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Image upload error? (self.main)

submitted 6 months ago* (last edited 6 months ago) by threelonmusketeers to c/main

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Error message when trying to post an image:

Slightly different error on mlmym interface:

Funnily enough, I seem to be able to upload these small screenshots embedded in a post just fine. The photo I'm trying to upload is less than 2 MB. Is that too large?

Any relation to these problems?

Any other info which might help diagnose the problem?

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[–] threelonmusketeers 1 points 6 months ago (1 children)

Wow, that's some amazing digital detective work!

I haven’t investigated that extra data much.
It might be part of a ‘capture the flag’ game, or not.

Huh, interesting!

If you would indulge me, I have a few additional questions and suggestions:

Q1: Do you know if it would be possible to implement tools to detect and discard invalid data automatically?

metadata is stripped so people don’t unwittingly share their geolocation

Good to know; I had wondered about how metadata was handled.

Q2: Is metadata stripping unique to this server, or a Lemmy-wide standard?

If I recall, the size limit is 5M.

Q3: Is this limit set on a per-server basis, or a Lemmy-wide standard?

Q4:Would it be possible to implement automatic compression of large images?

Most modern phone cameras routinely take larger photos than 5MB.

Just some off-the-cuff suggestions, and I'm not even sure whether they would be best implemented by the instance or the platform.

Thanks for all of your help already!

[–] InEnduringGrowStrong 2 points 6 months ago (1 children)

A1: probably, although that's more processing power. The tool I used to fix it would have outputted a second image file if the extra data had been an image, which is then a weird case to handle. (Upload both? Make 2 links?) Certainly, it could output a better error message though.

A2: Should be lemmy-wide, although technically a malicious server could disable that somehow, which I think would only affect their local users. ie: don't make an account on a server you don't trust.

A3: It is a server specific setting. It's easy enough to change the setting. Bigger limits uses more storage which costs money

A4: Possible, I would think. No idea if that's ever on the devs' roadmap. I think that would be added to the pict-rs code which is then used by the lemmy server.
Both are open source projects, so an instance implementing this could then share the code so it's eventually a feature for everyone.

I've ran into bugs before on some public image host I don't remember where it wouldn't strip metadata if you uploaded an album. It's probably a good practice to strip metadata before uploading, although much less convenient. I double-check that it still works here from time to time, doubly so after upgrading versions.

[–] threelonmusketeers 1 points 4 months ago* (last edited 4 months ago)

Thanks for your detailed answers!

A4: Possible, I would think. No idea if that’s ever on the devs’ roadmap. I think that would be added to the pict-rs code which is then used by the lemmy server.

I came across these discussion threads in the Lemmy and Pict-rs source code:

Is it possible that automatic compression has already been implemented? Might it just be a matter of passing an additional argument to pict-rs?