[vtkusers] Sharpen Filter

[Luis Ibanez]

Hi Michael,

Assuming that you are doing this just for the purpose of providing
an image for visualization, as opposed to an image that is going
to undergo further processing...


You can build a quick sharpen filter by taking the original image
and subtracting from it its smoothed version.


>From the spectral point of view, this is equivalent to removing
low frequencies from the image, hence equivalent to enhancing
high spatial frequencies.

You may want to go a step further and multiply the smoothed
image by a constant to get some control on how much you
attenuate the low frequencies.

In pseudocode you end up with


  Sharpened image = Image - K . Smoothing( Image, Sigma )


    Typically K will be in the range [0,1].


and... you may want to go with a large Sigma, (e.g. spanning
more pixels than the details that you want to enhance).




   Regards,


        Luis


--------------------------------------------------------------------------------
On Tue, Jun 9, 2009 at 9:34 AM, Michael Knopke <Michael.Knopke at gmx.de>wrote:

>  Hi ,
>
>
>
> Thanks for the hint David, that’s what I want to do later (needs bridging
> between vtk-itk first).
>
> I just wanted to have some simple sharpen filter to apply onto the image
> (just like vtkImageGaussianSmooth but for sharpening).
>
> I know about vtkButterworthHighpass, but this is no option since it is
> terrible slow…
>
> Anybody else?
>
>
>
> Michael
>
>
>
>
>
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