Quick Guide to Using Photoshop Layers for Great Nighttime Shots
- Creative functions are found in every nook and cranny of Photoshop, yet few are as significant as the layer and selection features. These tools—used both separately and in tandem—allow you to stretch the boundaries of your photographic vision by manipulating images in a dizzying variety of ways. Just about every task performed in Photoshop uses one or both of these functions.
Selection and Layers
SELECTION AND LAYERS are essential to nighttime photography and producing many projects discussed in this book. This chapter covers various methods for isolating picture components from a single image and constructing the various pieces into a whole image. Layers act as individual sheets where a series of picture elements can be combined into a single image. Selection refers to isolating a portion of an image for use as a picture element in a layered image, or to separate an area of the photograph to make an adjustment. Any changes you make to tone, color, or effect are confined to the area of selection.
The ability to separate selective elements and reconstruct them as a single image allows for greater flexibility and possibilities for representation. Each picture can be tailored to your personal vision. Multiple-layered images are not only used for creative purposes but also come in handy for various practical measures, including tonal adjustments, Smart Objects, and special effects.
Creating image adjustments, as well as constructing a composite image, depends heavily on how successfully the parts are isolated from the rest of the image. Photoshop offers multiple ways to make a selection, each with specific qualities that depend upon personal preference. Most are found on the toolbox palette, though a few are accessible through the main menu.
The Lasso tool creates a selection when you hold the mouse button and draw around the area. When the mouse is released, a selection border surrounds the area (FIGURE 4.1). The Lasso provides three variations (FIGURE 4.2). The most common lets you draw freehand selections completely around the area. If you do not close the selection by drawing back to the place where you started, the tool will do it for you, choosing the shortest distance between the two points. The Polygonal Lasso lets you draw straight line segments that you connect back to the starting point. It is a great function for drawing areas with straight edges or drawing geometric shapes. Perhaps the most interesting choice is the Magnetic Lasso tool, which lets you draw a freehand line around an area of the image—while automatically adhering to the dominant edge—making for a clean selection. This feature is especially useful when it comes to complex edges set against high-contrast backgrounds.
Figure 4.1 The hat was selected on this statue of George M. Cohan using the Lasso tool.
Figure 4.2 Lasso tool options: Normal, Polygonol, Magnetic.
Found on the toolbox palette, the Quick Selection tool lets you make fast, accurate selections of irregularly shaped objects without having to manually trace over them (FIGURE 4.3). You select them by dragging its brush across the desired areas of the image. Selected areas are based on color and tone. As you continue to brush, you can add to the selection by staying within the edges of the desired area. Don't worry if you go outside the area; you can easily undo it by changing the tool option to Subtract From Selection in the Menu Options bar, and dragging inside the area (FIGURE 4.4). You can choose a brush size there, too, or take the keyboard shortcut by using the bracket keys to expand or decrease brush size.
Figure 4.3 The Quick Selection tool shares a spot in the toolbox with the Magic Wand.
Figure 4.4 The Quick Selection tool differentiates the edges of the similar warm tones in this Halloween decoration. Dragging it downward selects uniform areas of tones.
This feature selects similar colors on the image without having to trace an outline around an object. Simply click on an area to begin your selection. The sensitivity of the selection depends on the tolerance and the selection option. When the tolerance setting is low, the tool selects similar colors, while higher values produce a wider range. The Magic Wand works best for areas that show a clear color difference between the main subject and background. Images with a wide range of density can show more marching ants than a candy bar left overnight on the sidewalk.
This new feature lets you fine-tune your selection by providing a variety of options to fix the edges and show how the selection appears against different backgrounds. It works with all of the selection tools, so instead of having to choose individual effects—like Feather, Expand Selection, or Smooth—it includes them in the same palette (FIGURE 4.5). In addition, it provides a preview of these effects. Refine Edge is accessible through a button found on the Options bar of all of the selection tools, or at Select > Refine Edge.
Figure 4.5 The Refine Edge tool.
Refine Edge offers the following controls:
- Radius: Smooths the edge areas with soft transitions.
- Contrast: Makes the soft edges of a selection appear crisper.
- Smooth: Removes jagged edges from a selection.
- Feather: Softens edges with varying degrees of blur.
- Contract/Expand: Increases or decreases the area of selection.
Figure 4.6 The blue sky in this Chicago nightscape was selected using the Magic Wand tool. In the Standard Selection mode, the marching ants that define the selection surround the area.
Figure 4.7 Quick Mask previews the selection with a color overlay.
Figure 4.8 On Black previews the selection over a black background.
Figure 4.9 On White previews the selection over a white background.
Figure 4.10 Mask previews the mask that defines the selection.
This tool allows you to make a square, circular, or linear selection (depending on the tool) by clicking the mouse button and dragging the box, circle, or line in the desired area. It's useful to start a complex selection with the Marquee tool and fine-tune it with the Lasso. This tool offers several variations, including the Elliptical Marquee to make ellipses or—when holding down the Shift key—concentric selections; and the Single Column, Single Row Marquee for defining a one-pixel-wide row or column, respectively (FIGURE 4.11).
Figure 4.11 Marquee tool options are Rectangular, Elliptical, Single Column, and Single Row.
The Marquee, Magic Wand, and Lasso tools provide options for building your selection. They allow you to create a new selection, add to an existing one, subtract from the selection, and intersect with another selection (FIGURE 4.12). New begins a selection, Add To builds on a selected area; Subtract From removes overlapping areas; and Intersect With restricts the selection to the area it's dragged over. Whenever you create a new selection, the Add To selection function is automatically activated; the others are accessed manually.
Figure 4.12 Selection options are New, Add To, Subtract From, and Intersect With.
You can also add to the selection by holding down the Shift key and dragging it to extend the area (a small plus sign will appear). Hold down the Option key (a small minus sign will appear) to reduce the size of a selected area.
Up until now, selection options depended on drawing lines—either freehand or automatically—around a portion of the image. The Quick Mask takes a different approach by allowing you to paint a temporary mask with the brush type and size of your choice. You can create the mask entirely in the Mask mode or convert a previous selection. To activate the Quick Mask mode, select its toolbox icon.
The masking color, similar to the antiquated ruby lith overlay that was used in the prepress process, covers the selected area. Click on the Brush tool, and begin painting your selection (FIGURE 4.13). By default, the color overlay protects the area outside the selection. When you're finished, click back on the standard mode button, and the painted area is transformed to a selection, replete with marching ants (FIGURE 4.14). This method works for situations that require intricate selections. To erase a mask area, click on the switch colors arrow on the toolbar to transform the brush.
Figure 4.13 This Lego sculpture was painted with the Quick mask.
Figure 4.14 After toggling back to the standard mode, the masked area now has a selection border.
You can change to indicate the selected area by changing the Quick Mask options. Just double-click on the Quick Mask icon and a dialog will pop up. Change the radio button to Selected Areas. You can also change the mask color and its opacity (FIGURE 4.15).
Figure 4.15 Quick Mask options.
The mask can also be converted to an alpha channel. Whenever you choose this mode, it automatically creates a temporary Quick Mask in the color channels palette. That can later be converted to an alpha channel by switching to the standard mode and choosing Select > Save Selection.
For a different approach to selection, try the Color Range function. It's found on the main menu at Select > Color Range, and it works like the Magic Wand tool on steroids without the excess marching ants. This command bases selection on a specified color or color subset, making it best for separating a single color throughout the image (FIGURE 4.16).
Figure 4.16 A night baseball game.
After opening the dialog, you'll see a small black-and-white version of the picture (in Selection mode, Image mode shows the picture in color). When you click on a color in the image, the image tones will change. White areas reveal selected pixels, while black areas show unselected parts (FIGURE 4.17). Partially selected areas show up as gray. Once satisfied, click OK and the marching ants will return to show the selection (FIGURE 4.18).
Figure 4.17 In the Color Range palette, the green field was selected with the dropper.
Figure 4.18 After hitting OK, the selection border surrounds all of the green areas in the image.
Working With Selections
Use the Magnification tool to increase the size of the screen image. This makes it easier to see what you are doing and apply a more precise selection.
For maximum examination, choose Window > Documents > New Window to add another document window on the desktop. By keeping one at full view while working on the other at a higher magnification, you'll be able to make precise adjustments while observing their effects.
The selection border identifies each selection. While it's helpful to see the chosen area, sometimes it's hard to differentiate it from adjacent ones. To hide these marching ants, go to View > Extras. The keyboard shortcut is Apple-H on the Mac and Control-H in Windows. The Extras command covers many nonprinting functions in Photoshop including, grids, guides, and image maps, depending on what is active at the time.
If you are not satisfied with the selection, or are finished with it, deselect the area by going to Select > Deselect, or use the keyboard shortcut Apple-D on the Mac and Control-D in Windows.
Select > Inverse lets you switch the selection order. This comes in handy when selecting a dark sky, then inverting to the subject against it.
Composite pictures—those made from two or more images—are constructed on separate layers, allowing you to manipulate, reposition, or delete an element residing on one layer without affecting the others. The Layers mode transforms Photoshop into a tablet of virtual acetate where individual picture sections are stacked as a single image. The order of the layers affects image composition, since the element on top covers the layer beneath it.
Whenever you open a file in Photoshop, that image becomes the background, with successive layers added above it. The background layer cannot be moved; however, you can convert it to a regular layer to move its position. Double-click on the layer, and name it when prompted.
At this point, the bottom image becomes the background by default, but it is not a true background because it's not constrained. To permanently convert any layer to a background, go to Layer > New > Background Layer.
By default, the Layers palette is positioned on the right side of the screen, or found at Windows > Layers. To create a new layer, or perform various other layer functions, see FIGURE 4.19 for location and a brief description of each feature on the Layers palette.
Figure 4.19 The Layers palette
Working With Layers
The transparent quality and effect of each layer can be adjusted. Just as a piece of acetate on top of the image covers the images below it, this mode changes the way that each layer combines with the underlying layers. The order of each layer can be dragged above or below for adjustment.
Turn off the visibility of each layer by clicking the eye icon. This allows you to isolate a particular element to make a precise adjustment. Click the empty eye column to display it again.
Both PSD and TIFF support saving files with multiple layers. Other formats will save the file as a flattened image.
Double-clicking the layer reveals the Layer Style palette, which offers control over effects and blending.
Group two or more layers together if you want to move their contents as a single object. Simply click on the column next to the desired layers you need to move, and a chain link will appear.
If you plan to create multiple versions of a single image, you can create a layer set to organize the picture elements for each one. This comes in handy when you're working with dozens of layers.
To display a layer while hiding the others on the Mac, Option-click the eye column next to the chosen layer in the Layers palette. In Windows, Alt-click. To redisplay the hidden layers, use the same command.
Once components are arranged, you can merge your layers. This makes it easy to manage multilayered image files, and you are less likely to inadvertently change the order.