Creating Photoshop Images in Layers

Creating and Managing Layers

Worrying about any of the settings and features having to do with layer information is really wasted effort if you are working with only one layer. If there isn't more than one layer, there is no opportunity for layer interaction, so layer controls will be inoperative. There are innumerable opportunities to take advantage of layers and their controls but you have to create additional layers to take advantage of that opportunity. At times you will have to create layers and sometimes they will be created for you. Understanding the relationship between how to create, control, and activate layers is imperative for proper image editing and development.

Creating Layers

A number of user actions will create a new layer. These include

• Pressing (Shift–Cmd–N) [Shift+Ctrl+N]

• Clicking the New Layer button on the Layers palette

• Pasting a copied image area (either within the same image or in other images)

• Duplicating a layer with the Duplicate function (on the Layers palette or the Layers menu)

• Dragging a layer to the New Layer button

• Dragging a layer from another image

• Entering type by clicking the Type tool on the image

• Creating a New Fill Layer (Layer, New Fill Layer)

• Creating a New Adjustment Layer (Layer, New Adjustment Layer)

• Rendering Layer effects (Layer, Layer Style, Create Layer)

Creating a new blank layer with either of the first two actions in the preceding list will place a new layer above the currently active layer, and will open the New Layer dialog box (see Figure 3.2).

Figure 3.2
In the New Layer dialog box, you get to choose options for the layer you are creating, including the layer name, grouping the new layer with the previous, selecting a Color coding for the layer in the palette, choosing a Mode, and setting Opacity.

Layers can be created from selections or by duplicating layers using the keyboard shortcuts seen in Table 3.2.

Table 3.2 Shortcuts for Layer Creation

You will want to create a new layer every time there is image information you need to isolate from other portions of the image. Isolation is useful for managing image and element blending, as well as aiding in certain types of corrections. Layers provide unique opportunities to indulge complex image arrangement and interaction.

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Layering Tool Applications

When doing just about any correction to an image, you will want to use additional layers to allow you several options. If making the correction to a separate layer, you can quickly compare the changes by toggling the view for the changes off and on (before and after), and you will have unprecedented options for blending, merging, smoothing, and otherwise optimizing the incorporation of what you have done in the correction. If you don't think the changes are optimal, you can store the changes and duplicate them to yet another layer to see whether you can improve on them—and you can apply layered changes to the changes! Considering this versatility, the one-shot correct-it-all-in-one-layer approach is not recommended.

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If you create a layer and have trouble applying new tools and effects, there can be several things going wrong. See "Getting a Layer to Work" in the Troubleshooting section at the end of this chapter.

Merging Layers

On the other side of layer creation is Layer Merge. Merging is putting together information from two different layers so that the layer information is no longer separate. Merging can be used to combine layers that need not be separate, such as several text applications over an image to which you will want to apply the same effects. In this case you will have to render the type before merging, but merging will help you manage effects and conserve memory.

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Note - Layers are tremendously flexible and add a lot of possibility to manipulating images; however, they also require a significant amount of memory to maintain. Keeping layers to a minimum by combining Layers via Merge whenever it will not affect your ability to work on the image can free up memory and maintain a more efficient working environment.

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There are a number of options for merging layers and all appear on the contextually sensitive Merge section of the Layer Menu. The menu adjusts options to those that are most probable considering the layer that is currently active. The selection by the program is based on a hierarchy of what Merge variations are possible, approximately in the order that follows (from most likely to be superceded):

• Merge Down—Merges the currently active layer into the layer immediately below. Both the active layer and the layer immediately below must be visible.

• Merge Group—Merges all the layers in a clipping group. The bottommost layer of the group must be active.

• Merge Linked—Merges all linked layers provided the linked layers are all visible and not part of a clipping group (all parts of any group must be part of the link).

• Merge Visible—Merges all visible layers. The active layer must be a visible layer.

• Flatten Image—Is essentially the ultimate Merge in that it will combine all layers into a single layer. A warning will be issued when the function is invoked if any layers are hidden letting the user know that all hidden layers will be discarded during the flattening.

Activating Layers

Active layers are really the layers that will be targeted to accept the changes you implement in the course of working with the image. Simply stated, an active layer is the one that is highlighted in the Layers palette. The area of the Layers palette that contains the layer description will be in the highlighted color, and the Paintbrush icon will be to the left of the layer thumbnail. This layer will accept application of any tools or functions invoked.

To activate a layer to work on, simply click it in the Layers palette. Layers can also be activated using keystrokes. This will move up and down through the visible layers or jump to layers at the top and bottom of the stack. Combinations of these keystrokes can help you quickly navigate between layers when working on an image. See Table 3.3 for a listing of the keystrokes.

Table 3.3 Keystroke Layer Navigation

After a layer is activated, changes can be made to the image content using any of Photoshop's tools that affect pixel information, so long as the tool or function is available. Layer information can be moved within the layer, both by arranging layer order and by horizontal and vertical positioning of the layer information. Positioning can be independent from or in unison with other Linked Layers, Clipping Groups, or Layer Sets.

Linked Layers

Linking is a means of managing layer content by grouping and linking the content of selected layers. Linked layers will be affected by layer content movements in the image plane and Transformations applied to any layer in that group, but will not be affected by movement of the layer in the Layers palette. The Layers will move in unison and will not have to be realigned or moved individually to maintain alignment with one another. Linking layers provides noncontiguous control of layers that spans Layer Sets, Clipping Groups, and visibility.

To link a layer to another layer, make one of the layers that will be linked the active layer. This will automatically place the paintbrush icon in the box immediately to the left of the thumbnail. Next, click the link indicator box on the Layers palette immediately to the left of the layer you would like to link it to. A Link icon will appear in the box where you clicked, indicating that the layer is linked to the active layer.

Items linked together will always appear as linked to one another: Anytime one of the layers in the Linked group is selected as active, the Paintbrush icon will appear next to it showing it is the active layer, and the other links in the group will display the link icon. These links appear in the grouping regardless of which layer is active or the order they were created in. In other words, if you link Layers 2 and 3 to Layer 1, Layer 1 will have the Paintbrush icon at the time of linking, and 2 and 3 will have Link icons. When you select Layer 2 as the active layer, the Paintbrush icon will appear next to it, and the Link icon will appear next to Layers 1 and 3. These links will remain in effect until they are removed.

All movements within the image plane and transformations will affect all linked layers equally. Any number of layers can be linked in whatever order (contiguously or noncontiguously within the stack), and links can be terminated and activated at will. To remove a link, simply click the Link icon when another layer in the linked group is active. This will remove the link only from the layer from which the icon was removed. A quick means of linking a series of contiguous layers is to hold the Shift key down while holding down the mouse button and dragging the pointer over the link boxes. To unlink by clicking and dragging, hold down the (Option) [Alt] key.

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Aligning Layer Content

Pixel content in linked layers can be aligned and distributed using the Align and Distribute commands on the Layer menu or the alignment buttons on the Move tool options. Two or more layers have to be linked to use the Align feature and three or more must be linked to use the distribute feature (see Figure 3.3).

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Figure 3.3
Layer content can be arranged quickly by linking the items you want to align and clicking the appropriate button on the Movement Options bar for alignment or distribution.

Layer Sets

Layer Sets are a brand-new feature in Photoshop 6 (see Figure 3.4). They are a means of grouping collections of layers that need to be maintained in a particular order. This provides a means for easy movement of the group (between images or in the layer order). Layer Sets also allow for the contents of the Sets to be collapsed and expanded in the Layers palette view. Viewing and hiding in no way affects the content of the set.

Figure 3.4
The collapsed Layer Set makes it easier to view the remaining layers. This can be moved as a group within the image and without, deleted as a group, or viewed by expanding.

Layer Sets can be Masked or clipped as a group by applying a Mask and/or Layer Clipping Path to the Set. The content of the Sets must contain contiguous layers, unlike linked layers, but can contain linked layers and Clipping Groups. Sets are a higher level of order and cannot be used as part of a Clipping Group.

Creating Layer Sets

To create a Layer Set, you can either create the folder for the set and then drag layers into it, or link the layers that you want in the set and choose New Set From Linked from the Layers palette pop-up menu. Dragging the layers to a set you create is clumsier than linking the layers and then creating the set if the layers already exist because you have to drag individual layers in one at a time. Layers dragged into a Set folder stack from the top down unless dragged to a specific spot: Each layer you drag in gets added to the bottom of the stack if you just drag it to the folder. This is counter to the way layers generally work, which is from the bottom up. You can rearrange the layers after they are in the folder—or you can drag them one at a time to the spot in which they belong in the order. If you use New Set From Linked, the Linked Layers will retain the layer order they had when the Set was created. To create an empty set, click the New Set icon at the bottom of the Layers palette.

Using Layer Sets with Channels

Another use for Layer Sets, and a rather unique feature for layers, is that the effects of layer Sets can be targeted to specific channels. For example, if working in CMYK, you can create a Layer Set that will affect only the cyan and black channels while not affecting the content of the yellow and magenta channels—even if there are yellow and magenta components in the layers used for the Layer Set. To Target a specific Channel, highlight a Layer Set that you have already created and choose Layer Properties from the Layer Menu or Layers palette pop-up. The Layer Set Properties screen will appear (see Figure 3.5). Simply uncheck the boxes by the primaries that you do not want the changes to apply to.

Figure 3.5
This feature can be handy for some color changes where the color change is content specific, such as redeye. In the case of redeye, limiting the color change to the red Channel in RGB or the yellow and magenta in CMYK might help you make a color change targeted to the red while maintaining other color integrity.

Clipping Groups

Clipping Groups use the bottommost layer in a group as a mask and apply the content of the layers above (within the group) to the image based on the order of the layers. The base layer of a Clipping Group clips the other layers in the group based on its transparency.

Clipping Groups define a result based on what are essentially substacks of layers. Where an image is the result of all the stacked visible layers on the background, Clipping Groups use the base of the group as the background. The grouped layers use the bottom layer as a clipping path or mask for the grouped layers above it based on its areas of transparency. Unlike the background of the image, however, Clipping Groups can appear anywhere in the layer order.

Using a Clipping Group is like using a Layer Mask or Layer Clipping Path. In fact, Layer Masks, Clipping Groups, and Layer Clipping Paths all essentially do the same thing, although they each do it a little differently.

To create a Clipping Group:

1. Create or open an image with at least two layers in a stack (in addition to the background if you have one).

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Note - The bottom layer should probably have some transparent or semitransparent areas.

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2. Make the upper layer of the two you are using for the Clipping Group active.

3. Group the layers by pressing (Cmd-G) [Ctrl+G]; the lower layer's transparency clips the information from the upper layer (see Figure 3.6).

Figure 3.6
In this series of images, the top layer is placed on the second layer. When they are grouped, the result is that the base layer of the Clipping Group cookie-cuts the image lying above it. The area of the image above that falls to where the base layer is 100% opaque stays, while the rest falls away.

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Note - If you select the grouping command from the Layers menu, it is called Group With Previous.

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The top layer in the pairing will have its content confined by the opacity of the lower layer. Another method for applying a Clipping Group is to link the layers. When one of the Linked layers is selected, Group Linked can be selected from the Layers menu (actually the same command as Group With Previous; its name changes to fit the context).

Layer Masks

A Layer Mask, like a Clipping Group, helps redefine the content of the layer. The masks block out layer information, somewhat like placing a stencil on the layer. One notable difference between a mask in Photoshop and a stencil is that a mask can be semiopaque.

To apply a Layer Mask:

1. Create a selection of the area you would like to mask. As an alternative, a selection can be loaded from one you have already created or another Channel can be loaded as a Mask.

2. After the selection is active, choose either Reveal Selection or Hide Selection from Layer, Add a Layer Mask menu. Reveal selection will create a Mask for the layer that masks the unselected portion of the image, revealing the selected area; Hide Selection will mask the selected area of the image.

Masked areas appear black in the layer Mask. Figure 3.7 shows the result of applying a Layer Mask.

Figure 3.7
The Layer Mask in this case was loaded from a selection adjusted to fit the subject's eye area. Note the effect of the inner ring in the selection on the result. When the mask is applied to the layer, it blocks out everything outside the selected area, revealing the black background of the image.

To edit a Layer Mask, highlight the layer that contains the mask you want to edit in the Layers floating palette by clicking once on the layer. The mask will appear in the Channels palette and can be edited just like any other channel at this point; it will not appear in the Channels palette when the layer containing the mask is not highlighted. You can also edit the channel by clicking the thumbnail in the Layers palette. This will not show you the mask you are editing but will allow you to view the effects of the changes as you edit the mask. In either case, when the mask is active, the Layer Mask icon will appear to the left of layer in the Layers palette rather than the Paintbrush icon.

Layer Clipping Paths

A Layer Clipping Path is a resolution-independent means of applying a shaped clipping area to an image layer. The Clipping Path is applied with vectors rather than a pixel-based mask, so the result can be sharper in some instances. The difference between applying a Clipping Path and a Mask is similar to the difference between bitmapped and PostScript fonts. The limitation to a Layer Clipping Path is that the border is absolute; the path denotes a sharp break between inclusion and exclusion of image information. There is no means of blending as there is with a Layer Mask. However, Layer Masks and Layer Clipping Paths are not mutually exclusive: They can be used together and can, in fact, be made from the same selection.

To apply a Layer Clipping Path, you will need to create an active path. After the path is created, it can be applied to the layer in a way very similar to the application of a Layer Mask. Simply select Current Path from the Add Layer Clipping Path submenu on the Layers menu. This will create a Layer Clipping Path from the currently active path. Everything inside the area of the path will be revealed while everything outside the path will be clipped. Figure 3.8 shows the result of applying a Clipping Path to a layer.

Clipping Paths can be used in combination with Clipping Groups and Layer Masks in any configuration. When used in combination Layer Masks show up immediately to the right of the layer thumbnail, and Clipping Paths show up to the right of the Layer Mask. Clipping Paths, Layer Masks, and Clipping Groups can all use Layer Styles as well, which create effects based on the result of the masking(s). Figure 3.9 shows a combination of the previous examples used for Clipping Groups, Layer Masks, and Clipping Paths. You can try your hand at imitating these results in the "Photoshop at Work" section at the end of this chapter.

Figure 3.8
When a Path is active in an image, the outline will show. After the path is applied here, it blocks out the image area outside the path only in the layer it is applied to—unless that layer is the base of a Clipping Group.

Figure 3.9
The original image from these examples was of a somewhat red-faced Ben Franklin imitator. The red face and blue eyes seemed already to be waxing patriotic, and needed only a little further manipulation with the help of clipping and masking to look like a wacky patriot. Various clipping and masking effects are at work here to define the stripes and star.

Simple Blending Modes

Layers have several basic blending functions including Layer Modes, Layer Opacity, and Preserve settings. These settings can be used to control the intensity and type of interaction between layer information. All are found at the top of the Layers palette just above the stack.

A Layer Mode defines how the content of the layer will be applied to the elements in layers below. These Modes are pretty much the same as modes for application of painting tools, but the mode applies to the entire layer as an overlay. Layer Mode is most often used as Normal, but can be used in other modes both for special purposes and special effects.

Table 3.4 gives some details on the Layer Mode types. Rankings in the Frequency of Use column of Very Often, Often, Sometimes, Rarely, and Almost Never are based on photographic reproduction and application. For all applications, Layer opacity can be controlled by pressing a number key where 10 times the number is the opacity the layer will assume. Typing the exact opacity desired quickly will change the opacity to that number.

Table 3.4 Layer Mode Types, Effects, Uses, and Shortcuts

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Note - Also see images 5.51 to 5.66 in Chapter 5 for a simple black-and-white demonstration of how blending modes work.

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Layer Opacity determines the amount the current layer will obscure or affect the image information in layers below. An opacity of 100% means that the image information in the layer will interact completely with information below. A lower percentage means the effect and/or coverage will be less intense.

Settings for locking transparency and pixel content affect application of tools to the current layer depending on the opacity and content of each pixel in the layer. If neither is checked, images can be freely edited. If the transparency is locked, the layer will preserve current opacity for each pixel no matter what tool or effect is applied, but the content (color and tone) can change. If the pixel content is preserved (color, tone, and opacity), the layer will retain the information in the image essentially locking pixel values and disallowing any application of filters or tools that change content.

It is important to note that pixel information within the layer can be partially transparent, as it might have been applied to the layer with a tool that used partial opacity. In other words, if black was applied to a 50% opaque layer with 50% opacity, the result would be 25% opacity. Although you will probably most often use an opacity of 100%, you might find a number of reasons to reduce opacity in blending images and elements. This will affect the application of other tools if the layer transparency is locked.

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Note - Although there is no difference in the result in the image if applying a 50% opaque tool to a 50% opaque layer, applying a 100% opaque tool to a 25% opaque layer, or applying a 25% opaque tool to a 100% opaque layer, the result in the layer itself is different. The choice as to how to set opacities can be important and can be noticeable if duplicating the channels, applying additional changes via clipping groups.

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Layer Blending Options and Layer Styles

Layer Blending Options and Layer Styles are grouped effects for the layer controlled through the Layer Styles palette and dialog box. Layer Styles are really saved sets of Layer Blending Options. Selecting Blending Options from either the Layers palette pop-up or the Layer menu (under the Layer Styles submenu) will open the Layer Styles dialog box. The Layer Style dialog box is a one-stop management area for what were Layer Effects and blending modes (see Figure 3.10).

The Layer Styles dialog box actually allows you access to all the following and then some: Layer Styles, General Blending, Drop Shadow, Inner Shadow, Outer Glow, Inner Glow, Bevel & Emboss, Contour & Texture, Satin, Overlay and Stroke. I say "and then some" as there are numerous subeffects that can be applied using patterns, fills, gradients, curves, and so on. See Table 3.5 for a listing of the effects and the features each supports. These effects will be examined further in later chapters as the effects are applied.

Figure 3.10
To view the palettes/dialog boxes for each of the Effects, click the name of the effect. To apply the effect, click the check box. To shut the effect off, click the check box again so that the check is removed.

Table 3.5 Layer Style Effects

The preview box to the right on the Layer Styles palette allows you to view how the effects would look on a small square. The current effects can be saved for later use as Layer Styles by clicking the New button. This will allow you to choose a descriptive name for the new style and select options for what to save from the current style set. To recall the style you saved, all you have to do is open the Blending Options and select the style from the style menu. To view the saved Styles, click Layer Styles on the menu to the left. This will reveal all the Styles that are currently loaded. From this view, you can load more Styles and manage sets. You can also change the style views by selecting the desired view from the Layer Styles pop-up menu. See Figure 3.11.

Figure 3.11
Layer Styles can be viewed either with or without previews, with or without descriptions, and in varying thumbnail sizes. I find viewing the thumbnail and descriptions together helpful.

Adjustment and Fill Layers

Adjustment and Fill layers allow the user to apply Photoshop functions as layers. This provides an advantage in that the application of the function does not actually change the image information. The layer can be applied to the images later or discarded without stepping back in the History.

Fill and Adjustment layers are actually applied and managed through four separate menu items. Selecting New Fill Layer or New Adjustment Layer from the Layers menu adds a new layer to the image above the currently active layer. Upon selection, the New Layer dialog box will open to allow selection of the layer name, grouping (with previous), color code, mode, and opacity. When the New Layer dialog box is closed, the dialog box for the adjustment or fill function opens and the layer will be created. The layers are automatically assigned a mask and appear with an icon that is unique to the function selected. The mask can be turned into a layer clipping path by simply drawing a path or layer mask by using pixel-editing tools to change the channel information. A complete list of the icons appears in Figure 3.12.

Figure 3.12
The icons here represent the thumbnails that are created to identify the layer types.

After the layers are created, the layer content can be edited or changed. Change Layer Content enables you to change the function currently assigned to the layer. For example, if Levels are assigned to the layer and you would like to change it to Curves, select Curves from the Change Layer Content menu. To adjust the settings for the function currently assigned to the layer, choose Layer Content Options from the Layers menu, or double-click the function icon in the Layers palette. Either of those actions will open the dialog box for the function with the current settings.

The Blend If Layer Function

The Blend If function allows the user to create conditions in which image information will blend between layers. The sliders allow the user to target specific areas to blend from and to in consideration of color and tone. With measurements, application of color changes, repairs, and so on can be based on tonality.

This is useful for colorizing images, targeting tool application, blending back details lost in corrections, and a number of other applications. This might be infrequently used, but it is a powerful and exacting tool. Used in combination with new Layer options and in tune with the new interface for control of Layer Styles, this can more easily be targeted to your needs than in previous versions of Photoshop.