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Non-Destructive Editing in Photoshop

April 15th, 2009

Zoltan Gyalog has come out with another nice tutorial article, this time focusing on a Photoshop technique called non-destructive editing, which is a way to modify images without making permanent, irreparable changes to them or “destroying” any of the pixels. Meanwhile, if you happen to be a Photoshop enthusiast, this same author has written another useful tutorial on colorizing black and white images in Photoshop.

Non-destructive editing is a workflow that focuses on leaving the source content of a project unmodified. The idea behind the concept is to create non-permanent edits. In other words: dynamic edits you could adjust later as need dictates. Ever since version number 3, Photoshop supports layers. The layer system is a key element of non-destructive edits. By default, the software handles all untouched images you open up as a Background reference. If you take a look at the Layers palette – hotkey: F7 – you will see that the project consists of the opened image and it is referred by Photoshop as the Background. A Background is not a layer though and layer-exclusive effects are not applicable on top of it.

Since the final result of a project is primarily dependent on the stacking order of the layers, it is a solid approach to build those on top of the Background reference. This way, the source content remains unmodified, while non-permanent editing changes can be introduced on each layer.

First of all though, let’s see how you can create and store different variants — including the original — of the source content via performing actions directly on the Background image. This technique makes use of Photoshop’s History feature. Open up the History palette by going to Window >> History on the upper menu bar. It could be a good idea to dock this palette to the Layers palette, creating easy, simultaneous access to both of those by relying on the same hotkey F7.

Every edit you perform in Photoshop is monitored and recorded. Go ahead and make the History palette active by clicking on its name in the Layers palette. If you introduce a change on the image now, like a stroke with a Brush, you will see that the software recognizes your action and adds a Brush Tool action event to the History palette. Repeat this process a couple of times and notice the consecutive Brush Tool events appearing in the palette. This is where the effectiveness of the History feature comes in. By clicking on any recorded action event you have performed, Photoshop will render the state of the image on which the chosen event occurred. You could travel back and forth between the changes you introduced.

What you really want to achieve though is a method to record a variant of the Background. Notice the tiny camera icon on the bottom of the History palette, left of the trashcan. By clicking this icon, Photoshop will create a snapshot of the current state of the document and will render it as a thumbnail image in a separate section of the palette that is specifically designed to store the snapshot variants. You could create, store, and evaluate an infinite number of these variants, each accessible by clicking on their corresponding thumbnail image.

However, there is one drawback — Photoshop does not save out snapshot information upon amending the changes. If you are happy with a variant, you need to create a new document based on the current state by clicking on the icon left of the camera. The document will be created and you could drag and drop it to the original document as a now-separate, individual layer, ready to be edited.

Non-destructive editing is not only about preserving the source content, it is also about creating a network of dynamic edits that you could activate or deactivate. In the following example, you will create a Text object and will assign different Layer Styles on top of it.

By default, all Photoshop layers are compatible with Layer Styles. These Layer Styles will give you fast and impressive results with fluent connectivity maintained between each other. Press the “t” hotkey to access the Text tool and enter a word of your choosing with fairly large fonts. You will see that a new Text layer is created in the Layers palette, marked by a big T.

If you double click on this layer, Photoshop will grant access to the Layer Styles submenu. Go ahead and select Stroke from the bottom. This effect will create a nice, crisp outline around the Text object. Notice that the parameters of the main window are changed: these dialogs are context-specific to the Stroke effect you just created. You can adjust the size, position, color etc. of the Stroke from here. Be sure that the little checkmark is activated in front of the effect’s name and click on the Drop Shadow option in the same submenu.

Notice that the parameters in the window are changed once again: these parameters are context-specific to the Drop Shadow Layer effect. Notice how the two different effects — Stroke and Drop Shadow — are stacked on each other, rendered simultaneously by the software. If you want to see them separately, you can deactivate the checkmark of the one you currently have no need for.

Layer Styles will remain stackable and flexible, though you could “burn in” all effects as final pixel data via a process called rasterization. Once you click OK and get back to the main editing window, you will see that the Text layer has an additional field to it, called “Effects”. Each effect you have created has a separate visibility toggle to itself, while double clicking on any of them will take you back to the corresponding parameters you amended.

The structure you created is entirely non-destructive, as you have permanent access to the original text object and to the effects that are reliant on the text. You could adjust the effects independently. No effort and no state of the document have been wasted.

Relying on stackable Layer Styles is a solid method to maintain non-destructivity on layer setups responsible for visual touches, while the pixel data you create using creative tools could be, and perhaps even should be drawn on separate layers. More complex Photoshop documents will consist of numerous layers as you progress along, and the time will come when comfort and clarity seduce you to merge particular layers down.

The merging of layers results in a single, new layer, created from the pixel data that was present on the separate layers before the merge. This seems to be a considerable risk factor, as there is no way of getting back to the previous layers once their pixels have been fused together. A solution that can overcome this problem is to make duplicates of the layers that you want to merge down. The next step, as you may have guessed, is to deactivate the visibility of these duplicates. Now you could merge layers down for the sake of comfort and manageability, though the unmodified originators of this new layer will remain accessible. Non-destructivity is maintained.

There are different methods to merge layers down. The most common technique is to use the “CTRL + e” hotkey combination on top of the layer that you intend to merge with the layer below. In case you want to merge numerous layers, first you need to specify the individual layers that you want to fuse. To accomplish this, mark the layers using “CTRL + left click”. Now rely on the hotkey combination “CTRL + e” to execute the merge command. There could be times when you are absolutely sure of what you are doing and intend to merge down all the layers to a flat image. To do so, you could go to Layer >> Flatten Image. Be aware that this command will burn all pixel data — including dynamic Layer Style effects — of the document to a flat Background reference.

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