Photoshop Fundamentals: Working wih Transparency

Adapted from The Non-Designer's Photoshop Book (Peachpit Press)

By Robin Williams and John Tollett

All layers, except Background layers, are transparent. Even if a layer is filled with pixels, such as an image, a fill color, or both, the layer itself retains transparency capabilities, allowing other layers below it to show through when pixels on the top layer are erased or masked.

You can give any layer a degree of transparency by adjusting its opacity. Whenever necessary, the Background layer can be converted from a non-transparent layer to a regular transparent layer.

Transparent layers are what provide the remarkable fexibility and creative potential of Photoshop—it’s important to understand how they’re working for you!

What is Transparency?

With the exception of “Background” layers (which are not transparent), image layers consist of opaque pixels against a transparent background. The transparent areas of a layer are represented by a gray and white checkerboard pattern. In the example below, the layer of Jimmy and Scarlett is above a layer that contains an image of flower blooms. Where the background of the top layer is erased (where you see the checkerboard), the flower bloom layer can show through. In addition, layer opacity can be adjusted to any degree of transparency, which opens up all sorts of visual effects possibilities.

Transparency Preferences

Photoshop’s preferences allow you to decide how you want to be reminded that a layer is transparent, via a checkerboard grid (or not).
  1. From the Photoshop menu, choose Preferences > Transparency & Gamut… (PC: Edit > Preferences > Transparency & Gamut…).
  2. From the pop-up menu, choose a preset Grid Size and Grid Colors for the transparency checkerboard. To create custom grid colors, click the color swatches (shown below).

    To hide the transparency checkerboard, choose “None” for Grid Size.
    Click ok.

Lock the Transparent Pixels

When a layer contains both an image and areas of transparency, you can protect the transparent areas while you edit the image. For example, you might have an element on a layer, such as handlettering (shown below) that you want to add brush strokes to, without letting the brush strokes touch the background area. Locking the transparency enables you to do that. Photoshop refers to transparent areas as “transparent pixels,” so when we say “Lock transparent pixels,” we mean lock the transparency so that it’s protected and preserved.

  • Create a new layer: click the Create new layer icon at the bottom of the Layers panel. Or from the Layer menu, choose New > Layer….
  • Select the Brush tool and paint a word on the layer, as shown below.

  • Click the Lock transparent pixels icon (called-out above).
  • Choose a darker paint color, then brush across the layer to add brush strokes on top of the word. Because the transparent pixels are locked, the new color you paint does not affect the transparent areas, just the visible ones.

Lock Image Pixels and Position

There are four “Lock” icons in the Layers panel; the first one is explained above. The other three Lock icons affect layer transparency in these ways:

  • Lock Image Pixels prevents visible pixels on the layer from being altered in any way.

  • Lock Position prevents visible pixels from being moved.

  • Lock All locks transparent pixels and pixel position (the visible image pixels can’t be moved or altered in any way).

When a layer is partially locked (when just one or two of the “Lock” items are selected), a white lock icon is shown on the layer (below-left).

When a layer is fully locked (when the “Lock All” icon is selected), a black lock icon is shown on the layer (below-right).

You can unlock the transparent pixels of a selected layer at any time in order to work in the transparent areas of the layer.

Use the Fill Setting for Special Effects

While the Opacity setting in the Layers panel determines how transparent everything on the layer is, the Fill setting, also in the Layers panel, affects only pixels, shapes, or text. It does not affect the opacity of layer effects that you’ve applied, such as drop shadows, bevel & emboss, stroke, etc.

Fill Image Pixels with Color

To color the image pixels on a transparent layer with the current Foreground color, without locking the transparency: Select the layer, then press Option Shift Delete (PC: Alt Shift Backspace).

To color the image pixels on a transparent background with the current Background color: Select the layer, then press Command Shift Delete (PC: Control Shift Backspace). This is similar to “Lock transparent pixels” mentioned above.

Change Background Layer Opacity

The opacity of a Background layer cannot be changed; you must convert the Background to a regular (transparent) layer. Do one of the following:

  • Double-click the Background layer; click ok.
  • Drag the Background layer’s lock icon to the Trash icon.
  • From the Layer menu, choose New > Layer From Background…; click ok.

Save as TIFF with Transparency

You can save an image as a file that preserves its transparency to maximize design choices when it’s placed in a page layout application such as InDesign.

  1. From the File menu, choose Save As….
  2. In the “Save As” dialog, set “Format” as TIFF.
  3. Deselect the “Layers” option, to make the file smaller.
  4. Choose a name and location for the file, then click “Save.”
  5. In the TIFF Options dialog (below), check “Save Transparency.”
  6. Place the TIFF file in InDesign and enjoy the design freedom of working with a transparent background image.

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The Non-Designer's Photoshop Book by Robin Williams and John Tollett. Copyright © 2011. Used with permission of Pearson Education, Inc. and Peachpit Press.