Nondestructive editing is an overall strategy of working in Photoshop that allows you to backtrack your steps and, more importantly, edit without permanently changing image information. In short, nondestructive editing means that tools and tool options are used such that changes can always be undone. Photoshop provides many ways to work nondestructively.
Permanently altering or deleting pixels may result in having to rework an image because something important was removed or altered. Sometimes even the most insignificant spot in a picture may be important, which Wayne, long before he adopted a nondestructive philosophy, learned first-hand when having to redo work for a valuable client (FIGURE 5.3).
FIGURE 5.3 The white spots on the hand of baby were assumed to be part of the damage. In reality, they were reflections from family rings the child was wearing and an important aspect of the picture. By working nondestructively, removed items can be easily returned.
To work nondestructively, use:
Duplicate layers. Work on a copy of the Background layer when making edits, such as content-aware scaling, using the Dodge or Burn tools, or non-smart filters, that would otherwise be a destructive edit.
Adjustment layers. Keep tonal and color corrections separate from the background layer, permitting readjustments throughout the editing process.
Empty layers. Use painting, cloning, and healing tools that have the option to put edits on blank layers above the layer being edited.
Layer masks. Hide elements of a layer or parts of an adjustment layer through masking. Editing the mask later can reveal elements again if needed.
Smart Objects and Smart Filters. Convert a layer to a Smart Object before applying any filter, adjustment, or transformation so you can edit settings later without damaging the original image.
Some may argue that working with the History Brush tool and recording snapshots through various stages of work in the History panel allows for nondestructive editing. However, there is one critical caveat in that the contents of the History panel, which includes states, are not retained when the file is closed. This may not be a concern if you complete a restoration in one sitting and the file will never be revisited, but it becomes problematic if further changes or corrections are desired at a later time. History states can be saved as separate files, but there are more efficient methods for working nondestructively and managing your progress (FIGURE 5.4).
FIGURE 5.4 The History panel and snapshots keep track of steps taken when editing images, but they are lost when the file is closed.
The easiest form of nondestructive editing is simply duplicating the Background layer. Working with duplicate layers within the same document is a more efficient method to use when any of the Background layer information is going to be changed through filters or painting tools. Duplicate the layer and work on it, keeping the Background layer undisturbed. The Background layer can be used for progress reference by turning upper-layer visibility on and off, and sections of it can be copied and pasted over unsatisfactory edits. To duplicate the Background layer, choose Layer > Duplicate Layer, drag the Background layer to the New Layer icon in the Layers panel, or press Cmd-J/Ctrl-J (FIGURE 5.5).
FIGURE 5.5 The first step in nondestructive editing is to work on a duplicate of the Background layer.
Working on an Empty Layer
The Spot Healing Brush tool, the Healing Brush tool, the Clone Stamp tool, and even the Blur, Sharpen, and Smudge tools include the option Sample All Layers (or a variant, Current & Below or All Layers), which allows changes and repairs to be put on an empty layer above the Background layer. Since the changes are on a separate layer, they are easily refined by erasing or deleting the changes and trying again. Using this method, as opposed to duplicating the entire layer, also keeps the file size smaller because the layer with the changes is not the same amount of data as the Background layer. We all use empty layers all the time in both restoration and retouching work, and we’ll work through some useful examples in this chapter.
Working with Adobe Camera Raw
As explained in the following section, you can use Adobe Camera Raw (ACR) and, in a similar vein, Lightroom to clean up sensor dust and standard dust spots on film or print scans. The nondestructive beauty of ACR is that it never actually changes a file, and all changes can be reversed by opening the raw file in ACR or Lightroom again. Files processed in ACR can be opened in Photoshop as Smart Objects, keeping changes nondestructive.