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I don't remember the name of this problem and it drives me crazy. I googled everything similar to "lines in photo" but I didn't find the solution.

The problem is that on my PC monitor I don't see anything, but when I download the photo on my smartphone I see these lines that surround the source of light. I know that some of the problem is my not-top-quality smartphone screen, but I also know this problem has a name and it comes out, for example, when you save an img in really low quality.

I attach the screenshot I took on the smartphone (the only way I can see the problem also on the PC monitor):

enter image description here

  • This can also happen in low quality image viewers, more so if there is colour space attached to image (very likely). – Euri Pinhollow Oct 29 '17 at 13:26
  • @EuriPinhollow Eexactly! What came out in the end is that AirDroid has a really bad image viewer. I visualized it then in the default image viewer and the banding problem disappeared – Brigo Oct 29 '17 at 13:31
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Probably the word you search is "banding". You can get more information here.

Quoting:

Colour banding is a problem of inaccurate colour presentation in computer graphics. In 24-bit color modes, 8 bits per channel is usually considered sufficient to render images in Rec. 709 or sRGB. However, in some cases there is a risk of producing abrupt changes between shades of the same color. For instance, displaying natural gradients (like sunsets, dawns or clear blue skies) can show minor banding.

Colour banding is more noticeable with fewer bits per pixel (BPP) at 16–256 colors (4–8 BPP), where not every shade can be shown without dithering.

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    The word I didn't remember was "posterization" and I found it thanks to your link to Wikipedia, but "color banding" is definitely the most proper name of the problem! Thanks Romeo – Brigo Oct 29 '17 at 10:49
  • @brigo "posterization" is much more specific name for this problem though, banding can be name for several mode defects like shadow noise, FPN and aliasing. "Posterization" reflects that there are large solid areas with clearly visible border between them. – Euri Pinhollow Oct 29 '17 at 16:43
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This is color banding (not to be confused with "banding noise", which is entirely unrelated). It can be caused by posterization due to insufficient bit depth for smooth gradations in a small color range ­— or can be a common artifact of JPEG compression.

This question How to get a smooth gradient on sky? has some suggestions on how to deal with this in general.

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