P: Exported JPEGs have pixel-based metadata making large files - option to discard

[erkerkerk]

App version 7.1.2 (macOS, 13.6, Intel)

Just like it says in the title: my JPG exports are way too large in size. A 90%-quality JPG is 31.4MB, which is fine, I guess, but dropping that down to 30% quality and 500 pixels on the long side results in a file that is 30.8MB! This isn't a problem with the size estimate in the export panel either: I'm looking at a 30.8MB image that has terrible JPG compression artifacts and has dimensions of 333x500! I've attached it for your amusement. There's basically no information in this image and yet it's enormous! What is going on here?

I've had the same results on an Apple Silicon Mac and my iPad was also reporting large export sizes, though I didn't experiment with it as much there. To be fair, this is a large Lightroom file with lots of masks, but that shouldn't matter when it's flattened into a JPG.

For what it's worth, when I export to Photoshop and use the export feature there, a PNG file size at original res (which is only 1727x2591 btw) is computed at 5.6MB, and a JPG with 7/7 quality at 2.3MB. Both of those are much more like it. What's going on in Lightroom??

[Rikk Flohr: Photography]

I am not able to replicate what you are seeing.

Starting with a 5D Mark IV raw file and exporting at 500 PX Long Edge and 90% quality, I see around 140 KB, and at 30% quality about 70KB - hundreds of times smaller. I think you would be best served by showing us a screenshot of your export settings - all of them so we can determine what is happening. 

It also wouldn't hurt to post the original file you are using to generate your export. 

  

[erkerkerk]

What kind of export would be most helpful? "Original + Settings"? Will that get you all my masks and everything? It says it'll produce a 44.8MB file. If I can attach that here and it'll be useful, I'll do that.

Meantime I'm attaching two screenshots. One, 30pct-small, shows the 30.8MB size of a file at 30% quality and 500px width. The second, 90pct-large, shows the 31.8MB size file at 90% quality and original dimensions.

[Rikk Flohr: Photography]

I asked for the original - not an export.  Are you able to supply that? If not, then I would need the original plus settings as I can disregard the settings. 

Concerning your settings. If you uncheck All Metadata how does that affect file size? 

[erkerkerk]

Okay, you landed on the reason for the large file size: switching from "All Metadata" to "Copyright Only" brings that file down to an appropriate 48KB file size.

Now the obvious question - what is this 30.4-ish megabyte metadata?? Although this gives me a path to a smaller file size, I need the export to have all the EXIF data, especially GPS coordinates. This still seems like a bug to me. Doesn't it to you as well?

I don't have an option to export "Original" only in Lightroom - only Original + Settings. And I think since we've identified the metadata as an issue, you may need to be able to see it in order to see what Lightroom is doing. Sadly at 49-ish MB, the original RAW alone is too large to attach to this forum so I've put it in this Google Drive folder along with the XMP sidecar: https://drive.google.com/drive/folders/1o3fs2f2CY1xpxn5WQMKKvEYOZVIrku6Q?usp=sharing

[Rikk Flohr: Photography]

An exported JPEG with all metadata will include any pixel data for AI Selections, or Content-aware remove spots. Saving with All Metadata off eliminates those items from the final JPEG. 

The behavior is currently as-designed and not a bug. 

I have converted this to a feature request for having an intermediate save option that omits the pixel data but keeps other metadata. 

[erkerkerk]

Thank you, Rikk. I did use AI selections for the first time on these pictures and unfortunately I now regret it. I feel I've bumbled into a trap by using that feature, since I apparently also lack a way to turn AI masks into regular pixel masks, so my JPGs are now going to be 30MB at minimum unless I can live without exif data (which I can't and don't think anyone should have to). As for this being as-designed, I'm a little muddy on the use case for having the pixel data you described go along for the ride as metadata for a JPG, given it can set such a high floor on its size in the process, but I know I have to defer to you there.

This must be affecting others as well and I hope this feature request gets the attention it deserves. It's certainly not working the way I intend it.

Finally, if my frustration bleeds through my words a little, that shouldn't suggest that I don't appreciate your assistance, because I most certainly do.