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EXIF orientation info in PNGs isn't used for image-orientation: from-image

(bugzilla.mozilla.org)
94 points justin-reeves | 2 comments | 21 Nov 25 13:29 UTC | HN request time: 0.522s | source
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donatj ◴[21 Nov 25 14:31 UTC] No.46004961[source]▶
Interesting. I was not aware that was a thing. Orientation info seems way less useful in a lossless format like PNG. It makes sense in JPEG for instance because rotating and re-encoding would be lossy and slightly degrade the image.
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1. MontagFTB ◴[21 Nov 25 14:39 UTC] No.46005026[source]▶
Looping through inflate/deflate on rotated pixels still takes more time than updating a bit in the Exif (and the chunk’s associated CRC)
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2. crazygringo ◴[21 Nov 25 15:17 UTC] No.46005341[source]▶
It's still negligible from the consumer standpoint.

Like, if you had millions of images you needed to rotate on a server in a batch job, then OK.

But if you're just rotating one photo, or even a hundred, that you've just taken, it's plenty fast enough.