I have noticed that couple of times, in particular with LA Times Twitter account. Some images posted there contain horizontal black line, approximately 1px wide. It is not my screen being funky. I have asked LATimes, but got no reply, and googling didn't help.

Is there practical reason to have that line or is that an artifact of some processing?

Example 1, Example 2

In both examples images are credited to AP (Associated Press). Also, of course, not all images in that twitter have such lines.

Example 1

Example 2

  • \$\begingroup\$ I think it's a mistake in the camera. Interesting. \$\endgroup\$
    – Sedat
    Commented May 24, 2017 at 12:40
  • 1
    \$\begingroup\$ I don't think it's a camera issue. Here's the image without that line: univision.com/univision-news/immigration/…. There might be a problem with a post-processing (downscaling?) routine used, that randomly introduces these lines? \$\endgroup\$ Commented May 25, 2017 at 12:45
  • \$\begingroup\$ Are you sure it's actually part of the image and not some bad CSS on the website that causes something to get drawn atop the image? \$\endgroup\$
    – dgatwood
    Commented May 25, 2017 at 20:24
  • \$\begingroup\$ @dgatwood yup, the images are saved JPGs from tiwtter \$\endgroup\$ Commented May 25, 2017 at 21:20

1 Answer 1


This seems to be related to an aberration added due an “optimization” process occurred while the jpg file was uploaded to the CDN (content delivery network) in this case “https://pbs.twimg.com/media/XXXX”. This is pure speculation but a possible cause is that a glitch in the optimization algorithm added the undesired line. Sometimes when the CDN strips the file or picture metadata (EXIF, XMP, etc) in order to provide an optimized version of the file for mass distribution.

Once again this could be a possibility in this case but without source information it is impossible to know.

  • \$\begingroup\$ This was my thought as well. It's unfortunate that we probably won't be able to know for sure. \$\endgroup\$
    – scottbb
    Commented Jun 6, 2017 at 18:44
  • \$\begingroup\$ Indeed, as long as it does not become a major drawback, I don't think they (Twitter or LA Times account managers) will officially report anything about it. \$\endgroup\$
    – James
    Commented Jun 6, 2017 at 20:32
  • \$\begingroup\$ thanks, that didn't come to my mind at all. Interestingly, I only seen that on LA Times feed, nowhere else. \$\endgroup\$ Commented Jun 7, 2017 at 4:06

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