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Post sharpening on shallow DOF shot?

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    in Premiere, "sharpen" is convolution sharpening (jcs dixit)

    and also: this is what wikipedia has to say about USM vs deconvolution:
    Last edited by Samuel H; 05-12-2012, 02:28 AM.


      In PPro, convolution sharpen is: Effects/Video Effects/Blur & Sharpen/Sharpen (GPU accelerated). Unsharp Mask is below it.

      Convolution Sharpen works by starting with a center pixel, and sampling surrounding pixels in a square (typically forming a 3x3 grid). 9 pixels are sampled and multiplied by positive and negative numbers ("weights") in a matrix corresponding to pixels, and the resulting values are added up for the final value. This is done 3 times, once for R, G, and B (or Y, U, and V, depending on implementation). It won't form halos, even at high amounts, but will show artifacts and aliasing at high amounts.

      Unsharp Masking (USM) works completely differently. USM first creates a blurred copy of a region of pixels, then subtracts the blurred pixels from the original pixels (and rescales them so brightness is not affected). With a radius of < 1, it looks similar to Convolution Sharpen. With a radius of >=1, it can form halos (as in-camera sharpening does on the 5D3). With a really large radius (50-100+), it can be used to perform Local Contrast Enhancement. While USM could easily be GPU accelerated, it's not in PPro (including CS6). Too bad PPro can't run custom pixel shaders as can AE. This would allow many custom, real-time GPU accelerated effects to be performed in PPro that aren't built in.

      Deconvolution is different from Convolution: it's much more complicated and tries to model all stages of the source blurring process. If the blurring process can be accurately modeled, the total blur can be reversed, and the original, sharp image can be reasonably recovered. Deconvolution is very difficult to do correctly, and is used mostly for astronomy and microscope applications. Canon's post tool which recovers edge sharpness, etc., is a form of deconvolution. They can probably do a pretty good job as they have a good idea what the lenses are doing and the entire light path.


        It's possible to create USM in PPro which is GPU accelerated:

        1. Create a copy of the clip and stack above the original.
        2. Apply a Gaussian Blur to original. Set to 10 to start.
        3. On the upper clip, apply a Brightness & Contrast and set Brightness to 63.7 and Contrast to 50. Set Blend Mode to Difference.

        Adjust Gaussian Blur on original to control radius, adjust Opacity on the top video to control amount. It's not quite the same as the built-in USM, however it shows how it's done and that Adobe could include a GPU accelerated version instead of the slow CPU version.

        Also try adding an Adjustment Layer (CS6) or Nesting (CS5.x), and applying a (convolution) Sharpen to the Layer or Nested clip.

        Tested this technique in CS6 with a 1280x720@60 clip and it brings detail up significantly (and runs in real-time).

        Haven't looked at it in depth, but 1280x720@60 ALL-I looks more detailed than IPB in CS6 (don't see that difference between ALL-I and IPB at 1080@24).
        Last edited by jcs; 05-12-2012, 03:26 PM.


          JCS - Can you use a base 5DMKIII still as an example and show the different methods of sharpening? Probably a lot of work, but I'm interested.
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          Allow me: fanboy of great images.


            Looking forward to the sharpen feature of the upcoming Dark Energy plugin


              Originally posted by Kholi View Post
              JCS - Can you use a base 5DMKIII still as an example and show the different methods of sharpening? Probably a lot of work, but I'm interested.
              720p ALL-I from camera:

              720p with the above 'manual' USM, followed by Sharpen, followed by custom GPU noise grain (runs real-time):

              Sharpening was applied to the 720p video scaled up to 1080p and slowed down 40% (60-24fps). Looks better in motion- can't really tell it was 720p source when watched full screen (including on an HDTV).


                nice! (too much grain for my taste, but nice!)


                  Wow, the sharpening actually looks kind of crazy on the background. On your face it looks decent, maybe a bit too much sharpening, but the blur on the background makes it lose the nice soft feel because of all the noise. Now it feels rough and too noisy.
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                    Everyone has their prefs; again, looks very good in motion at 1080p (720p original). As a still, I like the original better, however in motion the processed version is much better. Being able to make the soft 5D3 720p look detailed at 1080p (for slomo) is pretty cool.

                    Kholi asked for an example; you can try these methods yourself and sharpen+grain to taste.