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Edge halo oversharpen artefact.

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  • Edge halo oversharpen artefact.

    Want to REALLY sharpen up your images ? Many people don't realise that sharpening creates an unwanted side effect of Edge Haloes, especially where the sky adjoins a darker edge. On some images that we screen we can see this on the thumbnail, never mind the full size image. Take a look at this sectional image. It has been sharpened using one pass of Smart Sharpen and 5 passes of USM sharpening. The edge halo can be seen as a thin white line on the areas where the dark body adjoins the lighter sky.

    Fear not, there is an easy although admittedly slightly time consuming fix but the end result is worth it.

    In Photoshop...
    Go to to Layer...New....Layer.
    In Darken.
    Opacity should default to 100%.
    Click OK.

    Now go to the Clone Stamp tool and select a soft edged 5 pixel size. No bigger than 5 pixels.
    Select a source area in the sky close to the edge of the wing.
    I'll start at the top left lower wing edge and move on to the flap gap.
    Left click, hold and carefully drag the cursor along the white line. It doesn't matter if you stray into the darker tones, the tool will only act on the white line provided that the source remains in the sky.
    When finished, got to Layer....Flatten and click flatten.
    Save at maximum resolution.

    This image shows half of the wing and half of the flap gap treated. Treated areas outlined in red. Notice how much cleaner and sharper the treated edges are...

    You need to ensure that the clone source remains in the sky. Common areas that suffer from these haloes are the lower edges of wings, gaps in flaps, fin trailing edges, lower fuselage edges and around the landing gear. Landing gear haloes tend to be especially obvious and spoil an image easily.
    These last two images are
    1. Processed for upload but NOT with halo treatment and
    2. Fully processed including halo treatment.

    Image 1...

    Image 2.

    Finally, credit for this being brought to my notice is due to Angelo Bufalino.
    Last edited by brianw999; 2015-10-12, 12:28.
    If it 'ain't broken........ Don't try to mend it !

  • #2
    Found it
    Last edited by Bjorn1979; 2015-10-12, 18:40.