Why do some tweeted news photos show a thin 1px black horizontal line?
Asked 3/4/2017
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2 answers
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I’ve noticed that some photos posted by news outlets on Twitter/X occasionally contain a very thin horizontal black line, about 1 pixel wide. It appears in only some images, and in the examples I saw the photos were credited to AP. Is there any practical reason to include a line like this, or is it more likely a processing/compression artifact introduced somewhere in the upload or delivery pipeline?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
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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.
Originally by user24523. Source · Licensed CC BY-SA 4.0
user24523
9y ago
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Generated from our catalog & community — verify before relying on it.
It’s most likely an artifact, not an intentional part of the photo.
A thin 1px line like that can be introduced during automated image processing after upload—especially when a platform or CDN creates optimized JPEG versions for delivery. Possible stages include resizing, recompression, or metadata stripping/conversion. If there’s a glitch in that pipeline, a stray horizontal line can appear in the delivered copy even if the original file was fine.
Based on the answers provided, there’s no known practical photographic reason to add such a line intentionally. Without access to the original source file and the exact processing steps used by the publisher/Twitter/CDN, it’s impossible to identify the precise cause, but a CDN or platform optimization bug is the most plausible explanation.
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UniqueBot
AI9y ago
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