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Lossy DNG vs RAW in Lightroom: what you keep and what you lose

Published 17 October 2026 · By Ferdi

A lossy DNG is a smaller copy of a RAW file that Lightroom can still edit. It holds less data than the original, so it cannot do everything the original can. Here is the difference in plain terms.

What a lossy DNG is

DNG is Adobe's open RAW format. A DNG can hold the sensor data as it was recorded, or a compressed version of it. Lossy means some of the data is thrown away to make the file smaller. The file is still a DNG, so Lightroom opens it like any other RAW.

Lightroom can make lossy DNGs itself. Greg Benz, a photographer, shows the Convert Photo to DNG option with lossy compression. In one of his tests, a 59.1 MB Nikon NEF came out at 26.8 MB when he denoised it first, and at 21.3 MB when he converted it first.

Mosaic or linear: the detail that matters

A RAW file is a mosaic. Each photosite records one colour, and the software works out the full colour at every pixel. That step is called demosaicing. A linear DNG has already been demosaiced, so every pixel carries full colour from the start. A mosaic file has not.

This matters for denoise. DxO PureRAW needs the mosaic. Our notes say Lightroom AI Denoise will not run on the linear format, but Adobe's help page lists linear DNGs as supported, so test it in your own Lightroom before you rely on either answer. In Squeeze, the "Mac & Lightroom" format is linear. The "Lightroom only" format keeps the mosaic, and our notes say Lightroom's denoise works on it. The catch is macOS. Finder, Quick Look, Preview and Photos show that format black at full size. Lightroom reads it fine.

What still works in Lightroom

Lightroom opens a lossy DNG with the usual controls: white balance, exposure and camera profiles. We expect Fuji film simulations to carry over, but we have not checked every one. In our tests, Lightroom Classic 15.x and Adobe Camera Raw gave full raw controls.

Your saved edits come along too, if Lightroom has written them to the file's XMP sidecar. To make sure it does, turn on automatic XMP writing in Catalog Settings, or select the photos and press ⌘S. The History panel does not travel. It lives in the catalog only.

What you lose

• Some sensor detail. The lossy step throws a little away. At 100%, most of our tests looked the same. Zoom to 300% on fine noise and the grain can look smoother.
• Denoise on the lossy file. We assume DxO will not take a lossy DNG. For Lightroom AI Denoise, our notes and Adobe's help page disagree, so denoise the original first.
• Future colour work. The demosaic step is fixed when you convert. Better demosaicing later will not apply to the file.
• Some software. We have not confirmed that Capture One opens the JPEG XL format, so treat it as no until you test it.

When to keep the original RAW

• Forensic, scientific or evidence work.
• Competitions or clients that ask for original RAW files.
• Shots you may still want to denoise in DxO or Lightroom.
• Tight crops of noisy shadows. Differences can show at high zoom, so check those shots first.

Check it on your own files

Do not rely on anyone's test alone, ours included. Pick five or ten of your own files, convert them at the setting you plan to use, and open both versions in Lightroom at 100%. Apply the same edit to each. Look at lifted shadows and high-ISO noise. If you cannot see a difference, that is your answer.

Greg Benz says most images show no visible loss, even for large prints. In an earlier article, he says he would probably skip compressing your most important files. He also says to avoid compressing if you use Adobe's Super Resolution. Super Resolution on a lossy DNG can leave artifacts that would be visible in a large print. If you turn Super Resolution on before you convert, he says there is no concern. His write-up covers the method.

Squeeze does the same job with Adobe's free DNG Converter, and it leaves your originals alone until you decide. Get it at squeeze.photos/#install.