I just saved a gig of HD space in ~90 seconds

…without losing any files or visual quality. 1.5GB of storage is now down to 500MB.

  • In Lightroom select some raw files.
  • Select Library->Convert to DNG.
  • Choose “lossy” compression.
  • Choose to delete the originals (scary sounding, but it shouldn’t be).

Honestly I’m thinking the misleading “lossy” option should be called “visually lossless,” because as I demonstrated the other day, there’s almost zero chance you’ll ever be able to perceive a difference between this & the lossless compression option. (You’d have to crank up a very dark photo by more than 4 exposure stops.)

Pass it on.

7 thoughts on “I just saved a gig of HD space in ~90 seconds

  1. I’ve come to this conclusion a while back.

    If only the lossy option was an option on import!?!

    Any chance you can sneak a JDI request back into your old teams? 🙂

    [Tried it while I was there! I recommend bribing Tom/Sharad. —J.]

  2. At $150 for a 4T hard drive, that works out to a savings of about … four cents.

    [Think a little broader/newer: The savings is massively important when you’re talking about mobile workflows, where on-device storage is limited & bandwidth is even more so. That’s why Adobe uses this approach to enable Lightroom mobile sync.

    Here’s a better way I could have put it: “I just tripled my upload speed & let myself store 3x the raw files on my tablet.” And yes, developers haven’t yet made raw/mobile workflows really smooth—yet. —J.]

  3. Are you kidding me? What a stupid suggestion. Just because it’s not visible to you and your workflow does not mean it’s not visible.

    [I demonstrated in the other post exactly where differences are & are not visible. —J.]

    Of course, if you’re interested in optimal quality from your raws, you probably won’t be using LightRoom. Remember folks, this advice is from John Nack – maybe the worst product manager in Photoshop’s history.

    [WTF…? Who are you, and what the hell did I ever do to you? —J.]

  4. wouldnt lossless compression offer better corrective editing latitude, whether a few deep edits or a chain of little ones? sort of like having more bit-depth in audio/photo/video masters? unless this ‘lossy raw compression’ is some form of log-from-linear?

  5. Great tip, I did it to my older files last year and saved multiple Gigs on my old laptop. But, there is a major downside. I’ve yet to find any non-Adobe tool that can read a Lossy DNG file (and that includes Apple’s raw library that so many third party OS X tools rely on).

    [That’s a good point, but there’s nothing blocking developers (including Google) from adding support. I would never advocate a solution that locked me or anyone else into a proprietary path. —J.]

  6. It occurs to me that Lossy DNG is actually pretty inefficient (despite having converted my archive to lossy DNG).

    A 24MP raw file hosts 16M green pixels, 8M red and 8M blue; while a Lossy DNG has three channels of 24MP each. 2/3 of the information in a Lossy DNG is interpolated.

    I wonder if this impacts noise reduction performance. Does Lightroom apply noise reduction on a subpixel level, or is it only done after demosaicing? In the former case, NR performance might well be better on a raw or lossless DNG file; in the latter case there should be no difference.

    Also, props on leaving up Figen’s rude and unnecessary comment when you’d have been fully justified to trash it.

    – Nico

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