Make Lightroom Faster by Using DNG

Make Lightroom Faster by Using DNG

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Using DNG to Make Lightroom Faster

A question that often arises is how to make Lightroom faster. On my computer the biggest bottleneck comes when I’m looking at images in the Library module’s Loupe view or in the Develop module. Even images for which Lightroom has created 1:1 previews can take a few seconds to render properly. This may not sound much, but it’s annoying when flicking through images trying to decide which ones to process. It’s even more frustrating when zooming in 100% to check details which are important to me, such as that the eyes are in focus in portraits (above).

Luckily, there’s a relatively easy fix – and it doesn’t involve upgrading your computer or adding RAM (although those things may help). You can put it into action without spending money, and you should see a benefit regardless of how low- or high-spec your computer is.

Fast Load Data

The key is to convert your Raw files to the DNG format. You may not like the sound of it (I’ll explore some of the pros and cons later on the article) but it really does help. Why? It’s all to do with something called Fast Load Data – a partially processed preview of the image that enables Lightroom to render previews faster than it can from a non-DNG Raw file or a DNG file without Fast Load Data.

The net result of converting your Raw files to DNG and including Fast Load Data is that it enables Lightroom to rapidly display previews of your images. That means less time waiting and less frustration for you.

Converting to DNG

Using DNG to Make Lightroom Faster

The best time to convert your Raw files to DNG is when you import them from your camera’s memory card. To ensure you get the full benefit of using DNG, make sure you go to the File Handling tab in Preferences and tick the Embed Fast Load Data box (above). Do this before you convert any Raw files to DNG, otherwise you will miss out on the speed increase that DNG can give you.

These are the key steps to follow during the import:

Using DNG to Make Lightroom Faster

  • Select the Copy as DNG option in the Import window (above). This tells Lightroom to copy the Raw files from the memory card to the specified folder on your hard drive, converting them to DNG as it does so.

Using DNG to Make Lightroom Faster

  • Set Build Previews to 1:1 in the File Handling panel (above).

Using DNG to Make Lightroom Faster

  • After the import, go to the Catalog panel and select Previous Import. Then go to Library > Validate DNG files. Lightroom checks the files you have just imported and converted to DNG to ensure they are not corrupted. Any corrupted files are placed in a Temporary Collection that appears in the Catalog panel. I’ve yet to see a corrupted DNG file, so I don’t think it happens often.

Other Pros and Cons of DNG to Make Lightroom Faster

If you read around on the topic of DNG you will find that opinion varies widely as to whether it is good idea to convert your Raw files to the format.

Note that some Leica and Hasselblad cameras use the DNG format already – so if you are lucky enough to own one of those then the discussion is irrelevant. There’s also at least one Pentax camera that gives you the option of using either DNG or Pentax’s own Raw format (.PEF). If you own one, selecting DNG saves you having to do it at the import stage (if you choose to use DNG).

Bear in mind that camera generated DNG files don’t contain Fast Load Data – only DNG files created by Adobe software do so.

First, the case against using DNG:

  • It takes longer to convert your Raw files to DNG than it does to simply copy them. This is true – but as long as you’re happy to go away and do something else while your computer gets on with it, it won’t be much trouble. I often leave mine running overnight, especially if I have a lot of images to import and convert.
  • Not all applications open DNG. If you ever use, or think you may use, your camera maker’s proprietary Raw conversion software (such as Canon’s Digital Photo Professional) you should probably stick with your camera’s native Raw format, as the majority of these programs don’t recognise DNG. Check the documentation if you are unsure.

Using DNG in Lightroom

Using DNG purely to increase Lightroom’s speed is little use if you don’t use 1:1 previews. By default Lightroom discards 1:1 previews after 30 days (you can change that under the File Handling tab in Catalog settings), so even if you tell Lightroom to create 1:1 previews when you import your images, they will eventually be deleted by Lightroom. Not sure if an image has a 1:1 preview? Just select the image (or images) and go to Library > Previews > Build 1:1 Previews (above). Lightroom will build 1:1 previews for any selected images that don’t currently have them.

Now, some other benefits of DNG:

  • DNG files are smaller than other Raw formats. Converting your Raw files to DNG upon import reduces the amount of space they take up on your hard drive by up to 20 percent. That could be useful, especially for high volume shooters.
  • You may own a new camera with Raw files that aren’t recognised by your version of Lightroom or Adobe Camera Raw (ACR) if you are using Photoshop (not all readers will have upgraded to the latest versions). In this situation you can use Adobe’s free DNG Converter application to convert them to DNG. Adobe usually updates the DNG Converter to work with files from new cameras before Lightroom and ACR.
  • Embedded file verification. A DNG file contains a checksum that enables Lightroom to check if the original source data is corrupted. DNG is the only Raw file format that does so. It means that you can check your images after you have converted them to DNG to make sure there are no issues with corruption.

Mastering Lightroom Book One: The Library Module

Using DNG in Lightroom

My latest ebook Mastering Lightroom Book One: The Library Module is a complete guide to using Lightroom’s Library module to import, organise and search your photo files. You’ll learn how to tame your growing photo collection using Collections and Collection Sets, and how to save time so you can spend more time in the Develop module processing your photos.

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  • There is also another potential drawback: When working with RAW, the metadata modified by Lightroom are written into the sidecar XMP file, which is very tiny. On the other side, with DNG the metadata are written into the file itself.

    This may present few problems – it is more risky (though this is probably not really an issue), LR has to write much more data on disk and doing a perpetual backup is harder, because for any small change in keywords, you need to backup/copy/upload the much larger DNG and not only the small XMP (several hundreds times smaller) .

  • Good points. But the time lag of Lightroom previews have never bothered me much. I’d rather stick to RAW :).

  • This is something I might try for some of my larger photos which can be a pain to process. I assume Photoshop can handle DNG images right? For instance if I import 5 pictures for a panoramic as DNG files and then send them to Photoshop for stitching it’ll be able to handle it? I typically save the output image from Photoshop as a tiff file and then import the new file to Lightroom for final processing.

    Great read!

  • George Johnson

    Great article, I am big fan of DNG format. The various RAW formats won’t be supported forever so DNG at least should make them accessible for years to come. I do use DNG and you have to be careful how you store the original RAW data in the DNG, I made the wrong choice and found my DNGs were over twice the size of my source RAWs! Ooops! Try it, test it and find what works for you!

  • Notum

    Dont see any problem using raw for the untold future, if by any chance that day will come just have the latest software to handle old files problem solved, Way to many people try to use scare tactic when it comes to raw´s future, dng is a nice option but for people that want to use it dont delete your raw files thats all im saying.

  • Clipping Path

    Essential for every graphic designer

    Make Lightroom Faster by Using DNG
    Make Lightroom Faster by Using DNG
    Make Lightroom Faster by Using DNG

  • HiKlassPhotography

    After reading this I will give this a second look. Thanks

  • Shariq

    Does it become faster because of DNG, or because of using 1:1 previews?

  • Don

    I have the same question as another. Is it the DNG or the 1:1 or is it the combination of both? Since DNG files are about 20% smaller does that mean when opened in LR they are also using 20% RAM to do so? The article says it is faster without really stating why.

  • Don & Shariq: The combination of Fast Load Data and 1:1 previews is what gives the speed increase when you use DNG.

    John: It doesn’t matter whether you use DNG or your camera’s proprietary Raw format – either way Photoshop can handle it.

    Vit: Lightroom stores metadata in the Catalog, not the DNG file. Although you can set it to save the metadata within the DNG file as well if you want.

  • Clay

    I would like to respectfully disagree with you.

    You have described two entirely different processes – DNG and 1:1 previews.

    I convert all my RAW files to DNG during import and I don’t believe you’ll get any noticeable speed difference when using DNG as stated in the title of this post.

    The speed improvement you say is the result of using DNG is actually the result of creating the 1:1 previews during import. However that will take a lot of time at import for photos you may never view at 1:1. LR will happily make 1:1 previews of RAW files as well with the same increase in speed.

    I convert my RAW files to DNG during import and let LR create standard previews. Why create 1:1 previews when they are only used when zooming in on a photo, not while flipping through them, unless you view at 1:1?

    I let LR create the 1:1 previews when I need them.

    Also 1:1 previews take a lot of hard drive space so on a slow or nearly full hard drive, having 1:1 previews may actually slow LR down in extreme cases.

    Here is a link to Adobe’s web page on Optimizing Lightroom with a good explanation on the different previews available.

    http://helpx.adobe.com/lightroom/kb/optimize-performance-lightroom.html

  • JeanLuc LaBarre

    Andrew, how ever can I thank you for such a tip?
    It’s a total game changer!
    Thanks.!.!

  • Hi Clay, if you Google ‘fast load data’ you will find plenty of articles explaining what it is. Here’s a quote:

    “Fast-load data,” a miniature raw preview image embedded in the file
    that makes it faster to switch among images in Lightroom’s develop
    module–eight times as fast, according to Tom Hogarty, principal product
    manager for Lightroom.

    This is the full article:

    http://news.cnet.com/8301-30685_3-57371809-264/adobe-offering-new-reasons-to-get-dng-religion/

    Hope that helps clear things up.

  • ML

    When I tried converting my images to DNG, I found that they were about 10MB bigger than my RAW files. I did not have the “embed raw file” box checked – is there something I’m doing wrong?

  • Skeeter

    I honestly don’t know why Lightroom is soooooo friggin’ slow. I use both ACDSee and Lightroom. Lightroom definitely has superior editing abilities, but I can flip through 30 files on ACDSee by the time I load 1 or 2 in Lightroom. If only the two could merge 🙂

  • Hi Skeeter, sounds like something to do with Lightroom’s previews. I wrote an article about speeding up Lightroom on my website, you can read it here. It should help:

    http://www.andrewsgibson.com/blog/2014/06/improve-speed-performance-lightroom/

  • Skeeter

    Thanks for the link. I’m actually familiar with most of these settings (except that I’ve only just started using dng). Have you used ACDSee? Scrolling through thousands of thumbs with ACDSee is as fast as scrolling through txt….lighting speed, unlike LR. My LR is fairly well optimized and my computer is fast — and I keep doing stuff like adding SSD drives, more memb, etc., just to increase the speed….but LR is still way slow.

  • I haven’t used ACDSee, but I’ve heard good things about it.

  • Skeeter

    All of the things LR does poorly, ACDSee does extraordinarily well…..but all the things that LR does well, ACDSee is kinda clunky haha. They need to join forces and fight evil.

  • affinityseattle

    There’s still a bit of conflation and the article needs to be amended. Building a 1:1 preview jpg cache is ONLY useful in the Library module. When you step into Develope, you are pulling the RAW file and building a fresh 1:1… every single time. I’ve argued with the devs on this and even spoken to Tom in person. It’s just their view that a fresh preview is necessary. As you have stated correctly in this comment thread, the DNG fastload essentially allows LR to break the image into tiles and utilize multiple cores to render the 1:1 on the fly. So, your article is a bit wrong that DNG only benefits people that use 1:1. The correct answer is that DNG speeds up everyone using the Develop module if they have a multi-core system because you are always creating a 1:1 as you step through there. To significantly speed up your workflow, the real solution is to always build your 1:1 jpg cache and filter your shots in the Library module ONLY.

    And FWIT, I have a raw library over 300k shots. Most are now DNG and I have literally hundreds of corrupted DNG files scattered about over the many years.

  • Rob

    Is there a way to embed jpg into the DNG after import? Using large files (36mp)
    my pretty fast computer still is very slow with loading the files.

  • Hi Rob, are you referring to Fast Load Data? There’s no way of adding it to the DNG file after import. I usually leave my computer on overnight to import and convert files to DNG if there is a large number to process.

  • Mark

    sounds very useful, will try this

  • MaltaU571

    I see no use of converting to dng on import. If say I have 500 pics which I have to cull down to maybee 150 or 200 it`s a waste of time. I only convert to dng at the end of the job after the edits,export and other stuff

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  • Spy Black

    I just ran across this article, and I’d liek to add that I’ve read somewhere that DNG files use lossy compression, so they are the RAW equivalent of JPEG files. While lossy compression is great for a final JPEG output, the last I want my rae data storage files to have is discarded, potentially valuable data.

  • There are two types of DNG files, lossless and lossy. Lossless DNGs aren’t compressed, but lossy ones are. You’re right, there’s no point in converting your original Raw files to lossy DNGs. But lossless DNG’s will be fine. This article explains it in detail:

    http://lightroomsolutions.com/full-blooded-and-lossy-dngs/

  • clemens

    hey clay,
    you wrote: “Why create 1:1 previews when they are only used when zooming in on a
    photo, not while flipping through them, unless you view at 1:1?”
    but isn’t this a very crucial thing? the 100% view of an image before developing it?
    if you take a some shots of the same motive you have to check the 100% to see whats your best shot. the point of the sharpness, the grain. if its moved.
    especially for action-shots.
    so i realised that – if you really wanna choose your best shots – you’ll end up in checking at least half of your photos at 100%.
    so yeah. load all at 1:1!
    that’s my opinion.
    but maybe that differs from photographer to photographer. maybe some don’t really need the full view of every pixel.
    cheers,
    clemens 🙂

  • Mandy Baldwin

    I am so not techno. I have a Fuji xt1 can I load that straight into Lightroom? I currently use Adobe DNG Converter for the RAF files.

  • Ghumu

    turn off the “Embed Original Raw File” option…
    I mean, if you did’t fix it in the past 2 years 🙂

  • Oscar Jonsson

    That’s exactly what he said he did not have checked…?

  • Hi Mandy, yes you can. No need to use Adobe DNG converter.

Some Older Comments

  • Josh October 3, 2013 12:14 am

    This is something I might try for some of my larger photos which can be a pain to process. I assume Photoshop can handle DNG images right? For instance if I import 5 pictures for a panoramic as DNG files and then send them to Photoshop for stitching it'll be able to handle it? I typically save the output image from Photoshop as a tiff file and then import the new file to Lightroom for final processing.

    Great read!

  • Juan Castillo October 2, 2013 10:46 pm

    Good points. But the time lag of Lightroom previews have never bothered me much. I'd rather stick to RAW :).

  • Vit Kovalcik October 2, 2013 04:39 pm

    There is also another potential drawback: When working with RAW, the metadata modified by Lightroom are written into the sidecar XMP file, which is very tiny. On the other side, with DNG the metadata are written into the file itself.

    This may present few problems - it is more risky (though this is probably not really an issue), LR has to write much more data on disk and doing a perpetual backup is harder, because for any small change in keywords, you need to backup/copy/upload the much larger DNG and not only the small XMP (several hundreds times smaller) .

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