1. What is the problem? Be very detailed.
I really hope I've missed something simple here, but I can't seem to get reasonable image sizes unless I really reduce the max-pixels value, which isn't practical.
Image quality ex ODK Collect appears to have zero jpg compression and actually inflates image file size.
Resized images (to ~40% area) are similar in size to the original file, unresized images are nearly double the original size.
Image quality ex marked up ODK Collect is dramatically reduced in size however, close to a 75% irfanview jpg. (see 4c vs 4e)
Externally saving a sample image at 100% jpg quality is barely larger than the no resize Collect image (5a vs 1b & 1d) or actually smaller (5b vs 2c)
Externally saving the images at 75% jpg quality results in around a ~5x reduction in size from ODK or ~2.5x reduction from device camera.
Increases data volume & time to upload/download, consumes 2-5x DB space unnecessarily.
2. What app or server are you using and on what device and operating system? Include version numbers.
ODK Central 1.3.3 (client 1.3.2)
ODK Collect 2021.3.2, Android 11, Samsung Galaxy Tab S6
3. What you have you tried to fix the problem?
Adjusting device settings
Testing different combinations of max-pixels and capture vs select image (see (#5))
4. What steps can we take to reproduce the problem?
Capture a photo and compare file sizes
5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.
Previously the default camera could be changed to one that has options for capture resolution and JPG quality (eg Open Camera) but this is not possible anymore and the only options on recent Samsung devices are HEIF (not available in Collect) or JPG, no resolution/quality options. But it doesn't seem that this matters, as even selecting a gallery image (eg 1a) can result in a file size that's similar (with a 60% shrink 1c) or larger (no resize 1d & 1d).
Testing with Galaxy Tab S6, sensor resolution 4128*3096:
1a. Samsung camera capture outside Collect, original size 4.12mb
1b. 'choose image' using above photo, max-pixels=4128, 7.1mb
1c. 'choose image' using above photo, max-pixels=2560, 3.8mb
1d. 'choose image' using above photo, no max-pixels, 7.1mb
1e. 'choose image' using above photo, select annotate image but don't markup, just save & close, gives 2134x1600 (1600 screen pixel width) image, 0.5mb
'Take Picture' of as close to same scene as above photo as possible,
2a. max-pixels=4128, 5.1mb
2b. max-pixels=2560, 3.1mb
2c. no max-pixels, 8.8mb
Open Camera, capture as close to above scenes as possible
3a 4128x3096Q75: 1.2mb
3b 4128x3096Q100: 5.6mb
3c 1440x1080Q75: 0.2mb
Irfanview save as jpg, quality 75:
4a : 1a 4.12 --> 1.6mb
4b : 1b 7.1 --> 1.6mb
4c : 1c 3.8 --> 0.7mb
4d : 1d 7.1 --> 1.6mb
4e : 1e 0.5 --> 0.5mb
4f : 2a 5.1 --> 1.3mb
4g : 2b 3.7 --> 0.7mb
4h : 2c 8.8 --> 1.6mb
Irfanview save as jpg, quality 100:
5a : 1a 4.12 --> 7.5mb
5b : 2c 8760 --> 8739kb
Annotated image resolution appears to be a limit of device screen resolution since at least 2012. I have chosen a high res device to work around this, but if it is eventually resolved it would open up the use of cheaper and physically smaller devices without sacrificing annotated image quality (or having to capture an image without annotation and also capture one that allows annotation).
I don't know if this is even possible or probable, and I can work with a ~2MP annotated image, but thought I'd tack it onto this post as a side note.