In this tutorial we will learn how to use Adobe Photoshop to render line art like the pros in the comics. The following procedure is not the only way its done, but it is one of the methods used by professionals. This tutorial utilizes the Channels Palette, rather than the layers palette. This method is more friendly on your file size and memory usage. It also teaches you some fundamentals about channels in Adobe Photoshop. This tutorial is part two of a two part series, you will have needed to prepared your art work using the techniques in Part One.
I like to lay down a basic background color to establish a tone for my color scheme. You don't have to do this but I find it helpful. For now make the foreground color a darker blue and in the RGB Channel (select that channel) and press alt+backspace to fill the entire area. You will notice your line art remains untouched.
At this stage your channels should look something like mine shown here.
We need to create the 'Flats'. These will help divide our different color areas. It's important to do this part with care - even though it seems like the easiest step, it's important. To begin selecting color areas choose your selection tool, I prefer the Polygonal Lasso Tool, but some people may use the pen tool or even the normal lasso tool. Avoid using the magic wand. With the Lasso tool selected you want to switch the 'anti-aliasing' option off in the Lasso tool options. This can be found in different spots in different versions. This screen shot from the horizontal tool options bar in Photoshop 7. Make sure 'feather' is set to zero as well. Hover over the Images to see what they refer to. TIP: remember to save often and if you want, save incrementally as I do - adding a number to the end of the file name to show its progression.
Selecting along the middle of the line art is ideal (John has made his art work very easy to work with as you can see he has nice thick lines).
We are still working in the RGB channel. Once you have an area selected drop in a base color for that part using the Paint Bucket Tool (G) with a color of your choice. I like to go with darker colors as the flat colors tend to end up being my shadow areas color. Continue selecting and filling areas, keep the fills tight you don't what any color of one section showing anywhere in another. TIP: get to know your shortcuts in Adobe Photoshop. Shortcuts can be real time savers. Alt + Backspace will do the same as the paint bucket tool by filling a selected area with the foreground color.
At this point your channels should look something like mine shown here
We need to create another alpha channel like we did for the line art. The difference here is we are going to store our flats in case we need them later for selections. Okay this part might seem tricky but its quite straight forward. Select one of the channels (either R,G, or B not RGB) make a copy of that 'channel'. To do this press ctrl+a, then ctrl+c. This step selects the contents of the channel then copies it into memory. Now by clicking on the new channel icon at the bottom of the palette, or by using the fly out menu arrow on the top right select 'New channel'. With that new channel selected press ctrl+v. After all that, your channels should look like mine below. Name your backup channel backup or flats, etc.
When we created the new channel the visibility by default is off on all the other channels. Click on the RGB channel again and then click the visibility icon beside the Line Art channel to get back into business. Your line art and 'colored' flat colors should now be visible again.
This step is optional of course. As is usually the case I see changes that need to be made to the colors I chose for the flats. In this case I want the skin tones a little darker. Using the magic wand (w) I select the skin areas and apply a Hue adjustment (ctrl+h) and slide the lightness slider to the left. Feel free to experiment with the saturation and hue sliders at this point if you want. In this case I decreased the lightness a tad.
Figuring out your light source (direction of light) and how it effect the shapes is an important step in the process. I try to read the line art for obvious tell tale signs of where the light is strongest or what direction its coming from. Some things you may wish to look for in the line art is the line weight...a good inker will state an area further away from the light with a heavier line, than one that is closer. Remember as well, that light temperature and color can affect the highlight color as well. One thing you can do to help with rendering is take an object and place it on a flat surface then grab a flash light or other strong light source. Move in, out and around it seeing how it reacts and the cast shadows it makes, etc.
In the example provided I have begun by selecting the arms only, again using the magic wand. If you get other areas selected in this process you can correct with the Lasso tool (L). While holding the alt key - remove sections that are highlighted that you don't want. We are still working on the RGB channel. That's right, we are going to render this guy all on one layer (that's why we have undos and the history palette, and the backed up flats). No safety net of layers! Lets keep the file size manageable.
I used the Radial Gradient Tool, and selected the 'foreground to transparent' option as shown. Layer mode is set to Normal. Some people use screen or even dodge modes. I am not ready to do that at this stage so I just picked a hue that is higher on the HSB dialogue with a sample from the Eyedropper (I). Selecting the base color of the arm's skin tone then bring in up the HSB dialogue by clicking on the foreground color in the Tools palette. You can see the slight increase in volume by the subtle gradation of tones when I stroked the gradient across the selection. I did this going from the point closes to the light sources to furthest. This might take some practice so don't get frustrated, just keep trying. You can also do this with a brush as well.
Keep making selections and applying the gradient to areas you want highlighted. Keep in mind your trying to represent 3 dimensions-so look for areas that will have cast shadow and don't select those areas. This will help define your shadows more. In the figure below I have continued with he uniform and glove. TIP: For softer edges to your selections try using Photoshop's 'feather' feature... Ctrl+Alt+D and choose 3-5 pixels or whatever you feel is good.
We now have our lighting direction figured out and a general lighting applied to the figure. We can begin refining the high lights by adding more on top of previous ones. In the figure below I have added a selection to the baseball cap. Doing the same thing as before with selecting a higher more saturated color, I will apply the radial gradient to this selection. This will give us a more pronounced highlight. If you don't like using the Gradient tool feel free to use the airbrush at 0% hardness, you will have to play with opacity and size settings. I continue to add highlights based on, trying my best to keep them consistent in value. Then I begin doing the same with the skin tones.
Yep more highlights... and we are not done here either (at least not for this image. You could stop here with the highlights if you so desire). Going back over the areas we did before, with smaller selections, and an even lighter hue, its time to add more highlights. This gradual contraction of selections is sometimes referred to as 'cuts'. I am quite sure every colorist has a different method for accomplishing this effect, this is just how I like to do it.
This step is optional. Secondary lighting and reflected light can make a color job much more interesting. It wasn't needed here but I added it for illustration. Take a light blue and making selections along the opposite edge of the primary light source, add in a blue cast using the airbrush. Be careful not to over do it here. Secondary lights or reflected light should be subtle, never more intense than your highlights!
This step is optional. At this stage I am not happy with the background color, yeah it happens. So now we get to use our back up flats channel to select the background and change its hue. Once you have gone to the Backup flats channel and selected the background using the magic wand (w), you will want to restore the visibility back the way we did way back in Step 6. Then with the RGB channel selected bring up the Hue/Saturation/Brightness dialogue (ctrl+u). Click on the 'Colorize' box and then adjust the Hue and saturation levels to your satisfaction.
Well if I haven't lost you up to this point, this is probably where its going to happen. What is about to happen here is me 'correcting' mistakes I made with the render up to this point. I will also be as adding some 'dodged' final highlights for that extra shiny feel. To do this final highlight step set your tool (either the airbrush or gradient) to Color Dodge Mode. Select (using the Eyedropper (I)) the base color from the area you wish to highlight and then fly at it. In this next step I added a gradient to the background just after I finished the changing of its hues. I did this with the background still selected. I then added some final dodged highlights, and made some corrections to the shadow areas and reflected light on the face. TIP: It may help to think about the coloring as 'building up' the highlights one layer at a time.
This step is essential to package up your image. This step is also necessary if you wish to add special effects that cover the line art, like glows, etc. Bring up a selection of the line art channel by Ctrl + clicking on it. Next, invert the selection (Ctrl +Shift + I) and then in the RGB channel fill the selection with Black (Alt + Backspace) if the foreground color is black already). Once you have done this bring up the Apply Image dialog Image >Apply Image. Make sure your source file and channel are correct (channel should be whatever you named your line art channel). Hit OK, when you happy the information is correct.
Now that you have applied the line art you need to delete the line art channel and any other channels you are not going to use. Drag the channels(s) to the trash icon or right click and select 'delete channel'. Now if you want you can go and add glows or glints or whatever you like... have fun and experiment!
You might want to save your file at this point under a different name, just in case you decide to go back into it later.