Dear all, when u go to filter->unsharp mask, a window will pop up showing a seemingly magnified view of some part of the picture, and then u willbe able to input radius, etc, and when u click the preview, u will be able to see the effect of the sharpening. Right ? My problem is sometimes, that little window does NOT show anything ( just blank ! ), and the unsharp mask does not seem to have any effect at all, inspite of how I slide the values around ? I cannot understand why sometimes it works and sometimes it doesn't. Can someone pls help ? Thank you.