I found this GREAT preview text from the book The DC Comics Guide to Coloring and Lettering Comics. Referenced from books.google.com
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COMPUTER COLORING: THE DC WAY!
Of the many ways one can color using PHOTOSHOP, the following is the method preferred by DC COMICS.
Basically, you’ll be creating a duplicate black channel, coloring the page and then pasting that black channel back over top of the coloring. Here’s the step by step way to do it:
Before you start: You need to turn off the ‘Anti-aliased’ settings in the all of the PHOTOSHOP tools that allow you to do so. They are:
•ELIPTICAL MARQUEE
•LASSO
•MAGIC WAND
•PAINT BUCKET
You do this by simply double clicking on each of these tool icons and making sure that the little box next to ‘Anti aliased’ is NOT checked.
The reason you do this is, if you use any tool with ‘Anti-aliased’ selected, the linework of your artwork will turn slightly blurry during the ‘set up’ and/or ‘clean up' stages. Blurry linework makes it difficult to go back into your completed colored pages and make any sort of corrections.
STEP 1: SETTING UP YOUR FILES:
OK, so you’ve received your bitmap scans from DC (or you’ve scanned them yourself). Open up one of the pages in Photoshop. Since you’ll be working in CMYK mode (NOT RGB!!!), you’ve got to do the following: In the pulldown IMAGE menu at the top of your screen, go into MODE and switch the file from BITMAP to GREYSCALE (a little dialog box will pop up. Make sure the ‘size ratio’ is set at ‘1’, and then click ‘OK’). Next, go back into IMAGE and then MODE again, and this time change the GREYSCALE mode to CMYK.
Now, go over to your CHANNELS box and click on the BLACK channel. You’ll notice that only the BLACK channel stays ‘active’, and the others turn ‘inactive’. Hold down the little triangle in the upper righthand corner of the CHANNELS box, and select DUPLICATE CHANNEL. Another dialogue box will pop up, that shows your computer is naming this new channel “BLACK COPY”. Click OK. Now, click on the CMYK channel and all of the channels will become ‘active’ again, except for your new BLACK COPY channel.
Make sure the eyeball icon in front of each channel is on, including the one in front of your new BLACK COPY channel. This channel should stay inactive, but you’ll always want to be able to see it.
Select all (‘COMMAND’ ‘A’) and then fill the entire page with white (‘EDIT’, ‘FILL’). This will get rid of all of the color that’s sitting directly underneath your new black copy. You need to do this at this stage so it won’t interfere with the ‘clean-up’ step you’ll do later in this process. SAVE YOUR FILE.
If doing this has caused your ‘black copy’ to turn slightly gray, refer to the instruction box down below in ‘STEP 2: APPLYING COLOR’.
You have just set up your page, which is now prepped and ready to be colored. If you’ve done everything correctly so far, when you turn off the eyeball in front of the ‘Black Copy’ channel, the page should look completely white.
Let me take a moment to explain why you created a duplicate black channel. While coloring your page, it’s inevitable that you’ll mistakenly color over some of the original black linework. Since you’ve planned ahead and created a duplicate of that black linework, all you’ll need to do (once you’ve finished putting down all of your colors) is pop the duplicate back into the original black channel! (I’ll give you the exact instructions on how to do this later on in this document)
At this point, you need to check a setting. Do the following:
Double click on your new ‘Black Copy’ channel. A dialogue box will pop up that lets you choose ‘Masked Areas’, ‘Selected Areas’ or ‘Spot Color’. Make sure that ‘Selected Areas’ is the one that’s chosen.
Once you’ve selected this and hit ‘OK’, and then SAVED the file, you will never have to do this again (unless you buy a new computer or get a newer version of PHOTOSHOP). Now you’re ready to turn your CMYK channels back on and start coloring.
STEP 2: APPLYING COLOR:
One quick note about something you may encounter during the ‘coloring’ stage: If you’re using one of the newer versions of PHOTOSHOP (version 6, 7 or 8), you may notice something odd about the black copy that you’ve created. If you color over an area that has blackline in it, it will appear that some of the color will alter the blackline and make it not look like pure black anymore. This can be a bit frustrating and bothersome, but there’s a short step you can do to rectify this problem:
Click on your ‘black copy’ channel, which will select it and turn off all of the other channels (but all of the eyeballs should stay ‘on’).
In the pulldown IMAGE menu at the top of your screen, go into ‘ADJUSTMENTS’, then ‘LEVELS’. In the first ‘Input Levels’ box that appears, type in the number 25. You’ll notice that the little black triangle below has moved over to the right a bit. You’ll also notice that you’ve solved the problem and your copy of the Black Line has turned fully black again. Hit ‘OK’ and then click on the ‘CMYK’ channel, which will turn all of your channels back on and turn your ‘Black Copy’ channel back off. SAVE your file.
Because this instruction sheet focuses on the technical side of computer coloring, I won’t get into the many styles of the application and aesthetics of coloring.
If you’ve followed my instructions for ‘setting up your files’ and then applied digital color to the page, you’re ready for the final ‘clean up’ step.
STEP 3: CLEANING UP YOUR FILES:
There’s one important final set of steps you need to go through in order to prepare your final files. Part of this gets a bit technical, but once you do it a few times, you’ll get the hang of it.
Because of the way I had you set up your files, you have an extra, untouched black copy channel. Again, this was important to create because during the coloring process, you most likely colored over and on top of much of your ‘black channel’. Now, you need to paste the black copy channel back over the C, M, Y and K channels. Here’s how you do it:
•Go up to SELECT and pull down LOAD SELECTION. In the dialogue box that pops up, ‘Black copy’ should be selected under CHANNEL. Hit OK. You’ll see that all of your black linework is selected. Here’s where it gets a little confusing, but just follow these steps and I’ll explain why you did it this way later.
•Under SELECT, pull down MODIFY and then CONTRACT. Type in the number 2. This will make your blackline copy selection smaller all around by two pixels. Hit ‘OK’.
•Select the color C60 M40 Y40. Pull down EDIT then FILL. OPACITY should be 100%, MODE should be NORMAL. Hit ‘OK’.
NOTE* if you were to turn off the ‘Black Copy’ eyeball, you’d notice that everywhere that should be black is now grey. This grey is called your “undercolor”.
•Select your BLACK COPY again (SELECT/LOAD SELECTION/OK). Now, fill this selection with K100 (EDIT/FILL/MULTIPLY). Make sure you fill it at MULTIPLY this time, not at NORMAL. This will put a layer of flat black ink over your ‘undercolor’.
•Delete your extra BLACK COPY channel (by clicking on the BLACK COPY channel, going up to the little black triangle in the upper righthand corner of the channels box, and selecting DELETE CHANNEL).
SAVE!
If everything has gone well, you should now have five channels (CMYK, CYAN, MAGENTA, YELLOW and BLACK). Just to check, click off the eyeball for the BLACK channel, which will make that channel invisible. If everything has gone well, you should be able to see the grey ‘undercolor’ underneath all of the areas that will print as black. If you zoom way in to look at the gray undercolor, you’ll notice that it’s actually slightly smaller than the black linework. Also, if you’ve done everything correctly, your color should butt up right against your gray undercolor.
OK, so why did you have to create a grey undercolor??? Here’s why: if you had simply put down your 100% black linework over your CMY coloring job, the black areas would look weak, and not print as a true, rich black. By adding a bit of cyan, magenta and yellow ink under the 100%black, you end up with a deep, rich black. The other reason is, this process cleans up any stray color that you may have put down underneath the black areas during the coloring stage.
OK, so why did you have to CONTRACT the undercolor by two pixels? Here’s why: If your undercolor was exactly directly under every pixel of black ink, you obviously wouldn’t be able to see it (which is good). But if the black plate shifted even the tiniest bit while on press, you’d see some of that undercolor (which is bad). As good as today’s professional printers are, there’s just no way for the line-up of colors and black ink to be 100% perfect
STEP 4: COLORHOLDS :
When you’re all done coloring your files and cleaning them up, if you choose, this is the stage to go back in and color-hold some of your linework. Here’s how you do this:
Turn on only your ‘Black’ channel and click on any area of black with the ‘Magic Wand Tool’ (set at a ‘Tolerance’ of 2). All of your black linework will be selected. Click back on the ‘CMYK’ channel, which will turn all of the channels (including ‘Black’) back on.
Now, using the pencil tool, and any color other than black, you can change selected areas of the blackline to a color. This is great for colorizing the linework around flames or energy bolts. When you’re done, SAVE your file.
One last thing, make sure any extra channels or layers you may have created during the coloring process have all been deleted before you send your final files into DC. They’re of no use to us, and will only make your file size much bigger.
