• Welcome to the Lightroom Queen Forums! We're a friendly bunch, so please feel free to register and join in the conversation. If you're not familiar with forums, you'll find step by step instructions on how to post your first thread under Help at the bottom of the page. You're also welcome to download our free Lightroom Quick Start eBooks and explore our other FAQ resources.
  • Are you using the cloud-based Lightroom apps for Windows, Mac, iOS, Android, Apple TV and Web? Then you'll love my new book, Adobe Lightroom - Edit Like a Pro!

    You'll learn how to use the Lightroom cloud ecosystem to organize, edit and share your photos. You'll also come to understand the thought processes used by professional photographers when they're editing their own photos, so you can transform your photos quickly and easily. And better still, the eBooks are updated for every release, so it's always up to date.

Size of Files exported from LRCC

mikebore

Member
Joined
Jul 11, 2008
Messages
58
Lightroom Version
2.1.1
Operating System
macOS 10.14 Mojave
Arising from another thread I did some tests, exporting an image from LRCC on my Mac and then on my iPhone with some puzzling results:

Starting point: 5472 x 3648 px JPEG file downloaded to desktop with Finder via a card reader 13.6MB

Imported the above into LRCC.

File exported as "maximum available" from LRCC on Desktop computer 8MB

File exported as "maximum available" from LRCC on iPhone 4.4 MB

File exported as "export original" from iPhone 13.6MB.

Another test showed that the "export original" is indeed the original, without edits, as expected.

Why are the max available exports not 13.6MB?
Why is the iPhone export smaller than the Desktop export?

The exported files were all full resolution so there must be some extra compression going on. Is there a setting in LRCC to control compression?

As expected, when I exported from the iPhone it said it was downloading. I don't store originals on the computer either so it must have downloaded there as well.

When I repeated the above, exporting the same photo out of Apple Photos it was 13.6MB when exported from both iPhone and Mac.

Thanks very much for any clarification.
 

mikebore

Member
Joined
Jul 11, 2008
Messages
58
Just discovered that the export from Apple Photos was only 13.6MB if the photo was unedited. If edited, the export was 7.6MB.

This implies another compression step, and that maybe LRCC also does another compression before export, unless "export original" is being used.

Doesn't explain why the export from the iPhone is smaller
 
Last edited:
Joined
Feb 1, 2010
Messages
11,517
Location
West Sussex, UK
Lightroom Experience
Advanced
Lightroom Version
Classic 8
There are two things which control the file size when an image is "exported" in jpeg format....resolution (i.e. pixel dimensions) and the amount of compression used when creating the jpeg (aka "Quality" in LR Classic). You have a degree of control over resolution when exporting from the LRCC apps (though the desktop version has more flexibility than the phone/tablet and web versions), but the amount of compression is fixed in the app, and is not yet constant throughout the LRCC ecosystem.

So you can select "Maximum Available" in both LRCC desktop and LRCC iOS, but that only determines that the pixel dimensions will be the same, i.e. as per the cropped image (or full resolution if the image is uncropped). From my own testing, LRCC desktop uses a compression setting equivalent to around 90 in LR Classic, whereas LRCC iOS (and LRCC web) appear to use a compression setting equivalent to around 70 in LR Classic.

Both of these different settings should produce images which are perfectly adequate for on-screen viewing (although the file-sizes will, as noted, be different), though if planning on printing I'd suggest the LRCC desktop exports would be better.
 

mikebore

Member
Joined
Jul 11, 2008
Messages
58
Thanks for the explanation Jim,

I agree the reduced size is not much of a concern in practice, though I would be happier if LRCC iOS used the same as LRCC Desktop.

Difficult to see a reason for this either, since almost by definition, 'exporting' implies the file is going to be used on another device (not an iOS device where space tends to be lower). It means if I want to email that family group to my brother-in-law for printing I shouldn't use my phone (but I could use Apple Photos!...or use "export original" and let him edit it).
 
Joined
Feb 1, 2010
Messages
11,517
Location
West Sussex, UK
Lightroom Experience
Advanced
Lightroom Version
Classic 8
Not sure why the compression is different, maybe when the iOS and Web versions were being developed they figured that social media sharing would be mostly used, so probably not much need for very large exports.

Personally, I'd just use the LRCC desktop version if I needed a file good enough for printing, then email that.
 
Top