Step 2: cleaning the scan
As you can see, we're still prepping the original image and aren't yet in coloring territory. That's because there are lots of steps that should be followed in order to ensure the finished product looks as amazing as you intended it to. For example, cleaning is vital because certain parts of the image can drastically change how colors look: screentones will make your colors look darker, artifacts will stand out even more when the image is colored etc.
These being said, there are two types of cleaning you can face when working with scans:
2.1 Simple cleaning
2.2 Advanced cleaning
2.1 Simple cleaning
If you come across an image that needs only simple cleaning - boy, are you lucky! This only involves fixing the lineart and the lighting and possibly using some filters to sharpen or blur it, if it happens to be too blurry or too sharp. Nowadays, scanlators usually have high standards when releasing manga, so most of the scans are properly cleaned and do not need filter cleaning; at most, you can modify the contrast on the lineart if you feel it's not high enough.
Levels and Curves are very good for fleshing out outlines and generally dealing with contrast. I recommend Levels because you have control over the shadows, highlights and midtones, while Curves are more random (but can also yield surprisingly good results). Count on Levels for certainty and on Curves if you're feeling lucky or want something different. (from here)
As for filters, I'm talking mainly about Sharpen here. However, pure Sharpen is usually too strong for images and you'll end up with white pixels around the outlines. This is where dear old Smart Sharpen comes in; Smart Sharpen deserves its praise because you can select the amount of sharpening you want to apply to the image, so now you don't have to worry about it looking too rough.
Let's not forget about the blurs. Box Blur and Gaussian Blur are good for softening images: 1px radius, 60-80% layer opacity. It's kind of a dark glow that makes outlines look less pointy and will sometimes even dim color leakages. However, don't use this all the time and never to hide mistakes! (from here)
Related tutorial: Basic scan cleaning
2.2 Advanced cleaning
Everyone knows that advanced scan cleaning is where it's at; this is your opportunity to flex your scan cleaning muscles and show everyone how awesome you are at working that fickle Clone Stamp Tool. So what's it all about?
It's about using a combination of filters and manual labor to metaphorically beat that image into submission. It's about reconstructing missing parts and playing with filters and blending modes in order to make that thing shine - because advanced cleaning doesn't disregard basic cleaning, but builds on it.
To reconstruct an image, you need to be at least at an intermediate level in graphics editing and have a good understanding of proportions and movement (joints, movement trails etc.). Sometimes you may even find yourself needing to recreate entire body parts and not just connecting a few stray lines. For me, there are three ways to approach this:
1. Look for similar images: if you need to reconstruct a hand, look for images of hands. Careful, make sure they're in a logical position (not bending in a way that makes them look deformed) and that they fit the style of the image!
2. Make a sketch: here's an old sketch of mine which I used on this vector (original scan is here). How detailed the sketch is depends entirely on you; it is there only to act as a guide so you can reconstruct the image better.
3. Use parts of the same image: for example, if a character is missing a shoulder, you can mirror the existing shoulder (rotate it horizontally and place it so that it looks normal). This doesn't always work, though, and can result in a very unpleasant "mirror" effect because of the symmetry; no human being is symmetrical, so try to vary some lines (place the shoulder a bit lower, make it more/less curvy etc.). This doesn't really apply to object that are symmetrical to begin with, but variation is encouraged nonetheless.
You also have two technical methods or reconstructing your scan:
- via the Brush Tool: also called "painting", means just dragging the brush along the lines you wish to create;
- via the Pen Tool: depending on your Pen Tool settings, you either stroke or vector.
The Pen Tool is useful for scans that are so covered up by text/other images etc. that you can't just use the Stamp Tool on them - there are no areas to replicate or they are too small. Likewise, if you have an image with lots of curves (hair, clothes etc.), it's better to just use Stroke on them in order to avoid blocky-looking curves.
Tip: be wary of gradients and screentones, as they tend to be somewhat-to-very difficult to clone. To make sure the image looks alright, zoom out periodically enough to be able to see the entire image, and check for anything that looks out of place.
"Stroke" also makes use of the Brush Tool but ensures better control over curves and straight lines. "Vector" makes use of shape layers, which means that part of your image will not become pixelated/grainy when enlarged. However, I find vector layers pretty much useless when reconstructing scans (unless you plan on changing the colors often), since the rest of the image is rasterized and will become pixelated when enlarged; therefore, I use Stroke all the time since it's also less time consuming and more practical in the long run.
Here are a few examples of reconstructing missing parts:
Related tutorial: Advanced scan cleaning
And now for the long-awaited step 3, coloring the scan!