Bob briefly listed 3 things to avoid if you want to keep you images from unnecessarily losing overall sharpness during post-processing.
- Anything done in Photoshop’s Edit/Transform will change pixels in the image. When rotating an image (e.g. to straighten the horizon in a landscape picture) keep your adjustments to a minimum number. Do not rotate and hit ‘return’ several times. When you find the right position, push ‘undo’ to cancel the previous rotation, if you made one, and make one adjustment to reach the correct position.
- When using the lens correction feature to correct for shape or other difficulties introduced by your particular lens, keep adjustments to a minimum. Try to find the best set of adjustments, hit ‘reset’, and apply those adjustments once only.
- Be aware that when resizing an image, if you select ‘resample’ you will degrade the sharpness of your image somewhat. Take care in using that option.
Note that when using Lightroom in ‘Develop’ mode it does not matter when you apply sharpening in terms of your workflow, but in Photoshop you should try to apply sharpening near the very end of your workflow to avoid affecting pixels adversely. Also it is often recommended that the preferred sharpening filter is ‘Smart Sharpen’ rather than ‘Unsharp Mask’, and the type of blur chosen is ‘lens blur’ rather than ‘gaussian’. There is room for personal choice here. The differences may be very subtle.