After taking a quick look at this article: http://bit.ly/1juSUMb I decided to revisit the joy of dots and show this technique for creating lovely out-of-register four-colour process like those cool comic books of days gone by.
For this I’m using a cartoon of myself – this kind of technique works really well with flat colours, and you could use any source image, of course.
Select Black Lines
If you’re going for the comic-book look, you’ll need to select the black lines – I don’t usually want these half-toned, as I tend to work on them (blurring slightly, etc.) at the end stages. I used the Magic Wand with contiguous option deselected to get these quickly.
Convert to Multichannel
Now we’re going to convert to a multichannel image: Image > Mode > Multichannel which will split the image into CMY channels – our selection should still be active and we can then use that selection to create a new (black) channel.
Create a Black Channel
If you’re not already there, make the Channels panel visible (it’ll either be nested with the Layers panel, or you can go to Window > Channels); then go to the panel flyout at the top right of the panel and choose New Spot Channel – click through the ensuing dialog and your selection will be taken to a new channel for the black information.
Now target in turn, each of the Cyan, Magenta and Yellow channels, and apply the colour halftone filter (Filters > Pixelate > Color Halftone). You can either apply the filter as is (with the default screen angles) or you can play with the first field’s value (which will be the only one applied on a single channel) to get different results. Once done, select the Move Tool and using the arrow keys on your keyboard, nudge one, two, three or all of the channels a pixel or two so that they misalign.
Converting Back to CMYK
Just for fun, try doing that now; observe what happens, and then undo. We need to adopt a different approach here as Photoshop is just converting the first four channels it finds and as you’ve already seen, there’s quite a shift.
Adding Alpha Channels
Using the New Channel button at the bottom of the Channels Panel, add four alpha channels.
Invert and Shuffle
Select each of the Alpha Channels in turn, and invert them so that they show white – use the Cmd-I/Ctrl-I shortcut to make this a bit quicker. Once that’s out of the way, drag them to the top of the stack.
Now change the image back to CMYK – Image > Mode > CMYK.
You’ll notice that the channels just look like any other CMYK document, with a composite channel and the four component channels beneath. They won’t look too exciting in print though, so we need to get the information back into those blank channels.
Select the auto-renamed Cyan channel (made from your first alpha channel), then shift-click the cyan channel from the multichannel; go to the panel flyout and choose Merge Spot Channel – the two will be merged into the actual Cyan channel. repeat for the remaining three channels.
The Finished Result
You’re done – there are a number of ways to do this but I like it as I can control the misalignment in a few ways. You may want to blur your black channel a little bit either globally or with the blur tool, and you may also want to reintroduce a bit more saturation into the colours as well as converting to RGB if you’re going to use it on-screen.