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by LeifCarrotson 205 days ago
Some systems seem to produce images where the pixel arrangement matches the sensor layout, which moves when you rotate the device, and they'll add EXIF metadata to indicate the orientation.

Other cameras and phones and apps produce images where the device adjusts the aspect ratio and order of the array of pixels in the image regardless of the way the sensor was pointed, such that the EXIF orientation is always the default 0-degree rotation. I'd argue that this is simpler, it's the way that people ignorant of the existence of the metadata method would expect the system to work. That method always works on any device or browser, rotating with EXIF only works if your whole pipeline is aware of that method.
1 comments
taeric 205 days ago
The advantage of the EXIF approach is you don't have to do nearly as much post processing of the data? In particular, I don't expect my camera application to need to change memory layout just because I have rotated my camera. So, if you want it to change the rows/columns on saving the image, that has to be post capture from the sensor. Right?

I think this is what you meant by "some systems" there. But, I would expect that of every sensor system? I legit never would have considered that they would try the transpose on saving the image off the sensor.

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Dylan16807 204 days ago
The transpose is absolutely trivial compared to debayering and compression. It's a lot simpler to do it upfront and not worry about rotation at any later point.

And the odds are very high your camera app did already switch memory layouts when you rotated, at least for the UI. Doing that isn't a big deal.

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taeric 202 days ago
I mean, I get that it isn't incredibly difficult, but it still feels unnecessary. The cynic in me thinks this explains a bit of why the app based cameras are garbage.

Do you expect the same when recording video if the user rotates the device while recording? Timestamping an orientation flag is trivial. Why not lean on that?

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Dylan16807 202 days ago
Video that rotates partway through doesn't have a trivial answer for how you're supposed to display it.

For anything that has a consistent orientation, storing it that way removes a bunch of annoying edge cases and is very simple to implement.

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