Computer coloring using layers:
1. Scanning and Prepping
A. The process starts with a good scan. The typical comic book page is drawn on 11 × 17″ bristol board, on which a template has been printed. I scan pages at 400 pixels per inch (ppi). Since my inks usually have blue-line pencils underneath, I scan in full color, which means they can easily be filtered out. (I have a Photoshop action to automate this process, which I hope to make available soon.)
B. Cropping, although fairly simple in concept, can streamline the overall process if done consistently. I have a crop tool set to the desired dimensions, 4125 x 6262 pixels, with the "Perspective" option checked. Since this allows the corners to be dragged independently, I can match them precisely to the corners of the printed border. Aside from keeping all your page files consistent, it keeps everything perfectly aligned — this is especially helpful when matching up digital elements with analog artwork, i.e. panel borders, logos, or 3D models. You can read more about the cropping process here.
C. Although our original scan is 4125 x 6262 px, the final color output will eventually be 2/3 that. That's because inks are saved in a different file format, a bitmap TIFF, which reduces the colors in the image to just 2, black and white. (You can control the specifics of this transformation under Image > Adjustments >Threshold.) While this saves a ton of memory (a typical page is under 500 KB) it requires a higher resolution to avoid a pixelated look.
2. Flatting
A. Color Flat layer: First I create a second layer under the line art or inks layer. The inked page goes on the top layer, the mode set to "Multiply," which makes all the white pixels transparent. The "flats" layer goes below that. The key to easy selection is making sure the flats aren't anti-aliased, meaning that no 2 colors are blended at the edges.
To create flats on the second “Flats” layer, Using the lasso tool, trace the one white shapes from the “inked” layer and paint bucket colors into the areas.You can be random with the colors at this point because they will be changed in the color process. Try to make the edges of the selections meet each other with hard edges so the selection process later is easier to handle. Make any changes to these shapes using a hard pencil so there will be no blending.
The purpose of flatting the colors is to break up the the color image into shapes, rather than to produce a finalized color scheme. Flatting makes it easy to select and alter patches of color. At the end of the flatting process you will want an RGB file with at least 2 layers, more if there are "special effects," pictured below.
Elements that will "glow" can be isolated on a separate layer.
Brush vs. Pencil
In order to preserve those hard edges, I use the Pencil tool when editing the flats (as opposed to the Brush tool). If I use the Magic Wand to select pixels or the Bucket to fill them, the tolerance must be set to "0" to avoid blending colors.
3. Coloring
Color every page at full resolution, just in case I ever need a bigger version. It's also to avoid a mistake I sometimes see colorists make. If you downsize your inks in their native, 2-color format, the inks will look pixelated when printed. Also, if you downsize your flats before coloring, it may not preserve the hard edges you worked so hard to create. While there are a few ways to avoid those issues, saving reduction until the last step makes everything easier.
Put simply, it's trial and error. Starting with artwork that's been flatted, I use the Magic Wand (tolerance set to 0) to select each patch of color that I want to modify. I then use the Hue/Saturation/Brightness command (under Image > Adjustments, or Command-U) to modify those parameters individually. You can also use paintbrush and other tools, selecting areas and altering them to add tones and textures for color.
The "Colorize" option
Sometimes the results of the Hue dimension can be tough to predict. When that's the case, check the "Colorize" option — it resets the all the variables so that you can achieve any color in the gamut in a predictable way. One caveat, though: if multiple patches of different colors are selected, it will unify their Hue and Saturation, leaving only Brightness to differentiate them. (Sometimes that's what you want.)
There are, of course, many other principles to keep in mind. Having a familiarity with color will help immensely, but if often shocks me how simple the process is, especially remembering how much I used to struggle with color. (The digital aspect of color alteration is so easy, I use it to plan all my traditional work as well.)
Hopefully, seeing the process in action will help to show how decisions actually get made. The first step is pretty straightforward:
TIP: For selecting color in you image with selection tools, make sure the Tolerance is "0" and all options are unchecked.
When selecting color with the magic wand, I usually leave the Contiguous option unchecked, so that it will select anything in the entire piece that's the same color. I do the opposite with the Bucket (tolerance set to "0" as well) since I usually want to color just one patch at a time. I use the bucket primarily at the outset — it's quick and easy, and best for bold moves with clear goals.
A Quick Mask to show the foreground group.
But elements don't have to be the same color to be treated as a group. I use the Channels palette to save selections that include different patches of color. These are called Alpha Channels, and they are useful for backgrounds, characters, groups of figures — anything you would like treated as a single element. If you're not familiar with Channels, it's worth your time to learn (you can start here). Once an alpha channel is saved, you can Command-click on its icon (in the Channels palette) to automatically make the selection again.
RGB Channels and saved masks
Once the easy decisions have been made, I begin to think more about mood, atmosphere, and environment. If there's an art to it, this is where it's at — give 10 colorists the same piece, and this is most likely where they will begin to diverge.
While I'll occasionally go off-model for characters, I tend to wait until I have their official color schemes in place. That way, global changes in color will retain the same relationships between isolated areas. The same goes for skin tones.
Color Balance is best for subtle shifts.
I also use Color Balance (Command-B) for adjustments, typically for less dramatic changes — a bit more cyan, slightly less green. When I'm more concerned about overall mood or lighting, I'll create a Photo Filter adjustment layer that will give a color cast to the entire piece. Be sure to check the Preserve Luminosity option if you want to retain your brightest areas. I like keeping it on a separate layer because I can tweak it as I make progress. Once I'm satisfied, I combine it with the main coloring layer. You can also mask this and other adjustment layers using your saved selections in the Channels palette.
The Photo Filter is great for getting colors in the same "key."
I wanted to make special note of color modes. I work in RGB, Photoshop's native method for calculating color. Although print is almost always my ultimate goal, I don't convert to CMYK until the very end. I'll cover the details of the conversion process in the next post, but you can find my reasoning here. The next and final installment will cover rendering and special effects.
The CMYK channels of the final, flattened artwork.
Finally, my Digital Tool Shop is up and running — as of now, it has 3 products to help streamline comic production (with more to come). My blue-line conversion template is free to download.
D. Special Effects:
“Color Holds”
(Be sure to click on each image to get the full-scale effect.) First up, we have what's known as a "color hold." This is where the black areas of the art are replaced with another color. It's a great technique for pushing things back in space — it's essentially a form of aerial perspective — and also for elements that are glowing (fire and energy beams) or evanescent (ghosts and smoke).
On the "inks" layer, use the Magic Wand to select all the black pixels. If you've done everything right up to this point, there should be nothing but black and white pixels on that layer, making it a clean selection. Press Command-J to copy that to a new layer (also found under Layer > New > Layer via Copy). On the layers palette, click the Lock Transparent Pixels option — this means that the transparent areas on that layer will remain that way.
Lock Transparent Pixels
Using the Pencil tool (to keep things aliased), color every area that you want to be a different color. You are welcome to use as many colors as you want, but it's best to keep things simple, especially if you'll be making subsequent edits.
This can act as your sole layer for line art, but I like to keep things separate. I usually select all the black pixels from the Color Hold layer and delete them. I then select what's left on the layer (by Command-clicking the layer icon) and delete that area from the original Inks layer below. This is not a necessary step, but I like having the option. Since I color myself, I often end up erasing many of the Color Hold lines, and so wouldn't want the ink lines below to peek through. (However, if you're coloring someone else's work, they probably wouldn't appreciate you altering the art.)
Basic, two-tone coloring
The "flat color" school. It's not an official designation, but people often use the phrase to describe it. All it means is that I use little to no gradients or highlights. The closest I get to the modeling of form is what's known as "two-tone" rendering, which is probably most familiar from animation. It's an economical, but very effective way of creating the effect of light on objects.
Still using my pencil tool, but with a rougher brush preset, I map out the interaction of light and shadow. This keeps things easily selectable, so you can still make color adjustments later down the line. Occasionally I'll use a more textured pencil for "softer" transitions, but it's still just 2 colors — the blending is merely optical.
Make sure the Sample is set to Current Layer.
Most of the time, I'm choosing a darker shade to create a shadow, but if it's a lighter image, I'll "paint with light," instead. Choosing the actual colors is a manual process, but something that gets easier with practice. The first thing I do is option-click the color I want to adjust — this is the equivalent of using the Eyedropper tool, which samples the color you click so that you can paint with it. (An important note: it helps to select the Sample: Current Layer option, which will disregard the effects of any adjustments layers above it.)
Once the base color is acquired, it can be altered by clicking while holding Control+Option+Command. This brings up the Heads Up Display color picker — a new color has been chosen as soon as you release the click.
Fade is a quick and easy way to "Undo" on a sliding scale.
If, after painting with the new color, you find the change to be too drastic, you can split the difference using the Edit > Fade command (Command-Shift-F). The dialog box that appears acts like an opacity slider — you can choose precisely how strong you want the effect to be. Not limited to color, this process can be applied to almost any edit just performed. This is particularly useful on skin tones, where we are most sensitive to subtle changes.
Shadow colors should tend to be darker and less saturated. I almost always change the hue slightly, thus creating a warm/cool dynamic. This is the same way I play with color in my painted work, it's just a whole lot easier to do here.
Once I'm completely happy with the overall look of the piece, I copy the Flats layer and rename it Color (in the layers palette, option-drag the layer to copy it above). I then select each and every section that requires additional rendering, mostly the shadow areas. First, I'll use the Burn Tool to darken areas in deep shadow. This results in the subtlest of gradients, but still gives the overall effect of flat color.
Blending Edges
I then switch to the Brush Tool, armed with an airbrush preset. I copy the color from the lighter tone and "dust" the shadow tone wherever they meet. This maintains the hard edge between, but gives the illusion of bright light bleeding into the darkness. As with everything, the degree to which you do this is a personal preference.
GLOW layer
I save all the super-duper special effects for a separate layer called "Glow." I set the layer mode to Screen — this makes all colors below it brighter, even when using a darker color — and airbrush over anything that is a strong source of light. This takes a lifetime of practice to do with paint, and a nanosecond on the computer (which is why it's often overused). It may be cheap, but it's effective.
E. Adding Texture
The final step is not necessary, but I prefer the look. Computer coloring is perfect — too perfect. It can have a sterile aspect to it, and so I use a filter to add a faux finish. All this does is add texture and variation to the otherwise featureless tracts. It's a small gesture, but it gives your eyes something to lock onto — makes it more tangible. I use Filter > Texture > Grain, but you could even scan in real paper to achieve the same effect. I will often take textures like watercolor and other photographed or scanned in textures to add interest to the piece.
Make sure you SAVE on a regular basis.
RGB to CMYK
During this entire process, we've been working in RGB mode, Photoshop's native gamut (Proof Colors turned on). Since our goal is print, we need to convert the image: Image > Mode > CMYK Color. It will ask you if you want to merge the layers. You do. Next, downsize the image to 2750 x 4175 px (that's standard comic size at 400 ppi). Finally, Save As a TIFF file (Command-Shift-S) with no layers or alpha channels. Check LZW under Image Compression (a lossless method) and hit OK. Now we're really done.
Coloring Line art using Channels
We usually scan original art boards (11x17) as 300 dpi bitmaps. If the artwork is 8x10 or so we'll scan at 600 dpi.
Better to scan 600 dpi greyscale, adjust levels to nice clean lines and then convert to Bitmap and then to greyscale again.
Make a copy of your original scan and put it in safe place. Then re-size the lineart to 150 dpi (or 50% of the original dpi, whichever is higher). This saves memory.
Convert the greyscale, to RGB (this also saves memory rather than working in CMYK).
Turn on CMYK preview (so you can get a better sense of how some colors will print).
Select all.
Copy.
Make a new channel by double clicking on the little page icon on the channels palette.
Name this channel “lineart".
PASTE your lineart into this new channel.
FILL the RGB channels with white to eliminate the lineart from these channels.
You now have a the lineart in a separate channel from the colors so it won't get painted over. You can see it by turning on the little eyeball in the channels palette.)
Color the page, using ALL FLAT TONES. NO BLENDS! (YET.) Keep all the contiguous colors different from each other. (That is, don't make two things that touch the same color.) Use the lasso to select shapes and fill (use alt+delete keystroke) them with flats. Make sure you DON'T have any anti-aliasing turned on in either the lasso tools or the pen/brush tools.
This all-flat version of your page is used as a mask, to help you re-select these shapes once you've blended them. So Select all and Copy.
Make another new channel like you did for the lineart.
Name it “flats"
PASTE your entire page into the flats channel. It will come in greyscale (because each individual channel is a greyscale image).
Now you can go ahead and render your page in the RGB channels. You can always come back to the flats channel to re-select something with the magic wand set to 0 tolerance, no matter how blended the shape is.
While you are coloring, you don't need to worry about being careful under the blacks. Here's how to fix it automatically. Save your file, so you can revert if it messes up...
Load Selection (from the Selection menu), and check the "invert" button. Select the lineart channel from the list (it should already be selected if it is the next channel after RGB). This will make a marquee selection of all the lineart.
From Selection menu, pick Modify:Contract. Enter a value of 4 pixels. This will "choke" the lineart to prevent fine lines from underprinting.
Pick the color 70C, 50M, 50Y, 0K (a standard underprinting grey color for most papers).
Fill the selection with the grey. This will back up your blacks.
When you're sure you're done, and won't need to make any more changes to your colors, Save your file again.
Throw away your flats channel. You won't need it anymore.
Convert your file to CMYK (we use UCR separation mode in the Color Separation Preference).
Now you need to up-res the color to match the original lineart. Re-size the image to 300dpi
Open your original line art file. Select All, Copy. Close lineart file.
Make another new channel on your color file. No need to rename it because it is temporary.
PASTE the hi-res lineart into this channel. It should fit the color perfectly.
Activate ONLY the Black (K) Channel and Load Selection. Pick lineart, and Invert.
FILL this selection with 100%K. It will merge the Lineart with the K-tone in your image.
Throw away the temporary channel you made to hold the lineart.
Now you have a finished, 300dpi, CMYK color separated file ready to send out! In regards to file format, we save in PSD while we're working (so we can save layers) and then save as LZW compressed TIFFs for output to the printer. We also sometimes save as Max Resolution JPG to send files via modem. TIFFs are preferred, though. Some people don't like to LZW compress them because it takes a lot longer to open and save them. But they are way smaller than uncompressed.
