[vtkusers] Sharpen Filter

[Luis Ibanez]

Hi Michael,

Yes,
adding the sharpened version of the image to
the original image is a common thing to do.


However, if you reconsider the expression:

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

and then the suggested addition:

  Final Image = Image + Sharpened Image

which is equivalent to:

  Final Image = Image * 2 - K . Smoothing( Image, Sigma )

You may agree with me in that the final image comes
down to a pixel-wise linear combination of the original
image and its smoothed version.

such as:

   Final Image = A . Image - B . Smoothing( Image, Sigma )

You can select the values of constants A and B to match
any normalization constrains that you may have on the
output image.


BTW:
   You could consider packaging this into a VTK filter
   and contributing it back to the community by submitting
   a technical report to the Insight Journal    :-)
   http://www.insight-journal.org/

   In that way other users will benefit from your efforts.



   Regards,


         Luis



------------------------------------------------------------------------
On Wed, Jun 10, 2009 at 5:28 AM, Michael Knopke <Michael.Knopke at gmx.de>wrote:

>  Thanks a lot Luis for that hint!
> After checking some books about filters it’s kind of obvious to me now …
>
> Just one more question to your approach:
> After removing the smoothed version from the original image I probably need
> to add the result to the original image again (which enhances edges only),
> at least this is what the books suggest or is there another way? If I don’t
> add it, I get only an edge image…
>
> Regards,
> Michael
>
>
>
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