5. 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 so rough.
Here's a side-by-side comparison of Sharpen and Smart Sharpen:
Let's not forget about the blurs. Box and Gaussian are good for softening images that look too sharp: 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!
6. The Green Screen
Yup, the movie term. However, I don't use it to remove stuff from the picture, but to see mistakes. This is nothing spectacular, it's just a layer placed under everything else so you can see what you're doing wrong. It is especially useful when working with light colors.
You see, when making icons, I end up coloring manga scans 90% of the time; being the impatient monkey person I am, I just drag the brush across the area I want to color without bothering to fit within the lines. Afterward, though, it's time for cleaning up. This is where the Green Screen comes in, since it's very helpful for spotting and correcting color leakage.
Contrary to the name I use, the Green Screen isn't always green; it depends on the colors you're using in your icon. If they're shades of green, you obviously won't use a green for the screen and instead stick to its counterpart, red. Here are some recommended hues for your eye-popping pleasure: ff008a (pink), fff000 (yellow), 00fff0 (cyan), ff0000 (red), 00ffc6 (turquoise), d2ff00 (lime), a200ff (purple).
Stare at them long enough and they'll start moving.
7. Blending Modes (BMs)
They are your friends. When making manga icons, the BMs I use most of the time are Multiply, Screen, Color/Linear Dodge and Color/Linear Burn. Let's see what each of them does:
Multiply is a BM I use almost exclusively for the base image, which is the one I want to color. Its main advantage is the fact that it "keeps" dark colors while getting rid of the lighter ones (or blending them very well). This is especially useful since manga scans are black & white and using this will leave you with only the outline, which you'll then fill with color. Place the base image layer on Multiply above all other layers.
Color Burn and Linear Burn I use solely for outlines, especially LB since I find that it looks good with all colors (CB doesn't work well with light colors as the outline tends to disappear).
Tip: some base manga images look great when set to Color/Linear Dodge instead of Multiply! (see image below)
Variations on the same image.
Screen is useful for highlights and other "glowy" effects; it is the opposite of Multiply in that it gets rid of darker colors and keeps the lighter ones. I don't use it very often since I prefer sharpness and don't work with glows too much.
Color Dodge and Linear Dodge are, like Screen, useful for highlights. Color Dodge blends the colors more, while Linear Dodge "burns" them; you'll end up with highly contrasting colors so I'd recommend using these BMs for hair highlights, if the base hair color is dark and less visible (black or dark brown). Personally, I like using these two BMs rather than Screen, since the latter makes the colors look lifeless most of the time.
Darken is useful for an extra touch of color, since it replaces the lighter hues of the image/coloring with the color of the Darken layer. This effect is best used when the image has a moderate amount of white (since that's the color that will be replaced first), since it tends to obscure details on images with too much white and isn't even noticeable on those with little white.
Lighten is a BM I don't use too often. Its effects are like those of Darken, but only darker hues will be replaced.
Tip: set the base image layer to Color Burn and an 80% opacity, duplicate it and set the copy to Linear Burn.
Lighten, Darken and Screen.
And finally...
