I didn't think about compressing the image before uploading, so the image I uploaded is 43mb while the compressed one I made is only 5mb, but I don't know how to replace the first one.

Why do you want to compress the image?

noveltwin said:
I didn't think about compressing the image before uploading, so the image I uploaded is 43mb while the compressed one I made is only 5mb, but I don't know how to replace the first one.

Generally you shouldn't do that, especially if you mean by converting a lossless png to a lossy jpg. Lossless pngs are far more preferred to lossy jpgs, since jpg compression irrevocably adds noise to the original image. E621 has file size limits, and if the image is under the limit, it's fine. At most, you could try running optipng or something on it, but I don't imaging it'd bring down the file size enough for the servers to care.

watsit said:
Generally you shouldn't do that, especially if you mean by converting a lossless png to a lossy jpg. E621 has file size limits, and if the image is under the limit, it's fine. At most, you could try running optipng or something on it, but I don't imaging it'd bring down the file size enough for the servers to care.

I just noticed viewing the upload on mobile had a chugging loading time, even if on PC it's near instant. Not to mention I looked at other submissions and they're almost always under 5mb in size. I just thought the file I uploaded was inconveniently too big.

You should always upload the best available version of the image. Don't deliberately compress an image before uploading, it'll just be deleted as soon as someone comes across the uncompressed version.
43MB is hardly the largest file uploaded to e621: order:filesize. The supported formats and size limits are listed here.

If it takes you too long to load an image on mobile, you should switch the "Default image width" to "Sample" in your settings.

The only way I can see a full size version being an issue is if the full size is Patreon material or DNP

bitwolfy said:
You should always upload the best available version of the image. Don't deliberately compress an image before uploading, it'll just be deleted as soon as someone comes across the uncompressed version.
43MB is hardly the largest file uploaded to e621: order:filesize. The supported formats and size limits are listed here.

If it takes you too long to load an image on mobile, you should switch the "Default image width" to "Sample" in your settings.

Thank you for that clarification and suggestion. I also messaged Milcore about it so now I feel like I'm overreacting.

Users can use a sample size if they need quicker loaded images.

I'm bumping this because I've wanted to bring up the same issue:

OP likely isn't talking about file size alone; artists often upload massive PNG images because they don't understand how the format works, and
this problem is only getting worse over time.
For example post #2971047 is probably the image they're talking about, when compressed properly it goes from 43mb down to 5.3mb; *87% smaller* The post-compression pixels are identical.

The technical issue is that e6 also stores metadata that includes the original image's md5 sum, which will become different even if the pixels aren't, and could break some searches. I'd propose a tag for "lossless_re-compress" and maybe some field for adding the md5 of the original image.

Somebody with more technical knowledge could probably refine this idea more.