Cel Shading, Exterminatus Now style

People have asked a couple of times how I colour and shade the comic. So I put together this little bit of a tutorial. I used Adobe Photoshop 7, but there's nothing here that less recent versions won't support. You will of course need some prior working knowledge of Photoshop. I go over and explain some of the more esoteric functions, but this isn't an absolute beginner tutorial, and you'll need to know your way around the 'Shop already.

Preparing the line art

Drawings should be inked, and the pencil marks erased before you scan. Scanner software varies, so you'll have to figure out the specifics on your own. You should scan your inked line art as a black and white bitmap. This may make it look a bit jaggy around the edges (especially if your inking's as crappy as mine), but if you scan it big enough (about 300 dpi), then you can size it down later and Photoshop will smooth it out. Import into Photoshop, if you didn't directly. If you need to tidy up your lines, do it now while still in bitmap mode.

If we're gonna have colour, we need to be in RGB mode.
Image>Mode>RGB Color
You may need to convert the bitmap to greyscale first before RGB becomes available.

You need to get the lineart on it's own layer, minus the white areas, so you can colour on a layer underneath. You could set the line art layer to 'Multiply' blending mode, thus making the white areas transparent, but this can cause problems later on. I'll go through the best way to do it. This method works for smooth, anti-aliased, greyscale line art too.

Find the 'Channels' tab. Usually next to Layers. If you can't find it, select Window>Channels. It should look something like the image to the right.

Make a copy of the Blue channel by dragging it onto the new layer button, highlighted in the image at left.

Notice the other channels have been deactivated, and the new one, 'Blue copy,' is the only one active. Click on 'RGB' to turn the RGB channels back on, then go back to the Layers tab.

From the pull-down where it says 'Channel', you should be able to select the 'Blue copy' channel you made earlier. Make sure and hit the 'Invert' checkbox before OKing. Now you'll have a marching ants selection of your line art.

All that's left is to fill it with black and deselect, and you have your transparent floating line art ready to colour.

Colouring and Shading

Create a new layer called 'Colour' (or 'Color' if you must) underneath the line art layer. For EN's shading, I put all my colour on the same layer. For the CG soft shading as seen at Perfectly Chaotic, there's a different method. Some other time perhaps.

Fill all the areas with the paint bucket tool, with the options set something like this:

The anti-aliasing and tolerance just ensures you get a small overlap of colour under the outlines. Not really neccessary with these pixel-crisp B&W lines, but if you're ever colouring softer lines, it can be handy. 'Contiguous' means it'll stay within the lines - if you turn it off, the paint bucket will fill all areas. And 'All Layers' tells the paintbucket to actually recognise your lineart (which is on a different layer) and only fill inside those areas.

It's probably a good idea to make the 'Background' layer a different colour, to make colouring white areas easier. Once it's done, we move onto the shading. Create a new layer between the colour and the line art, and set its opacity to 30%.

Group the shading layer to colour layer, by hitting Ctrl+G. Grouping them means anything drawn on the shading layer will only cover the contents of the colour layer - It means you can't go outside the edges, so you can be as sloppy as you like in that respect. Next, take a black paintbrush and begin shading. I tend to use a slightly soft brush for the comic, but you can use a sharper one for a more authentic cel style.

A small note, but dark colours might need a darker level of shading than 30%. The trenchcoats, Lothar's fur, all these usually get a 50% shade. To do this, I'll turn off the Shading layer, and magic wand select the dark grey areas. Then, with the Shading layer active, hit Ctrl+Shift+J. This cuts the contents of the selection onto a new, separate layer. Then just change the opacity.

From here on out, it's basically a matter of practice, learning how to make the cel shading work for you. First choose a light source for the image. I always light from the top left, for no particular reason other than habit. As a starting point, if your lighting is top left, then shade bottom right. But to shade effectively in this style, you need to start thinking about the 3-dimensional shape of the object. Rogue's hair, for example, sticks out and so casts a shadow on his face. His chin will cast a shadow on his chest too (though I haven't shaded that yet). Think about where the light will fall, and what areas will be cast in shadow. I don't pretend to be any expert on this subject, though. I cel shaded the first EN comic on a whim, having never attempted it before. I'm still learning it myself, and the shading in EN is pretty basic anyway.

So that's pretty much how it's done. Or at least, how I do it. Now you know.

    - Virus