It may be easiest to think about the power of Smart Objects in comparison to the way many Photoshop tools typically work. The Puppet Warp tool, for instance, allows a photographer to rotate, resize and distort pixels on a layer, but when the edit is completed, the pixels are rasterized in their new location. There’s no undoing the change or further fine-tuning it, short of undoing the warp and trying again. But with a Smart Object, each edit is saved in the layers palette adjacent to the Smart Object, and long down the road, the photographer can double-click the edit in the layers palette to reopen the corresponding dialogue and make adjustments as if they had been performed when the edit was initially made. In this way, a Smart Object is kind of like an unlimited undo function that applies to actions that otherwise can’t be modified.
In practice, using a Smart Object is fairly straightforward. Right-clicking on a layer in the layers palette brings up a menu that includes the option to Convert To Smart Object. After a moment of processing, the Smart Object is now represented in the layers palette by a modified icon. Subsequent filters and edits to the object are represented by Smart Filters stacked below the object in the layers palette. A Gaussian blur, for instance, modifies the actual pixels on a layer. But performed on a Smart Object, the amount of blur is never set in stone. It can be changed later in the editing process simply by double-clicking on the Gaussian Blur Smart Filter found below the Smart Object on the layers palette.
Another unique aspect of Smart Objects is their ability to link a single image element between multiple files. Make edits to one element via a Smart Object and it will update across the other files that reference it. This is especially useful for designers, but commercial photographers may find it useful too, particularly for repetitive, quantity work.
Perhaps the thing that makes Smart Objects so incredibly versatile is their ability to be easily edited as standalone images. To do so, simply double-click on the layer icon of a Smart Object in the layers palette and it will open in a new document in Photoshop. From there, edits can be made—from painting to transforming or any Photoshop adjustment a photographer cares to make—and after saving and closing the file, those edits are visibly rendered to the Smart Object in the original file.
Any image can be opened as a Smart Object by choosing Open as Smart Object from Photoshop’s File menu. Alternatively, choosing Place Embedded from the File menu will add an image file to an already-open image as a Smart Object. To convert an existing layer to a Smart Object, simply right-click it in the layers palette and choose Convert to Smart Object. It’s good practice to convert layers this way to preserve the option of nondestructive editing, even if the photographer isn’t sure how they’ll be using them.
No matter how you create a Smart Object, their versatility makes them especially useful for photographers who want maximum control and the never-ending ability to fine-tune their image edits.