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Sharpness reduction from rotation in crop and vertical in transform.

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11 comments

  • Rick Sammartino Community moderator

    Which photo is which? Looking at both examples I like the one on the left more as it's more natural looking. The right photos look over-sharpened. I think you have other processing going on here making it hard to judge.

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  • Angus MacDonald

    Hi Rick,

    Thanks for the input. Appreciate your taking the time to comment.

    The one on the left is the rotated one. Both have the exact same amount of sharpening applied.

    The sharpening is to 50 in the detail slider, which applies Progressive sharpening. I have found that amount to be to my liking except when it appears diminished with rotation. It seems that one needs to do the crop, rotate and then sharpen.

    I have a Preset applied to all my photos with the above applied. Perhaps one needs to adjust each photo individually.

    Again, thanks for your help.

    Best, Angus

     

     

     

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  • Angus MacDonald

    Or, perhaps I need to change my Preset to reduce the sharpening to say 25 or thereabouts.

    I'm going to alter this now; I agree it does look somewhat overcooked.

    However, my original question pertains.

    Why does rotation and indeed, transformation. seem to reduce sharpness?

    I have submitted this query to ON1 and am anticipating a reply soon.

    I suspect any change to the original photo, wherein re-orientation is involved, will have this reduction effect as the software cannot reinvent the wheel so to speak!

    What say you all?

    Best, Gus

     

     

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  • Brian Lawson Community moderator

    Are you applying the sharpening with a Sharpening Effect or via the Details panel? If you are adding an effect it should definitely come after the rotation. That type of sharpening should always come last as all the other editing will have an affect on, sometimes reducing it while others can exaggerate it.

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  • Angus MacDonald

    Hi Brian,

    Thanks so much for your helpful input. I have been, somewhat lazily, applying the 50 sharpening in the Details Panel as a Preset. I have noticed that it is not consistent...sometimes it even looks overdone when I then Crop.

    Might you suggest the better approach is to simply not use a Preset at all, and simply edit each photo individually? Hmmm, back to Basics?

    Thanks so much for your help.

    Best, Gus

     

     

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  • Brian Lawson Community moderator

    The sharpening done there takes place at a different point in the processing pipeline. There are 3 kids of sharpening.

    1. Pre-sharpening which happens before any other processing and is basically to correct for the inherent loss in sharpness from the sensor. This is the Details panel's job.
    2. Local sharpening for directing the viewer's attention. Sharpening Effect with masking.
    3. Output sharpening to account for the loss created by the output medium. Sharpening applied during export.

    HTH

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  • Angus MacDonald

    Thanks again, Brian for your sharpening explanation.

    However, I'm still trying to find out why simple rotation in crop mode reduces sharpness.

    The screenshot below, from left to right; first photo is with a preset in the Detail Panel of 100 and Threshold at 30. Second is same preset but with slight rotation - notice the reduced sharpness. Third is no preset, no rotation and last is no preset with slight rotation. Again notice the reduced sharpness.

    Why?

    Thanks for your help.

    Angus

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  • Brian Lawson Community moderator

    My best guess is it is inherent in the transformation necessary to do the rotation. The program has to calculate a new position for each pixel in the image according to a Transform Matrix, basically a set of values in a 2D table that defines how the new location is calculated for each axis X, Y, & Z. There are rounding errors that happen during those calculations because of how computers store floating point numbers. Again, this is an educated guess from what I know about computers and the math involved at a general level.

    You should ask tech support about it. Let them ask the engineers if this is as expected or if there is something they can do about it.

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  • Angus MacDonald

    Yea!!

    Thanks so much for your quick reply.
    Your answer is what I kind of surmised might be going on.
    The program can only do so much.
    I did submit this to technical support and am eagerly awaiting their answer.
    I'll let you know what they say.
    If our understanding is correct, then it behooves us to be really careful, keeping horizons level when taking the photo in the first place!
    All the best,
    Angus
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  • Angus MacDonald

    The mystery is finally solved by Tech Support...Merci Beaucoup!!

    The apparent slight loss of sharpness, discussed above, is not due to any failing of the software to maintain sharpness with any transformation - be it rotation in Crop Mode or vertical/horizontal adjustments in Transform mode.

    Rather it is due to the fact that, when viewing the original and the rotated version side by side in Compare in Browse, the rotated photo is a 50% proxy of the original and accordingly appears less sharp. However, when viewed sequentially in Detail or Browse or Edit, the sharpness of the original can be seen to have been maintained in the rotated version.

    This is a huge relief to me, as I had become increasingly reluctant to rotate or transform my photos. A big thanks to Technical Support for explaining how Compare mode really works; it is the 50% proxy that induces the apparent reduction in sharpness, but be reassured, the original sharpness is still there.

    Thanks to all who participated above. I hope this helps others.

    Best, Angus

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  • Brian Lawson Community moderator

    Wow, that kind of negates the usefulness of the Compare mode then.

    Thanks for the update Angus. It's good to hear there isn't any actual loss of detail.

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