This unit introduces you to Photoshop ’s Layers , a powerful feature essential in digital image editing.

Layers
One of Photoshop ’s most powerful and most popular features is Layers .  Layers are similar to acetate or transparent paper.  Each Layer  in a Photoshop document or image can contain image data that adds to the image data placed on the Layers below.  Effectively, each Layer is an entire image unto itself within a master image.  By combining these images together, you get what is called a composite, meaning an image composed of many different elements, in this case made up of multiple Layers.  The best way to understand the concept of Layers, how they work, and why they are so powerful is to use them. Open priest and gates from the chapter005 folder in photoshop6xfiles.   Make gates active by {Clicking} on the Image Window  Title Bar.  You’ll notice the color mode is CMYK  rather than RGB.  CMYK is a color space suited for Print production , such as magazines or flyers.  Examine the Channels Palette .  CMYK images are made of a composite of 4 color channels.  Because we are developing for the Internet, we need to convert from CMYK to RGB Image Mode .  Select Image/Mode/RGB Color.  Examine the Channels Palette.  You’ll see only 3 primary color channels and the composite RGB channel.

We’re going to use Layers  to add text to the gates image and add some content from the priest image.  We’ll be using some of the Selections  Tools as well.  We’ll begin by examining the Layers Palette .  {Click} the Layers Tab in the Layers Palette Group .

Layers  Palette
The Layers  Palette  is divided into 8 distinct controls, which include Layers, Blend Mode , Opacity , Layer  Lock Options , and the Layer Style , Layer Mask , New Layer , New Layer Set, New Adjustment Layer, and Trash Icon set.  It’s important to note that Layers have a stacking order, from the bottom up, meaning the Layer at the very bottom of the Layers Palette is the last or bottom Layer.

Layers
Each Layer  contains a Layer Name, Thumbnail, Paint or Linking Toggle, and Visibility Toggle.

Layer  Name
It’s a good idea to name your Layers  for easy reference and organization.  By default Photoshop  names each new Layer  “Layer x” where x represents a number, starting at 1.  If you import a flat image (meaning an image with only one Layer, such as fudog, Photoshop defaults to naming the Layer “Background” in italics.  The Italics indicate that no other Layer can be placed beneath it, in effect locking the Layer as the bottom Layer.  To change the name of the “Background” Layer simply {Double-Click} the Layer and enter a new Name in the Name field.   When you rename the “Background” Layer it is no longer fixed to the bottom of the stack.  To rename any other Layer, select it in the Palette and then select Layer Properties from the Palette’s fly-out menu.  You can also {Double-Click} a Layer while pressing the [ALT] key to rename a Layer.

Thumbnail
The Thumbnail is a visual representation of the Layer ’s content.  By default, Photoshop  uses the smallest Thumbnail size.  To change the size or disable the Thumbnail {Click} the Options  Triangle and select Palette Options.  Check the Thumbnail size you desire in the Layers  Palette  Options dialog box.

or Linking Toggle
When a Layer  is active or selected (by {Clicking} on it) a Paintbrush icon appears in the Toggle box beside the Thumbnail, indicating the Layer can be painted on.  When you {Click} in the Toggle box of an inactive or unselected Layer you “Link” that Layers  content to the current active Layer, no matter where the active Layer is in the stacking order.  Changes in position and various effects you apply to the active Layer are also applied to the LinkedLayer.  A Chain icon appears to indicate Linking.

Visibility Toggle
{Clicking} the Visibility Toggle makes Layers  visible or invisible in the Image Window .  It’s important to note that even though a Layer  may be invisible, if it’s the active Layer or is linked to an active Layer any changes you perform still occur.

Blend Mode
You can select from 17 different Blending options to affect how the image data in a Layer  mixes or blends with other Layers .  Usually you’ll use Normal mode.  Some of the other Blend Mode s  produce interesting effects.  By experimenting and practicing as you compose your images, you will become familiar with the most, if not all the Blend Modes.  You must have at least two Layers in your image to use Blend Mode .

Lock Transparency , Pixels , Position, and Layer
Check the Lock Transparency  checkbox to limit painting and editing effects to areas of a Layer  that are not transparent.   You can also lock the pixels themselves or the position of the pixels by {Clicking} on the appropriate checkbox.

Layer  Style , Layer Mask , New Adjustment Layer, New Layer  Set, New Layer, Trashcan
{Clicking} the Layer  Effect  button allows you to apply prepackaged styles to the content of the selected Layer. 

{Clicking} the Layer  Mask  button adds a Mask to the currently active Layer.  Layer Masks are covered in depth later.

{Clicking} the New Adjustment Layer  button inserts a Layer that allows the designer to apply tonal and color modifications to their image without having to affect the image content in any way.

{Clicking} the Create New Layer  Set button creates a new Layer  set above the currently selected Layer or Layer Set

{Clicking} the Create New Layer  button creates a Layer  above the currently active Layer.

{Clicking}, dragging and releasing a Layer  over top of the Trashcan deletes the Layer.