Lighting Enhancement in Photoshop

By Dan Moughamian and Scott Valentine
Excerpted from Real World Compositing with Adobe Photoshop CS4 (Peachpit Press)

Dateline: February 25, 2008
Version: Photoshop CS4

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The techniques discussed here are used to control visual focus and balance and, in some cases, to add drama. Most are surprisingly easy to create, while providing great visual impact. Lighting layers, as we call them, are typically little more than brush strokes on a layer that rests above your target subject in the layer stack. The layer is then blurred and blended in different ways to give the effect of additional lighting in the scene.

Shaped light. For creative, vignette-like effects, use the Brush tool to create a simple white shape with soft edges on an empty layer. Setting the brushed layer to Overlay causes the painted areas to brighten whatever is beneath them. In the illustration below, the pine tree in the snow was already reasonably well lit, but the shaped light layer adds a completely new dimension and feel to the image. Lighting the tree in this way might make it easier for the tree to fit into a dark composite, because the black and near-black areas can blend together without much interference or extra work.

Original Tree Image (left), Shaped Light Layer (middle), Finished image (top). Creating shaped white brush strokes on an empty layer above your intended “brightening target” and changing the blending mode to Overlay is a simple way to create visually pleasing results.

Rays of light. This is a refinement of the shaped lighting layer technique, where the painted shape looks like a ray from a light source. This variation gives a solid visual direction to a composition and is effective at helping tell a story or set a mood, as shown below. Here we’ve enhanced the drama and emotional effect of a beautiful canyon by adding the beams of light coming down from the side of the image.

We created them by first using the Polygon Lasso tool to draw out the “light fingers,” which we then filled with an off-white color based on the surroundings. From there we softened the edges and lowered the opacity by a large amount to give the appearance of light beams. These types of beams can be used to draw the viewer’s eye to an important subject.

Canyon with Light Ray Selection and Fill Softened Beam Rays Finished Canyon with Subtle Rays Creating rays of light (sometimes called God beams) is surprisingly not as difficult as it might seem using simple brush techniques to shape the beams while keeping perspective lines in mind. In the real world, these beams are wider at the bottom than at their origin in the clouds, for example.

Render Clouds. If we want to add some variation to the landscape, we sometimes use the Render Clouds filter to fill an entire layer with black and white splotches. Once you have found the Blend mode that works best and have reduced the opacity, you can immediately see the effects. Blurring this gives a nice mottled look, and you can use a Perspective transform to make it fit the scene, as shown below.

Once you’ve masked out the parts of your sky that shouldn’t be mottled, you can take a sample from a variegated light source and use that as the basis for your rays. For this example, we took a 1-pixel-wide selection of light coming through the leaves near the top of the scene and stretched it with the Transform tool to simulate the shape of rays we wanted. This approach provides lots of variation and texture for the light, and appears more natural to the scene, since it has a visual anchor.

NOTE: For 3D content, we strongly recommend using the lighting tools built into your application of choice to create photorealistic lighting for your 3D layer content.

The Render Clouds filter can create a mottled light eff ect for landscapes or other shots with large ground planes visible in the scene.

And since we are directing focus with light, you can use the same technique with shadows. The only changes you make are to paint with black and then lower the opacity of the shadow layer. This is usually done to simulate a vignette effect around the edges of photos but can easily be applied to any regions that need individual shadows or darkening. We prefer this method for more detailed work, including creating shadows on objects that exist on different layers.

To create cast shadows on other objects, you will have to rely on your artistic skill to properly assess light fall. This is no easy task for complex surfaces and subjects. We suggest using the Pen tool to draw shadow outlines first, which allows you to adjust the shadow at any time by modifying the path you create. Predicting how shadows will look takes experience, though you can “cheat” a bit with images that have less complex lighting and subject contour. Obviously, the more light sources there are and the more complex the subject, the more difficult it is to create a realistic-looking shadow.

Shadow from layer. Looking at a simple case of a subject isolated from its background, we often create shadows by duplicating the subject layer, locking the transparent pixels, and filling the duplicate with black. From here, we move the shadow layer away from the original and then use the Transform tools to rotate, stretch, and warp the shadow so it can be “placed on the ground” (or whatever surface you’re using) (see below). You can even use Transform > Warp on the shadow to give the impression of a curved surface!

For this example we made sure that the dog’s front foot was placed in a darker, dug-out area of the sand, from which we could give the appearance of a “shadow origin.” Once objects are placed, it is often necessary to experiment with the shadow shape, width, and opacity until they match the surrounding shadows, if there are any. Here our original shadow wasn’t quite blue enough, so we added a bit to the shadow layer using a clipped Photo Filters (cooling) adjustment.

Original Image Composite without Shadow Partially Rotated Shadow Layer, Prior to Final Transforms and Placement The Finished Image For simpler shaped images, creating realistic-looking shadows is a fairly easy process once you commit a few basic steps to memory.

Shadows the hard (but more accurate) way. Sometimes it’s necessary to create shadows from scratch. Usually this is done with the help of Ruler Guides and the Pen tool.

The gladiator below was originally standing on a street with somewhat diffuse lighting. The base shot of the ruins has strong light at a severe angle, just in front and to the right of the photographer. That meant the shadows would be prominent so they had to be very precise. After placement of the gladiator smart object was complete, the major challenge was building the shadows.

The first task was to figure out the angle of light fall, using one of the columns as a reference. Using the Pen tool, we constructed a triangle that went from the top of a column to the peak of the shadow, then back to the base of the column and up to the top again. That gave approximate angles for a shadow on a flat surface. However, the stairs can be approximated as a sloping plane to determine the length of the shadow. As the plane slopes downward, the shadow gets longer. Next we moved the path node down along the shadow line until it reached the stairs. That also rotated the bottom line.

TIP: If you need to draw your own shadows by hand, it helps to first make a temporary sketching layer so you can keep track of light direction and intensity with notes or markings.

Creating shadows along undulating or geometrically contoured surfaces takes more eff ort but is possible using the Pen tool as the basis for your shadow shape.

When a shadow is cast down stairs, the length of the shadow is the same whether it is cast on the stairs or a flat plane. What changes is that the tops of the steps are flat, and there are right angles to deal with. We filled the outline of the gladiator with black on a new layer, then transformed the shadow, stretching and applying a little perspective until the top met the right point on our guide, and the bottom was anchored at his feet.

Using the Pen tool again, we outlined the shadow, making sure to put transform nodes where the shadow crossed a right angle. Because the shadow crossed several steps, we had to treat each flat plane of the stairs individually, dragging one node at a time down the face of the steps. At the leading corner for each step, the shadow stayed with the bottom line guide. But at the inside corner, the node moved that part of the shadow to the right.

Once the outline was completed, we took a look at the other shadows and adjusted the density and color of our new shadow to match. After that, we applied a layer mask to our shadow layer and filled it with a gradient to use as a guide for a very slight Lens Blur treatment. The masking proved to be difficult at the transition from shadow to dark, so after we finished the blur and added a little noise, we created a flat, merged layer above everything and used the Patch and Healing tools on the seams.

3D Shadows. For the time being, creating shadows that are cast from your 3D Photoshop models or layers onto a 2D layer or image plane is a very complex and time-consuming task—so much so that we recommend that you not attempt to create 3D-generated shadows from Photoshop. Instead, duplicate your finished 3D layer, rasterize it, and then create the shadow in the same ways noted earlier.

By this point, you have taken the time to make sure all your subjects have been placed into the scene with a scale, a relationship to one another, a level of focus, perspective, and believable lighting and shadows. The scene now looks real (or surreal if that’s your goal) in the basic sense. But what it lacks might be a bit of moodiness, humor, or just some intangible quality that you can’t quite put your finger on, but you know it when you see it.

It’s time to make the (frankly random) small changes that every image requires to become that much more believable. These changes can include everything from tweaking the color and shininess of a wood-grained dashboard using techniques such as painting with Vivid Light to making the clouds in your scene look a bit more ominous, to warping a tiny corner of your faux shadow into the crack in the sidewalk so it looks a little more “there.”

Many compositing artists will benefit from taking a few hours or even a few days off and not looking at their “almost-finished” work. Invariably, when you come back and look at it again, you will see variations in the color and lighting of your subjects (or the scene as a whole) that just don’t quite look right. While it is somewhat subjective, this phenomenon is true whether you’re retouching photos, drafting an illustration, or compositing 2D and 3D elements together.

Color and tone tweaks. Probably the most common “extra tweaks” that any image needs (particularly images with outdoor or otherwise complex lighting) are a few added brush strokes here and there to make the subject “pop” a little bit more. For this example, shown below, everything looks great for the most part, but we noticed that some of the houses were somewhat dull in appearance. They’re not underexposed or unsaturated... just a bit lifeless. (And, yes, we know that houses are not alive!) To remedy this problem, we used the Brush tool and Option-clicked (Alt-clicked) the regions we wanted to liven up, which gave us a color to work with. From there we reduced the brush opacity to less than 15 percent, softened the edge a bit, and went to work on sprucing things up!

Before Brushed Enhancements After Brushed Enhancements Using the Brush tool in combination with sampled colors and various blending modes painted at lower opacities can help lend that extra something to your subjects.

Mixed bag. Another useful technique comes into play when you want to mix regions of grayscale detail with color detail. For example, perhaps some part of your layer or concept is so striking that you want to maintain the detail around it but focus solely on the subject in question without throwing all sorts of beams of light on it or warping it. For these situations, the Black & White adjustment layer, combined with a layer mask to isolate the color regions, can have an impressive effect (see below). And, by using a mask to selectively apply your settings, you can also modify the amount of those settings via the opacity.

Without Black & White Adjustment With Black & White Adjustment The Black & White adjustment layer has many potential uses in compositing as well as in traditional photographic retouching.

Auto-Align, Auto-Blend layers. For the simplest of all composite images—panoramic photographs—the first compositing steps are often the last. Earlier in the chapter we mentioned the usefulness of smart object stacks as a means of finishing your panoramic images quickly. But the real power of Photoshop CS4 comes to light when you use the Auto-Align Layers and Auto-Blend Layers commands (both in the Edit menu) first to place and transform the images in your stack and then to seamlessly blend their tonality and color (blending dissimilar regions of sky being the most common example).

The Auto-Align Layers dialog box (see below) offers some new options in Photoshop CS4, but we’re ashamed to admit that the Auto option works so well that we often try that first without experimenting with the other methods of layer alignment. Fundamentally, what these alignment options do is examine each image layer for common visual details; then Photoshop overlaps the layers using these details as “registration points” and, finally, uses various transform algorithms to remove the distortions that would otherwise prevent a smooth-looking panoramic scene. After building our smart object stack of source files, we typically perform this step second.

Auto-Align Layers Dialog Box Aligned Files without Blended Tones or Colors The Auto-Align Layers dialog box makes it simple to create the initial alignment for your panoramic composite image.

Third, we use the Auto-Blend Layers dialog box to smooth out the uneven tonality in the bordering image regions and handle any color differences (below). Since we always align the images prior to this step, we select the Stack Images and Seamless Tones and Color options.

When using these two features, it really is quite amazing how “automatic” the results can be, even with very complex panoramic composites, such as the ones shown below, which contain details along the ground plain that could easily confuse lesser panoramic software.

Auto-Align Layers Dialog Box Aligned Files without Blended Tones or Colors

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Excerpted from Real World Compositing with Adobe Photoshop CS4 by Dan Moughamian and Scott Valentine. Copyright © 2009. Used with permission of Pearson Education, Inc. and Peachpit Press. All rights reserved.