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Surely someone can create a neural network that reorients the image, even if the Exif orientation is wrong (JPEG lets you can do this without re-encoding). Soun
by secraetomani 7y ago
Surely someone can create a neural network that reorients the image, even if the Exif orientation is wrong (JPEG lets you can do this without re-encoding). Sounds like it should be a very simple problem for the vast majority of "regular" images.
- machinelearning 7y agoOr how about just use the damn exif information to orient it correctly as the article outlines? The actual article is far less interesting than what the title seems to imply. While the title suggests a problem with computer vision. This is more of a programmer logic error.
- secraetomani 7y agoI've encountered plenty of pictures with incorrect EXIF orientation, mostly caused by holding the phone at a weird angle. For example, if I hold the phone parallel with the ground (aimed at the floor), what is the correct EXIF orientation?
- magicalhippo 7y agoThere are many times my phone detects I'm holding it horizontally while taking a picture, but I'm actually trying to take a vertical picture, and vice versa. For those images, the exif information is technically correct, but actually wrong.
- machinelearning 7y agoIf exif information is incorrect, that's just programmer error at the firmware/library level.
- SiVal 7y agoEXIF info is often missing or wrong. Photos that have been passed around, going through various services, apps, scanners, screenshots, etc. along the way, frequently have their EXIF info stripped (e.g., for privacy when exported or uploaded), written incorrectly originally (e.g., you scan an old B&W print, put it in sideways to fit in the scanner, and the scanner invisibly includes EXIF data assuming it was correctly oriented), or rewritten incorrectly (e.g., stripped EXIF is replaced with default orientation).
- ska 7y agoexif is a bit of a swamp, and may well be missing entirely.
- fireattack 7y agoJPEG lossless rotation can only be done if the dimensions (height and width in px) of the image are multiples of MCU (typically 8x8 for 4:4:4 or 16x16 for 4:2:0).
- klyrs 7y agoSure, that's a good enough excuse. I look forward to defeating government facial recognition algorithms by holding my head at an angle.
- zaat 7y agoFor the uninitiated, MCU is not Marvel Cinematic Universe as the search results might try to confuse you. It's Minimum Coded Units, and a nice explanation is over here: >https://www.impulseadventure.com/photo/rotation-partial-mcu.html https://www.impulseadventure.com/photo/rotation-partial-mcu.... Edit: the link also closed for me a forgotten open loop about the meaning of an annoying error message Windows XP era. Thanks for making me look it up!
- fireattack 7y agoImpulseAdventure is THE place when I look for reference related to anything about JPEG. He also has a very useful utility (I normally use it to check DCT table) called JPEGSnoop [1]. [1] https://www.impulseadventure.com/photo/jpeg-snoop.html https://www.impulseadventure.com/photo/jpeg-snoop.html
- swiley 7y agoBetter (in this case) would be to use algorithms that take advantage of rotational symmetry. What do you do when the phone is at 45 degrees?