fill the selection with black for now. The color can always be changed later on. Tada! Now you have a layer of just your clean drawing.
8. One Last Drawing Preparation Step
The last step I take to prepare the lineart for painting is to alpha lock this layer. What this does it lock the transparency of the layer so that now if you were to accidentally paint on this layer it would only affect the lineart and not the empty space. Prevents me from accidentally messing up all the work I just did as I paint. In Procreate this can be accomplished by clicking on a layer then selecting ‘Alpha Lock’.
At this point, you can select this layer and easily colorize your lineart at any point in the process if you want to. Either by filling the layer or if you just want to colorize a particular area of the line you can paint in it.
I typically will go in now and further clean up my lineart erasing out little marks, cust/scratches, etc. You can also now digitally ink this linework if you want it even smoother or need to beef up your thick to thin flow in the linework.