Because the unsharp mask subtracts a smoothed version of the original image, it should also tend to remove background gradients.
> Hi
>
> there is no principal difference, both will in the end enhance higher
> spatial frequencies relative to low spatial frequencies,
> however sharpening kernels enhance higher spatial frequencies by evaluating
> differences between adajacent pixels and
> adding a weighted sum to the central pixel, while the unsharp mask first
> goes the other way round, it creates an even
> less sharp version of the image and calculates a weighted difference to the
> original image.
>
> Depending on the weighting parameters, resp. the sharpening or smoothing
> kernels used, the different methods will exhibit
> different tradeoffs between edge steepness, overshoot etc and noise on the
> other hand, that´s the reason the different
> methods exist.
>
> Hope this helps
>
> JW
>
>
>
>
> Klughammer GmbH
> <opto@KLUGHAMMER An:
[hidden email]
> .DE> Kopie: (Blindkopie: Joachim
> Wesner/DEWET/LMSCentral/Leica)
> Gesendet von: Thema: Sharpen Filter
> ImageJ Interest
> Group
> <
[hidden email]
> .GOV>
>
>
> 18.07.2006 18:59
> Bitte antworten
> an ImageJ
> Interest Group
>
>
>
>
>
> Hi,
> can anybody explain the difference of the sharpen filter and the unsharp
> mask.
>
> Anneliese
>
>
>
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