5 Replies Latest reply on Sep 19, 2008 9:04 AM by (LUIS_A_GUEVARA)

    De-convolution sharpening

    Dennis 1111 Level 2
      I decided to start this topic to respond to a comment by Jeff Schewe in another thread. I would have just replied there but since the other thread was more about up-rezzing, my comment there would have been slightly off-topic. This also gives me the opportunity to make some recommendations to Jeff and the ACR team that have been on my mind for a while.

      Anyway, the comment from Jeff that caught my attention in the other thread was related to deconvolution sharpening and he said:

      >> It's designed not for "general sharpening" but to undo certain kinds of blur...

      I would have to disagree with you on this one, Jeff. I have found deconvolution sharpeners to work very well for stage 1 sharpening and I would recommend that Adobe give a deconvolution method a serious consideration for including in ACR in the future.

      I originally considered these tools "gimmicks" (tools to make a horrible pic less horrible) but began seeing comments from several posters over on the Luminous Landscape and Fred Miranda forums about how they used these tools for Stage 1 sharpening. I was skeptical but decided to see what they were talking about. I tried both Focus Fixer and Focus Magic and I was extremely impressed.

      The advantages I have found with these tools are:
      - Virtually no halos
      - Very effective at eliminating anti-alias blur (and on a good day, some lens softening as well) - exactly what you are trying to do at Stage 1.
      - Very easy to "tune". You can see very easily when you "go too far".

      I think the biggest barrier to these types of tools in the past was their load on the CPU but this is much less a problem today than a few years ago.

      As I mentioned at the beginning, I recommend that Adobe give this technology a consideration for future versions of ACR and Lightroom. For Jeff, if you ever decide to continue Bruce Fraser's excellent work on sharpening, I strongly recommend you add deconvolution sharpening to the list of topics. I think it is time for you to give it a second look.
        • 1. Re: De-convolution sharpening
          Level 1
          > I think it is time for you to give it a second look.

          I've looked at deconvolution sharpening...and it really only works really well when you can determine the precise point spread function (PSF). Smart Sharpen has the ability to do deconvolution sharpening but with only a single iteration.

          Deconvolution correction was originally designed to correct for astral drift on long range telescopes where it's relatively easy to mathematically determine the PSF. It's much more difficult to determine the PSF for camera shake or subject movement with subject movement a bit easier to correct for than camera shake where movement may not be a single direction.
          • 2. Re: De-convolution sharpening
            Mathias Vejerslev Level 2

            Contrary to removing camera shake blur (which none of us are discussing here), determining the PSF just for removing anti-alias blur is not very complicated or complex, as Smart Sharpen Lens Blur testifies. I wouldnt mind seeing Lens Blur deconvolution sharpening ´(including tonerange limiters) within ACR.
            • 3. Re: De-convolution sharpening
              PECourtejoie Adobe Community Professional
              >"...their load on the CPU..."

              I wondered the other day if GPUs are proficient for this sort of calculations...
              • 4. Re: De-convolution sharpening
                Mathias Vejerslev Level 2
                Hi Pierre,

                I guess you could load lots of stuff onto GPUs (I don't know the specifics of what exactly). But already I never, ever, see my quad processor max out in Photoshop. Max I've seen has been around 80% developing (saving) several photos in ACR.
                • 5. Re: De-convolution sharpening
                  Not that I am proficient at it , but the ability to perform Fourier Transforms, Convolutions, Deconvolutions etc, already exist in Photoshop CS3 Extended ,as a connection to MatLab.

                  There is a folder inside the Photoshop Extended , Installation folder, that allows you to create a Photoshop Toolbox in MATLAB. This toolbox creates an easy to use workflow for scientist and researchers using MATLAB and Photoshop in combination. This is a set of MATLAB "m" files that expand MATLAB functions and allow MATLAB users to call Photoshop commands directly from the MATLAB command prompt. This enables the ability to get and set pixel values directly in MATLAB and then view the resulting image in either one.

                  For more info:
                  http://livedocs.adobe.com/en_US/Photoshop/10.0/help.html?content=WS298C49A0-AC53-43c5-B19D -554CE1D87C3E.html