The spot and healing brush seems to work a little, but then leaves dark smudges or even complete dark lines. Also seems to pick up other objects in the picture as if it is copying a section of the picture. Have tried to reset, but nothing works.
The Spot Healing Brush in Photoshop CS5 uses Content Aware Fill, and it's function is EXACTLY to go find other parts of the picture to fill in over what you clicked on. What is it that you expect it to do if not that?
As Christoph has said, please provide some image examples. It may be that it's not working correctly, but it's impossible to tell whether you're seeing it do what's expected without seeing the before/after results you're seeing.
-Noel
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