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The photos I have taken with Canon EOS Rebel T5i has lines at the edges between individual fruits. The colors of these lines range from grey to black. I have attached two versions of the same photo, one at 100% and the other at 200%. The lines are visible in both.

Details of the photo:

Camera: Canon EOS Rebel T5i Exposure time: 1/25 sec F-stop: 6.3 Shutter speed: 1/25 sec Focal length: 32 mm

photo at 100% view

photo at 200% view

  • What processing or editing has been done on this photo? Sharpness? Clarity? – scottbb Jul 3 '16 at 15:00
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This happened because camera applied surplus of sharpening. Sharpening means for a computer to find a lightness transition and make the dark part of it darker and the lighter part lighter. If one applies disastrous amount of sharpening (as camera clearly did) artifacts are inevitable - the ligher part will become clipped white and the darker part will become clipped black.

You will get similar artifacts if you use aggressive tonemapping (which is sharpening with very big radius) but at a larger scale.

Here I reproduced the defect which original image has, it is visible on tilted parallel lines. unsharpened sharpened, 1px radius

Solution:

  1. set your camera to apply less sharpening (i.e. find "sharpness" setting and reduce it)
  2. if the sharpness does not satisfy you, increase contrast instead
  3. Record RAW files and set everything in RAW processor.

Another example: glowing outlined

P.S. Mostly copypasted from similar question.

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The camera flash cast hard sharp shadows because the flash is located close to the camera lens and the result is straight on lighting. Because of the close proximity, flash to lens, the shadows cast are a thin line. The shadows are underexposed and void of detail. The countermeasure is use a second “fill-flash” or a reflector. Such a lash-up is adjusted so the shadows receive “fill” light from a second direction. This technique provides shadows that contain detail. We often need shadows to convey a feeling of depth. To this end, they must be illuminated by a light that is subordinate to the main source. When a single flash is used, we diffuse or bounce it off ceiling or a nearby object. Thus the illumining light is coming from more than one direction. Such a technique fills the shadows and they reproduce with less harshness.

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    I have to completely disagree. This photo shows no evidence of lens-axis light sources. In fact, the darkest parts of the individual curved surfaces are the parts that are normal to the lens axis -- exactly where you would expect to see specular reflections from the on-camera flash. This image gives us 2 excellent cylindrical surfaces to judge the lighting (the blue measuring cup, and the jar in the back left). The jar is especially telling: there is a large diffuse light source immediately to scene left; there is a lower-power, possibly point source or dish source scene right. – scottbb Jul 3 '16 at 23:44
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    If you look at the close-up, the lines are clearly not shadows. Shadows would be cast by an object nearer to one of the light sources, and cast on something "behind". In this image, the dark lines are a very even, dark halo around the object, and do not vary with differing orientations to the main light source, nor do they vary with regard to the contours of the background objects they supposedly are cast on – MikeW Jul 3 '16 at 23:45
  • ... and no source along the lens axis, thus the darkest-lit portion of jar, without any light reflection, in the vertical center. – scottbb Jul 3 '16 at 23:45

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