Blending an image with the background

The blending mode controls how pixels in an image are affected by painting and editing tools. It’s helpful to think in terms of the following types of colors when visualizing a blending mode’s effect:

• The base color is the original color in the image.

• The blend color is the color being applied with the painting or editing tool.

• The result color is the color resulting from the blend.

Throughout this lesson, you will learn how to specify a blending mode for a layer in the Layers palette and for a tool in the tool options bar.

For color illustrations of the different layer blending modes available in Photoshop and ImageReady,, see figure 8-1 of the color section. For descriptions of each blending mode, see “Selecting a blending mode” in Photoshop online Help.

You’ll use the Multiply blending mode to blend the white background of a tree outline on one layer with the opaque layer behind it.

1.	Choose File > Open, and open the 08Start.psd file in your Lessons/Lesson08 folder. The file opens, showing you one of the layers that has been prepared for you: a mottled blue-and-white texture. This coloration covers the entire image window, simulating a thin layer of wispy clouds against a deep blue sky.
2.	In the Layers palette, click the empty box to the left of the Tree layer set to place an eye icon (), which reveals that entire layer set in the image window.
3.	Again in the Layers palette, click the arrow next to the Tree folder icon to expand the layer set. Two layers are nested in the set: an Outline layer and a Bark layer. An outline drawing of tree branches against a white background now blocks part of the sky.
4.	Select the Outline layer in the Tree layer set. Then, at the top of the palette, use the pop_up menu to change the blending mode from Normal to Multiply. The white background disappears, and the brown paint on the Bark layer shows up. The Multiply blending mode calculates the color for each pixel by multiplying the color information in each channel (such as R, G, and B) by the color channels in the paint pixels. As a result, painting in Multiply blending mode creates colors that are darker than the original colors.
5.	With the Outline layer still active, change the Opacity value in the Layers palette to 30%, to soften the outline so that it looks more artistic and less cartoon-like. You’ll make more adjustments to the appearance of the tree limb in the next procedures.
6.	Choose File > Save.

Painting shadows and highlights in nontransparent areas

In this part of the lesson, you’ll lock the transparency on the Bark layer. This restricts your painting on the layer so that you can add shadows and highlights to only the tree itself. Because all the transparent areas are protected, you don’t have to worry about any paint strokes spilling onto the background outside of the tree outline.

There are two techniques for protecting the transparent areas. One is to select the layer you’ll paint on and use the Lock Transparent Pixels option () in the Layers palette. The other technique, which you’ll use here, is to create a new layer and then group it with the previous one. When you apply brush strokes or effects to a layer that is grouped with a second layer, those brush strokes or effects apply only to pixels of color on the first layer. (Any transparent areas will be unaffected.)

1.	In the Layers palette, select the Bark layer (in the Tree layer set), and then select New Layer from the Layers palette menu. (Don’t use the New Layer button this time.)
2.	In the New Layer dialog box, type Highlights and select the Group With Previous Layer check box. Then click OK. The Highlights layer appears with a small arrow pointing to the Bark layer, indicating that these two layers are grouped. (This arrow may be difficult to see while the Highlights layer is selected.)
3.	On the Swatches palette, select a warm brown color from the bottom row of the swatches, using a color that is somewhat darker than the tree-bark color.
4.	In the toolbox, select the brush tool. Then use the Brushes palette to select a brush, such as the Soft Round 21-pixel brush.
5.	Make sure that the Highlights layer is active in the Layers palette, and then paint shadows on the right sides and lower edges of the branches of the tree, as if a light source is outside the image to the upper left. Also paint shadows into the gnarly areas of the main branch. As you paint, you don’t need to worry about painting outside the tree area (because those areas are protected) or that the effect isn’t subtle (because you’ll adjust that later). You can adjust the brush size and opacity of the paint as you work, using the settings on the tool options bar. To change the brush size on the fly, press left-bracket ([) to move to the next smaller brush size; press right-bracket (]) to switch to the next larger brush size.
6.	In the Swatches palette, select a brown color that is lighter than the original bark color, and use it to paint highlights on the upper and left sides of the branches. Then select white, and add touches of bright highlights to some of these areas.
7.	When you are satisfied with the highlights and shadows (although the results are still not subtle), choose File > Save.

Smoothing the edges of a stroke

Now you’ll use the blur tool to soften the edges of your paint strokes, smoothing out the color transitions between the brown shadows, the underlying bark, and the bright highlights.

1.	In the toolbox, select the blur tool (). Then, in the Brushes palette, select a small brush, such as the Soft Round 21 brush you used earlier. Make sure that tool options bar is set with Mode at Normal and Strength at 50%.
2.	Make sure that the Highlight layer is active (selected) in the Layers palette.
3.	Drag the blur tool brush over the shadows and highlights of the tree branch to soften the color transitions. (It may be helpful to zoom in to see the results as you blur the image.)
4.	As you blur the image, try adjusting the Strength option value in the tool options bar. If you don’t like the results one percentage produces, choose Edit > Undo, and try a different one.
5.	When you are satisfied with the blend of highlights and shadows, choose File > Save.