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Sharpness question

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  • Sharpness question


    I recently had a lot of pictures rejected for "oversharpen" and as I usually do not have so much rejecte for this reason I just would like to understand.

    Here are a few examples.

    Number 1 :
    Number 2 :

    Is it only for the blades or for all the image ?

    Number 3 :
    No blade here but perhaps for the red lines which are a little bit jagged ?

    Number 4 :
    This one has also been rejected for another reason "backlit".
    Is it really backlit ? (as I only see a little portion of shadow on the picture)

    Number 5 :
    Perhaps because of the propeller ...

    And last one :

    I know that it represents a lot of questions (I insist, no critisism against any screener) but if you have some minutes to give me your enlighten advises ... I would really be grateful.

    Thanks a lot for your help.

    Have a nice week-end.

  • #2

    Oversharpen is when the lines in the image have taken on a jagged appearance due to applying a little to much sharpening in post processing. Which is something we can see on all the images around cheat lines, propellers and text when sharpening images do you use the rubber tool to rub out the jaggies that appear?

    Number 4 I can't comment on the backlit but again jagged edges on text and lines.

    Number 5 Again text and cheat-lines have a jagged appearance and did you select small prop category because I think that would apply.

    Number 6 The detail in shark is jagged aswell as the general text and cheat-lines. I don't what special categories would apply to this image maybe a screener could explain that.

    I have scripted my method of sharpening below which seems to work for me which i've used on most of my 39 photos.

    After doing all other editing processes I do sharpening last

    Before applying any sharpening using Magic Wand I create a selection to ensure I only sharpen the aircraft and not the sky and other dead space areas.

    To do this just select magic wand and click in the dead areas and they should then have the white and black lines round them keep going until the lines follow the outline of the plane then inverse the selection or you'll be sharpening the dead space not the plane.

    1: Duplicate Layer
    2: Apply 25% USM at 0.5 Radius Threshold 0
    3: Any jaggies I rub out.
    4: Duplicate again and add the same sharpening settings, but I know turn the layers below the layer I have applied sharpening to off so I can see the white/gray blocks were I have rubbed out any jaggies.
    5: I then keep sharpening on a new layer 25% percent each time turning off each layer off as I go rubbing out the jaggies that occur on each layer.
    6. Once I feel the image is sharp enough which is something I sometimes struggle to gauge accurately but go with your gut instinct.
    7. I then merge the layers back together one by one by using merge visible I only turn the layer below on,
    So if I was on Layer 7 id only have that and Layer 6 visible.
    I will then be able to rub out any jaggies that I may have neglected earlier on.
    8. Once all the layers are merged back together I look at the overall sharpness of the image.
    Just to make sure this is clear to turn layers on or off click the eye tool on the layers pallet next to each layer.

    Hope that helps.


    • #3
      Thanks for your explanation.
      Will try your method.


      • #4
        Hi Murmeldeier,

        Just a quick opinion on each one:

        No.1: A good place to look for over sharpening is landing gear, which is generally small and quite detailed. You can see here the diagonal strut almost looks like a dotted line and the wheel itself has a distinctly jagged appearance. The rear of the aircraft and the front slope of the windows also have distinct jaggies.

        No.2: No landing gear here but again, a very distinct jagged look to the front curve instead of a smooth line. Thereís also a slight contrast issue here, the darks should be a little more pronounced and bold.

        No.3: The red line is indeed jagged, as again, is the landing gear. The registration is starting to have that Ďharshí appearance that over sharpening usually gives.

        No.4: Landing gear, prop, cockpit canopy and various other areas showing signs of over sharpening. This is indeed backlit, as can be seen by the position of the aircrafts shadow which very clearly shows the light is coming from the opposite side. You can see the little bit of the engine air intake is very bright white because itís been hit by direct light but the rest of the aircraft is quite dull by comparison.

        No.5. The cockpit, vertical stabiliser and landing gear are all quite jaggied.

        No.6. Lines around the shark mouth, the landing gear and cockpit all appear jaggied.

        As far as sharpening is concerned, Iíve seen some peoples sharpening workflow that involves between 5 and 15 steps, and I really donít believe this is right. Quality is lost with every single editing step you make on a JPEG, and as JPEG is an already compressed format you really donít want to do that. The best results come from the least processing, and so my sharpening is very simple. On the RAW file I sharpen to 110% at a radius of 0.6, and then usually add another little bit of sharpening after resizing, and thatís usually 30% at a radius of 0.3 (the larger the image, the bigger the radius needs to be).

        It actually looks as though the radius youíre using is too large for the image size youíre working with. As an example of the difference adjusting the radius makes, the first image here has been sharpened at 200% with a radius of 0.8. Itís 1024 pixels wide and 0.8 is far too big a radius for such a small image. You can see the overall appearance is very harsh. The landing gear, front gear bay doors, smaller titles on the engine and the antennae on top of the aircraft are all looking very jagged and unnatural and thereĎs a very distinct white halo around the fuselage.

        This has been sharpened at 200% but with a radius of 0.3. Itís still oversharpened because 200% is far too much, but still, the effects of the oversharpening are now much more subtle. Everything looks smoother and not as harsh, the halo is reduced and the overall appearance is much more as your eye would see it in real life.

        Sharpening is possibly the hardest aspect of digital photography to master, but if you know what to look out for then you can generally avoid over sharpening. Again, look for the smaller details like the landing gear and the registration and lines that run diagonally. Itís usually in these areas oversharpening shows itself.

        Hope that helps.

        Seeing the world with a 3:2 aspect ratio...

        My images on Flickr


        • #5
          Yes, it is really helpfull !

          Really thanks for taking the time to give me an answer.

          Have a nice evening.