Photoshop Tip: Lessen the effects of in-camera sharpening
Tips & Tutorials, by Mark White
November 28, 2012
Most digital cameras apply sharpening inside the camera (unless you use RAW mode), but often this can be too much
To remove over-sharpened edges, duplicate the Background layer by pressing Cmd/Ctrl+J and add a small amount of Gaussian Blur (Filter>Blur).
About 0.6px is all that’s needed to reduce the sharpened image. Reduce the opacity of the layer if required to blend better with the original.