IMHO, the word "destructive" is misused in PS. *All* tools in PS will make some changes to the pixels in an image. Some tools, because of their inherent blunt algorithms and/or their lack of precise user controls (think anyone with a hacksaw), can make more dramatic or less desirable changes to degrade the quality of an image. But even tools with good algorithms and controls can be abused by users (think Paris Hilton with a table saw). When images degrade in quality due to pixel information being mishandled, that to me, is destructive. This can be done with or without adjustment layers.

But typically, that's not how the word "destructive" is used. People use the word to mean an edit that cannot be undone. In that sense, edits done with an adjustment layer is "non-destructive" since these edits can be undone or altered.

Back to the original question about shadow/highlight. The s/h tool is not available as an adjustment layer option. Edits with s/h cannot be undone or altered and some may call it "destructive" in that context. But the s/h tool's algorithm can make dramatic and undesirable changes to degrade an image's quality if not applied with care. In particular, it can clip and lose details in shadow and highlight, and the tool has no good control to prevent these losses.

"Johan W. Elzenga" wrote:

eddie wrote:

If I may add to this and ask a question to Johan,as I am enjoying learning Photoshop,using version 8
Why is an adjustments layer less destructive than working on something like a background copy layer?

It's not less destructive than working on a copy layer, it's less destructive than working directly on the only layer. If you work with layers, the original image (underlying background layer) is untouched. The only difference is file size: An adjustment layer doesn't add much to the file size, unless you add an extensive mask (or work in 16 bits). A background copy layer doubles the file size, even without any mask.
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Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/

lewisfd

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shadow/highlights