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Camera Sharpening Experiment

Discussion in 'Olympus Cameras' started by Brian Beezley, Nov 24, 2013.

  1. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    [​IMG]

    I am a beginner at photography and I need all the help I can get. I shoot RAW so that I have a better chance of correcting my mistakes after I take a photo. I use an E-PL2. While the Olympus manual does a pretty good job of elaborating the various features, it seldom offers much explanation. This is true for camera sharpening. My E-PL2 lets you set Sharpness from -2 to +2 with a default of 0, but the manual offers no guidance for setting this parameter.

    To avoid artifact propagation, I decided that I wanted to do all sharpening after all other image processing and at the output resolution. To do this I need to disable any sharpening in the camera. I thought it unlikely that the camera would actually blur an image so I figured -2 was no sharpening, or perhaps a minimal amount. A couple days ago I sent a question to Olympus asking whether this guess was correct. While waiting for an answer, I decided to try an experiment.

    The image above is a composite of 100% crops. In one, camera sharpening is -2, and in the other it is 0. I used Olympus Viewer 3 to set the two values for the RAW image. While 0 is noticeably sharper than -2, some sharpening halos are visible, particularly surrounding the vertical cables. So I think my guess is correct. I'll update this post after I hear back from Olympus

    Brian

    P.S. - Olympus confirms that setting Sharpness to -1 or -2 does not blur the image. Instead, it lessens the sharpening amount. They also say that there is no way to completely eliminate sharpening with Olympus Viewer 3.
     
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  2. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    [​IMG]

    I thought I noticed a barely perceptible sharpening halo surrounding the vertical cables even for Sharpness -2. The image above is a 100% crop of a cable magnified 500% with no pixel interpolation using IrfanView (16-bit uncompressed TIFF source images). The left image is from Olympus Viewer 3 with Sharpness set to -2. The right image is from RawTherapee using Amaze demosaicing and no sharpening.

    [​IMG]

    This shows intensity along a horizontal line across the center of the image. The little bumps adjacent to the left dip are sharpening halos.

    Brian
     
  3. b_rubenstein

    b_rubenstein Mu-43 All-Pro

    Mar 20, 2012
    Melbourne, FL
    Olympus Viewer 3 is a very "blunt" tool in general and even worse for sharpening. I find it primarily useful for checking to see what camera settings were used, because it can make sens of all the EXIF data. Here's the thing about sharpening artifacts, and all other nit-noid IQ items for that matter: it all depends on how the image is being used. If you blow files up 500%, you'll see all sorts of ugly stuff. If you made a 12 x16 print with sharpening set to +2, you'd never see the halos.
     
  4. Ross the fiddler

    Ross the fiddler Mu-43 Hall of Famer

    You say you shoot RAW? The sharpening only sharpens the jpeg but will also be embedded in the EXIF data of the RAW file & will show in converters that read those settings when opening RAW, such as Oly Viewer 3 would do, however that can be changed in the RAW Editor anyhow just like WB, Noise Filter etc..