Difference b/n Collect + Enketo - low image resolution

My apologies if this is already covered, I searched for a bunch of related terms and didn't find what I was looking for, nor is it mentioned in the differences doc

1. What is the issue? Please be detailed.
When adding images to a form in Enketo, the resolution depends wholly on the browser zoom state and display panel resolution.

On my a laptop with 1920x1280 panel resolution, with a form that loads default PNGs for annotation, (all PNGs have resolution 2960x2107 to match the largest tablet resolution, all image widgets have `max-pixels=2960'), the PNG returned from Enketo has increased colour depth and image width of:

  • Loaded at 100% - 616px
  • Loaded at 100% and then zoomed to 200% - 1232px but image is just a 1:2 scaled 616px image
  • Loaded at 200% - 1232px
  • Loaded at 300% - 1590px
  • Loaded at 500% - 1635px
    (non linear increases after 200% due to running out of screen to render on)

Testing same on a screen with resolution 3840x1600:
Image width when loaded at different zoom levels (downloaded from unsubmitted form, not form submissions)

  • Loaded at 100% - 616px
  • Loaded at 200% - 1232px
  • Loaded at 250% - 1540px
  • Loaded at 300% - 1848px
  • Loaded at 400% - 2464px
  • Loaded at 500% - 3080px

Of note, all unannotated images downloaded had filename jr___images_SOURCEIMAGENAME-HH_MM_SS.PNG except one at 300%, which downloaded as SOURCEIMAGENAME.PNG, and this image retained the low colour depth, original resolution as uploaded to Central, i.e. it's the original image, I haven't been able to repeat this once off behaviour with the same default image or other images after ~20 tests. Annotated images had filename annotation-SOURCEIMAGENAME-HH_MM_SS.PNG

Non default images uploaded (Click here to upload file (<100mb)) exhibit the same behaviour, eg a 2587px wide JPG at 200% zoom returned a 1232px wide PNG

Impact - Cannot complete a form in web OR edit a submitted form, as any images added/annotated will be extremely low quality, unless an ultrawide display panel is available and the enumerator navigates in the difficult 500% zoom level.

2. What steps can we take to reproduce this issue?
Load a form with an image widget in Enketo, add images at different browser zoom levels and check the resulting image dimensions.

3. What have you tried to fix the issue?
Upload without modifying / upload at different zoom levels

4. Upload any test forms or screenshots below.

Thanks for detailing the current behavior. That's not intentional and I've filed an issue at https://github.com/enketo/enketo-express/issues/447. I'll update when we have a sense of what a fix will look like and when it's likely to come.