4 Replies Latest reply on Feb 4, 2018 2:40 AM by eliseele

Save space! Migrating 1TB Classic to Lightroom CC

f_r_e Jan 23, 2018 7:36 AM

I am currently preparing my Classic catalog for migration to the cloud based Lightroom CC (2017). My library contains over 100.000 photos, half of them are standard DNG files. The files are all stored on a NAS server in one folder, which is about 970 GB. If I were to migrate my entire catalog, I would quickly run out of space with the standard subscription of 1TB...

I decided to re-encode all my current DNG files with lossy compression. According to my calculation this will save me about 300GB. This will allow me to continue using the 1TB subscription for quite some time.

Compressed DNG files are very similar to the original RAW files. Most users will never notice any difference (search Google for analysis). Professional users might want to skip on compressing their work, or can choose to compress only 3-star or less photos but leave the best shots unchanged.

Steps to compress your current DNG or RAW files in Lightroom Classic:

1- Create a smart playlist searching for DNG or RAW files without compression (+ and/or a second rule based on star rating)

2- Select the photos in the smart collection

3- Choose Library -> Convert Photos to DNG

4- Be sure to discard any previews or smart load data (Lightroom CC doesn't use these, I presume) and enable lossy compression

5- Let it roll!

Later on, after the Lightroom Classic to CC migration is complete you'll want to convert any new photos that you want to import BEFORE adding them to Lightroom CC. Lightroom CC currently does not allow conversion of RAW files during import. For this purpose, you can use the separate stand-alone Adobe RAW Convertor.

This way the standard 1TB tier will go a long way for a lot of people. Just wanted to share the results of my research and nightly sorrows :-)

1. Re: Save space! Migrating 1TB Classic to Lightroom CC

john beardsworth Jan 23, 2018 11:45 AM (in response to f_r_e)

You're putting a lot of time and energy into throwing away image information that you've worked hard to build up. Put off buying that new lens, get extra space if you want to go LRCC, or only import new images (for example). Of course, you are perfectly free to do it if you want to with your own photos, but I would not generally recommend this approach.
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2. Re: Save space! Migrating 1TB Classic to Lightroom CC

f_r_e Jan 23, 2018 10:50 PM (in response to john beardsworth)
Thank you for your reply. I think you are right in that I have indeed spent a lot of time and energy in those pictures.

A suggestion. If people should want to upload their existing catalog to Lightroom CC, they could first make a full copy of their lossless RAW files to a cheap USB-disk and store it indefinitely in a safe somewhere for future reference (if ever needed). With this local backup they can safely compress any existing RAW files.

I want to direct your attention to an article by Google Photo's John Nack (18 June 2014) where he talks about the reasons for compressing his RAW files to lossy DNG and a follow up article by Mike Pasini (24 June 2014).
Heresy: Should I just wholesale blow away my raw files? | Nackblog
mikepasini.com | Photo Corners | Lossy DNG: Heresy Or The New JPEG
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3. Re: Save space! Migrating 1TB Classic to Lightroom CC

john beardsworth Jan 24, 2018 12:34 AM (in response to f_r_e)

Good, now you say "local backup". That is very important for anyone reading this - don't even consider going to compressed DNG if you aren't sure you have a rock solid backup for your originals.

But I still think you'd be better off saving some money on a lens or your food bill and buying the extra cloud storage!
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4. Re: Save space! Migrating 1TB Classic to Lightroom CC

eliseele Feb 4, 2018 2:40 AM (in response to f_r_e)

The lossy compression is only supposed to be used for archiving of images you don't plan to do any developing work with. The image is no longer a raw Bayer image. It is RGB and 8-bit. You are essentially saving a jpeg image with a .dng extension and some metadata.

If you want to shrink DNG images further while keeping the raw aspect alive you may consider using a program like Slimraw (see here: slimRAW: CinemaDNG Lossless and Lossy Compressor for Windows and Mac ). It has a lossless compression mode which converts the image to 10 bits in a non-linear fashion and encodes it losslesslym and it also discards the internal preview images which saves more space. I use this for my photos to shrink my library to the maximum without sacrificing quality.
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