Why does file size double when exported?

[jburrows500]

I find that if I have a JPEG at say 3.'MB in my catalog when I export it to the desktop at 1''% it balloons to 5.8MB. I don't understand that. This is on files that I have done no adjustments to... Is anyone else experiencing this and if so, why does LR do that and can I correct this without scalling back to 5'% on export and loose quality.

 

[DonRicklin]

Are you export to JPEG or 'As Original'? If you have not tried the latter, see if that makes a difference.

Don

 

[Brad Snyder]

I've noticed with many applications, not just LR, that saved jpg file sizes vary with the quality selected, which makes sense. What doesn't make sense (a least on the surface), is that if you import a low-quality # jpeg into an application and export it with a high quality #, it comes out larger than it went in.

However counterintuitive that sounds, it's an observable phenomenon in most/all jpg applications. Here's a similar thread referring to the same issue in Photoshop

http://photo.net/digital-darkroom-forum/''FaG'

And there are a couple of references to the phenomenon embedded very deep here:

http://www.impulseadventure.com/photo/jpeg-compression.html

I'm going to say that the size result of the LR export is going to depend very highly upon the LR export quality/compression setting as compared to that same setting of the image source. If straight out of camera as jpeg, what compression/quality choices were made in the camera output settings?

 

[Mark Sirota]

While Brad speaks the truth, I think Don's on the right track -- if you haven't made any adjustments in the Develop module to a JPEG file, you should export as Original. That will write out the original image data unchanged (and will include any new metadata), so you won't suffer from JPEG recompression.