Save up to 67 Percent of Your Disk Space With Lightroom's DNG Compression

Disk space can be a real burden for photographers who shoot a lot of images per year. Tony Northrup goes through how you can save up to 67 percent of your used space by applying DNG compression to your Lightroom library.

Photographers are digital hoarders. A photo has to be utter horrendous for me to fully delete it from existence. Even if I've taken a portrait where the subject is slightly out of focus and I'm never going to use the image, if the background and bokeh is looking nice, I won't delete it in case I ever want to borrow it for another image (over a decade of this practice and I'm still yet to do that!) Anyway, that's besides the point. We collect volumes and volumes of images and it is demanding on storage. One way around this is to use DNG compression, but due to the word "compression" we never do.

Compression is a dirty word to any digital artist, and one that given the choice, we'd never opt to do. However, as Northrup shows in this video, the impact on your image is — for all intents and purposes — invisible. In fact, to find any noticeable difference in the image, Northrup had to go through different images side-by-side and at an 8:1 ratio before he found an artifact lurking in the form of a small halo. I say halo, it's more of a discoloration and even watching the video full-screen and source quality, you can barely see what he's talking about.

The best part about this is it's all done within Lightroom and there are options to safely delete the original raw files upon successful compression. I am going to be rigorously testing this before I compress my entire library, but this is certainly worthwhile for those less important shoots.

Have you used the DNG compression? Did you find any obvious downsides? Share your experiences and thoughts in the comments.

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Pieter Batenburg's picture

To my astonishment, I found out that most of my DNG files are actually bigger than the original Sony Arw files. So after converting some files, I stopped. The original arw files are all around 24 Mb. The dng files are all bigger with the biggest around 29Mb

Manuel Nibale's picture

The same for me (with an A77 II), i've tried but the resulting file are a little bigger than the original RAW.
I supposed that maybe Sony is already (at least for my type of camera) using the same (or really similar) algorithm than Adobe uses for DNG.
I've tried with old 5D II files and they really benefit of an about 20% less size than original CR2.

Daniel Lee's picture

Is this compressed or uncompressed? The ARW flies from my A7III have been larger than the DNG but I do shoot uncompressed.

Pieter Batenburg's picture

Sony a6300 has only uncompressed files

Matthew Saville's picture

That's because Sony ARW files, the "normal" ones, are already using lossy compression, and doing a better job of it than Adobe. Same thing with Nikon NEF compression, the mid-class and high-end Nikons all let you choose between lossy, lossless, and uncompressed. You can even bump down to 12-bit from 14-bit, if you're desperate for card space.

Basically, this 67% savings option is ONLY useful for Canon and other shooters who have zero alternatives for full-resolution raw files. (Thanks to Canon's silly notion that it's better to reduce the actual megapixels and keep the files at 14-bit lossless, instead of keeping all the megapixels and offering compression and bit-rate options. And yes, a 12-bit lossy NEF file still spanks any Canon CR2 mRAW file...)

Adam Palmer's picture

I have been using lossy DNG for years with no complaints. I shoot a lot of weddings. It's like the best of both worlds. Small file sizes like JPGs and full WB and editing like raw.

Rick McEvoy's picture

I have often thought about doing this but have some underlying fear which stops me. I can live with the file size. Is it just me? I really dont get it.

Rick McEvoy

Steve Bryant's picture

Not just you - do much prefer the RAW data, and don't need another step in the workflow.
Besides, HDD's are pretty cheap... :)

Joe Vahling's picture

Hard Drives are cheap, but I also use cloud storage for backup and approaching that 1TB mark. There's a lot of shots in many events that not only I can compress, I should just out right delete. I've saved even more space using image resizing of shrinking those 40 MP DNGs down to 24 MP or if need be 12 MP for those really non keeper but won't delete them shots.

Ryan Mense's picture

I save 100 percent of disk space by just deleting my trash photos

Michael Breitung's picture

Yea, I just go regularly over my old photos. I found if I go through my 2+ year old photos, it's very easy to clear up 30 - 50% in a first go. I regularly do this to filter out the "trash" I'll never process or post anyway. This way I still have less than 2TB of photos including the master processed files covering the last 9 years.

Matthias Kirk's picture

So, you're saying 100% of your photos are trash?
Don't be so hard on yourself :)

James Mead's picture

Nope, very much lack of a video attached to the article.

Robert K Baggs's picture

Bizarre. Fixed it now — thank you.

Jorge Garcia's picture

I converted years of RAW files into DNG until I started using Capture One, which apparently doesn't play nice with DNG files.

Paul Goossens's picture

Good point. Hmm

Matthew Saville's picture

No, Capture One Pro 11 works fine with DNG files that are converted to a modern enough standard. I use C1P11 all the time to process Lightroom-generated panorama DNG files, and others. (Such as Pentax native DNG files)

Jorge Garcia's picture

Matthew, I really appreciate your response. I upgraded to CapOne 11 recently and was unaware that DNG support has improved. I'm going to convert some photos today and try it out. Thanks again!

Nick M's picture

Something to consider if you're thinking of making the switch to DNGs *and* you use a cloud backup service; edits to the DNG are wrapped up in the file, not stored as a sidecar .xmp. Meaning, if you make even a small edit in Lightroom, the file changes and will be picked up to backup again.

Patrick Österlund's picture

I've thought about doing this, but I'm not sure how many other editors support .dng's. And though I really love Lightroom, it's been acting up to much for me lately that I'm not comfortable enough putting all my nef's in adobes basket.

Lars Sundin's picture

Making a copy and throw away the original, no way. DNG will also make me a lifetime prisoner in the Adobe world. Not for me!

William Faucher's picture

As much as I respect Tony Northrup, I have always had a hard time trusting him. Some of his comparison reviews are so biased, its not even funny. And now, why would I want to convert all my files to a format that only Adobe uses? Disk Space is dirt cheap, the cons of converting outweigh the pros. I am sure this is a solution for many people who are eternal Lightroom/PS users, but for anyone using other software, such as Capture one, knows that C1 prefers native raw.

Edo Photo's picture

Not a chance... this post seems to be somewhat naive and overly general.

Like another comment pointed out, dng's do not work well with some applications. If you're a user of that application then you're out of luck.

I've read the argument that at some point some are afraid that they won't be able to access the raw files anymore....and it always sounds like hogwash. The apps that can open them now aren't going anywhere.

The major companies need you as the consumer to be able to edit these images as most of them do not have their own editing sweet anyway. Lastly the fact that there's no sidecar files for dng makes backing up edits to large sets potentially unbearable, and even how you'll be stuck in Adobe land afterwards, makes DNG certainly a no-go for my workflow.

Dont. Trust. Adobe. Not at all.

Matthew Saville's picture

Adobe's DNG compression is TERRIBLE compared to just using Nikon NEF compression. If you shoot Nikon and care about card/drive space because you shoot massively high volumes of raw stills, (timelapse, sports/weddings) ...then just shoot compressed NEF, and bump it down to 12-bit NEF if you really want to save space.

Believe it or not, the difference between a 12-bit lossy compressed NEF file and a 14-bit lossless NEF file is STILL LESS NOTICEABLE than the loss of quality that comes with using the Adobe DNG compression that could save you 67%...

Aaron Patton's picture

Just did this on a test photo (that I figured it would have a hard time with), and even at 4:1 the artifacting is atrocious. Sure, it dropped a 22.3 MP file to 4.2, but damn.

Matthew Saville's picture

...if you had shot 12-bit compressed NEF, you would have a better quality file! ;-)

Aaron Patton's picture

You Nikon people... ;)

Matthew Saville's picture

Aaron, the correct response was "yeah, but the skin tones would be jaundice, so..." :-P

stefano giovannini's picture

I am looking into this, just tried a comparison. Sony ARW file is 24 MB, DNG is 9 MB whether compressed or not. If I embed original RAW file the DNG appears to be 12 MB, which is strange. I shoot maybe 5 assignments a week for local newspapers. Often dish, arts, fitness / health stories. I care about half of the assignments . I want to cull 50% of the photos. Converting to DNG the jobs I am not passionate about would allow me to condense my libraries on smaller drives. It seems a good compromise. SO far I have almost 8TB of work, I keep on 4 TB drives and 1 8TB backup drive. I am looking at more cons. I am looking at a Lightroom alternative as I do not like the subscription model. The difference in artifacts seem negligible. But I would not like being prisoner of Adobe if my files are DNG. Is and will always be an open standard?