Τρίτη, 22 Οκτωβρίου 2013

Photoshop Tutorial: Advanced Colorization Technique

Colorizing a B&W image is one of the most satisfying endeavors you can pursue in digital imaging. I find bringing new life to a classic image to be quite exhilarating.

We'll use this themepost (from the HxH Pleasantville - Martha Hyer contest) for demonstration purposes:

Note: I use Photoshop CS5e on a PC. These techniques work particularly well for me, but by no means should they be considered the only or best way to do things. As usual you are encouraged to experiment to discover what works best for you.

1: Prepare your source

The chances of your B&W source being perfectly suited for coloring right off the bat are slim. The source we are using here is very close, but it still can use some preparation and clean-up before adding any color.

The first thing to do is prepare the source image for coloring. This includes extracting as much detail as possible in both the highlights and shadows; removing dust spots and/or scratches; repairing damage; taming unruly noise; sharpening; correcting luminance values; etc. It's much easier to attend to these issues before any color is applied!

Remember as a kid, you were given a coloring book and a nice new box of crayons? You were taught to "stay in the lines"! Well, that is still the case with digital coloring. Now, however, we can get some help by using masking. As you might expect, the quality of your coloring effort will depend greatly on the quality of your masking. So next, let's make some masks!

2: Make selection groups
There's a good chance that your project will end up having lots of layers. I used just short of 60 layers to colorize this photo. Sources with more subjects and details could easily grow to several hundred layers. It's a good idea to organize your workflow from the get-go.

I initially divided this image into 4 main areas: the model, foreground, background and sky. Create a new layer group for each main area. It's wise to label each appropriately. Working near to far*, use your preferred method to make a selection for each main area. For maximum accuracy, I generally use the pen tool. Create a mask from your selection on each of the groups.

*Why select near to far? This way you'll never need to go over the same line twice. E.g., first I selected the model (in front). Next I selected the tree (behind her), but just drew roughly through the model. To finish, I just subtracted the model selection from the that of the tree! Similarly, you can add or intercept selections to get the needed result.

3: Make sub-selections within groups
Next, within each group, continue by creating sub-groups and drawing selections/making masks of specific parts. In the model group I selected: pants, belt, blouse, jewelry, hair, skin. Create sub-sub-groups for those parts that will need even more detailed selections. E.g., in this case, additional selections were made within the skin sub-group for: lips, teeth, eyes.

After you've suffered this rather tedious selection/masking marathon, you will have a nicely organized layer tree in which you'll be able to quickly find virtually any part of the image. This will pay big dividends later on.

Good grief! After all that work, my B&W image still looks the same! Can I start coloring now? Please?

Hold your horses! We're getting there, but first let's explore a couple of color application techniques that you may have never considered.

One commonly used method of coloring adds a hue/saturation (H/S) adjustment layer with the colorize option checked and the hue adjusted as desired. This is quite effective in many cases, but it is certainly not the best way (IMHO) - especially if you desire a bit more control over the result.

4: Using gradient maps to apply color

Let's consider coloring skin. Rather than using H/S, I suggest using a gradient map (GM) adjustment layer in normal mode. The following example shows a regular black to white value gradient. The top half was colored using H/S. The lower half was colored with a 5 color GM in normal mode.

They are indeed similar, but look closely at the darkest and lightest values. The pure blacks and whites in the top half remain black and white. This is because the H/S method (or color mode painting) effects these values less and less as they become more pure. The GM example however, produces a smoother transition and those pure blacks and whites have now taken on a hint of color.

When applied to an actual photo, the difference is even more apparent.

The H/S method restricts you to one and only one hue. Of course you can paint on a color mode layer using several carefully selected colors, but in either case, those pure blacks/whites will simply not accept any color.

On the other hand, the GM used starts with 5 colors. Each can be adjusted for hue, saturation and lightness individually. You can remove colors or add as many as you like. And you will have complete control over the color of those extremely dark or light values.

While great for skin, a GM can be used for any coloring task. For a simple single color need, start with a black to white gradient and add a stop of the desired color somewhere in between. Adjust to suit. Try a GM for duotone, tritone, quadtone. Of course you can also change a GM adjustment layer to any blend mode that produces the desired result, or use blend-if (see next).

I suggest that you give the GM method a try. If you want to play with the same map I've used here, the formula follows:

Plug these values into a new GM and save it for repeat use. Apply it and experiment with changing the HSL, location and mid-point location for each color stop. Once you get the hang of it, I believe you'll become a believer as well!

5: Using blend-if

Perhaps one of the most powerful and versatile tools you have at your disposal is "Blend If". You can find it at the bottom of Blending Options (in the Layer Style dialog).

If you are not familiar with this tool, I highly recommend learning how to use it and what it can do!

Let's put it to good use in the sky group of our demo image:

Select and expand the "sky" group. (I've blacked out the rest for emphasis.)

First I want to add some color to the sky:
  1. Add a new normal mode layer and fill it using the gradient tool (light yellow to light blue). Since the group is masked, this will only show in the sky.
  2. Reduce the layer opacity to around 40%.
  3. Since we don't want the color on the trees we'll use Blend If to let the darks pass through. With the gradient layer active, open the Blending Options dialog. Alt-click on the right half of the black arrow in the underlying layer sliders and drag it all the way to the right. Drag the left half to the right until all the color is gone from the darker tree branches.

Now I want to make the trees green:
  1. Add a normal mode GM adjustment layer. I made a gradient from a darker green to a greenish gold for some variation.
  2. Since we want to color only the trees we'll again use Blend If to let the brights pass through this time. With the GM layer active, open the Blending Options dialog, Alt-click on the left half of the white arrow in the underlying layer sliders and drag it all the way to the left. The other half can stay at the right end.

Next I want to add more color variation to the tree leaves and browns to the branches:
  1. Add a new color mode layer. Using a soft brush, simply paint in earthy colors over the leaves and browns over the branches as shown. As you can see, there's no need to be too precise.
  2. Since we want the color only on the trees we'll use Blend If to let the brights pass through once again. Alt-click on the left half of the white arrow in the underlying layer sliders and drag it all the way to the left. Drag the right half to the left a bit until you are happy with the blending result.

And there you have it. We've added some realistic colors to the sky and the trees very quickly without any additional masking required, all thanks to "Blend If"!

6: Colorize

Finally, it's almost time to start adding some color! BUT WAIT! Before adding colors, it's a good idea to have a pretty good idea of what colors to add. This is seldom an easy task. While much of the time it boils down to educated guessing, I suggest doing some research. If your source includes people, you may wish to search for and note similar period clothing/costuming. If a celebrity, you can look up their eye color, hair color, etc. If a scene from a classic movie, watch the movie if possible for contextual clues. Look for illustrated color posters for ideas. Collect examples to reference once you begin colorizing.

Although color theory is beyond the scope of this tutorial, it wouldn't hurt to be familiar with the basics. Use color to support the atmosphere and theme of the image. The main thing to keep in mind is that you will want to choose colors that are honest, realistic and logical.

You should now be well armed and ready to colorize. Since you have a perfectly structured layer tree and have pre-made almost all needed masks, this step should move along very quickly. Work through your layer tree and colorize (within your preconfigured groups) by main area. There's no need to be too critical as you proceed right now. Just lay down your base colors. The fact is, the result is simply not going to look all that good until everything is colored. Also, a good rule of thumb is: Colorize absolutely everything. Even grays and whites have a hint of color introduced from lighting or reflected off surroundings.

Once you have all your basic coloring applied, you can evaluate the overall image. If any of the colors you chose do not seem quite right, return to that group and adjust accordingly. You can add as many new layers to any group as needed to get the desired result as you work.

7: Refining

The next step is to add all the tasty details and enhancements that will make your image POP!

Do you want to slightly change the coloring of a particular part? Do you want to add some color variation or accent colors? Do you want to make selective contrast, brightness, sharpness adjustments? Since you have masks on hand for virtually everything in the image, all of this and more can be done easily and precisely.

I typically create a new merge all layer (named Details) on top of my layer stack, as if to start afresh. I'm now essentially retouching a new full color image! You can continue to edit non-destructively if you wish. I generally will just add the layers I need for a particular refinement, and when satisfied, merge down to the Details layer. This simply avoids the accumulation of too many additional layers.

8: Dodge & Burn

One of the most effective enhancements you can apply to your image is the standard retouching method known as "dodge and burn". Your goal is to strengthen the perception of depth (aka sculpting) by selectively brightening or darkening the existing and logical highlights and shadows.

Contrary to what you might immediately think, this process doesn't involve the use of Photoshop's basic dodge and burn tools. Rather, it is done non-destructively on an independent layer.

On top of your layer stack, add a new layer filled with 50% gray with a blending mode of overlay (or softlight for a more subdued effect). On this layer you will paint with a small, soft brush set to 1-5% flow. To brighten, stroke the area with white, gradually building density as desired. Conversely, to darken, paint with black.

After doing some judicious painting, your layer might look something like this:

In context, here is the effect this effort will produce:

9: Finishing touches

Are we done yet? Good question, but not one easily answered. I often declare I'm "done" a dozen times, but I seem to continue to find minute things that I just have to refine.

You're best bet is to save a flattened copy of your image and perhaps make a print. Shut down your editor and walk away. Give your eyes something else to look at besides your computer screen for a while. Some time later, return and open your image again. View it full-screen with no editor junk in the way. Step back and simply ask yourself, "Does this look like a genuine color photograph?" Look at the print and ask the same question. Ask others as well. If you cannot honesty answer in the affirmative, there's a good chance you are not quite done yet!

I think mine is done!

See also


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