Working non-destructively in Photoshop

Have you ever been working on an image in Photoshop and needed to go back to an earlier version? Maybe a photo was sized too small or a filter was applied with too much intensity. After a while you changed your mind, or maybe the client wants something different after the job was supposedly finished. Especially in professional work, the more flexibility you have with your image editing, the better off you are.
Many of the tools Photoshop offers edit pixels in a destructive manner. That is, they permanently change pixels. Image adjustments, transforming, filters, erasers, brushes, and more usually work this way. Destructive editing is like killing pixels: once they are dead, that’s it. Sure, you can undo or go back in the History, but this is very limiting. The more non-destructively you work, the more options are open to you. In the past, we had to duplicate layers before making a change to have access to the original content. Photoshop now offers four better methods to do this: pixel layers, adjustment layers, masking, and smart objects.
Layers are pretty obvious. Believe it or not, back when I first learned Photoshop in school, it didn’t have layers at all. Everything had to be done with active selections and Alpha channels. You may know that you should paint on new layers, but did you know you can also use cloning and healing tools on blank layers? Just be sure to check their options to sample Current & Below or All Layers and get to work non-destructively covering up the stuff you don’t want.
Masking is another way to work non-destructively that has been in Photoshop for a long time. To remove a background or other unwanted areas, make a selection, then instead of deleting or copying and pasting, add a layer mask. The unwanted content is gone, but still there. You can paint white on the mask to bring it back. The new Properties panel in CS6 allows you to feather the mask edge, reduce its density, and refine its edge. None of this is possible if you erase or delete. You may never need to use an eraser tool again. Photoshop offers pixel-based layer masks, vector masks, and clipping masks. You can even group layers and add masks to the entire group. The possibilities are endless!
Most image adjustments should be done with adjustment layers. They don’t add much to the file size and can be edited over and over. If you have a selection active beforehand, the adjustment layer gets a mask automatically. They can be clipped to only affect one layer and you can even change their opacity and blend modes.
The newest and most powerful way to work non-destructively is with Smart Objects. Back when they were first introduced, they were pretty cool, but by CS4, they got even smarter. Like any other layer, you can mask them and change opacity, fill, and blend mode. But what is really great is how they protect the content on a layer. Any changes you make only affect the Smart Object, not the content. Now filters are smart. You can re-edit them, add multiple filters, change their order, and mask their effects. Transforming is also better. You have the full range of scaling, rotating, skewing, warping, and the rest. You can apply a transformation, then go back and do some more. All the values from the last time will still be there; they don’t reset. So, before doing any image editing, try converting each layer to a Smart Object as a first step. This works for more than raster content. Smart Objects can hold multiple layers, vector shapes, type, 3D objects, and even other smart objects. Just double-click the layer thumbnail to access the original, untouched content. And remember, don’t kill pixels if you don’t have to.

See full post here: Digital Illustration with Adobe Photoshop CS6 Extended2013-01-07.