DNG vs proprietary RAW formats

In this episode, I explain to you what DNG is and share the pros and cons of using it over your proprietary RAW format.

What is/means DNG?

DNG stands for Digital Negative and is an open lossless RAW format. In 2004 Adobe created this format based on the TIFF format which Adobe had also created in 2001. While it can be considered as a proprietary format, Adobe released a license so the DNG format could be fully exploited by anyone royalty free. The DNG specifications are publicly available.

Why another RAW format?

DNG was Adobe’s response to the lack of standardisation of RAW format. Basically, all camera manufacturer have created their own proprietary RAW, with its own specifications which make the format not fully usable by all 3rd party software. Canon has CR2, Nikon NEF, Pentax Pef etc.

Where does DNG intervene in one’s photography workflow?

Firstly, it is worth noting that several camera manufacturers have embraced the DNG format as their native RAW format, produced by some of their cameras: Hasselblad, Leica, Casio, Ricoh, Pentax, Samsung… There are basically 2 ways of generating a DNG:

1. The camera does it
2. The 3rd party software like Adobe Lightroom, Adobe Photoshop, Adobe DNG Converter, Apple Aperture, Google’s applications… offers the conversion functionality upon import of your photographs or later.

How to convert your camera RAW files to DNG in Lightroom?

You start from the usual import panel:

Then you select as below:

Choose the usual location options:

And Lightroom will then convert your camera RAW file into a DNG file and place it in the chosen destination folder.

DNG – Lightroom’s favourite file format

There are many reasons which make DNG the undeniable favourite file format for Adobe Lightroom:

Embed Fast Load Data

The Lightroom users are familiar with the preview concept. One can define in Lightroom the size of the photo preview Lightroom generates to show your the photograph in the library module. This is often something set up during the import of the photographs into Lightroom:

This is preview is then created and kept as long as it is defined in the Lightroom catalog settings:

The Preview can take quite some space on your system disk:

When opening one photograph using the 1:1 ration in the Library or Develop module, Lightroom can take a couple of second to generate the preview. There is an option only found in Lightroom Preferences called Embed Load Data is enabled which once enabled will load the preview inside the DNG so Lightroom can pull it quicker than reading from the preview catalogue.

Validate DNG files

After the import, go to the Catalog panel and selectPrevious Import. Then go toLibrary > 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.

Bye Bye XMP

In May 2013 I explained what the XMP file was. Well when using DNG in Lightroom, the need for XMP is no more which simplifies the storage and backup of your photographs. All the modifications (Metadata, development) made to the photograph in Lightroom (or in CameraRaw) are stored inside the DNG file. This means one can share with someone a DNG file, keeping all the RAW quality image information with on top all the development and metadata changes made.

Pros & cons of covering native RAW to DNG

Pros:

• Space saver: DNG natively contains the photo information compressed losslessly which means the photo information forms the initial RAW file is not altered during the conversion to DNG, and unlike the native RAW format, that photo information is compressed which means your resulting DNG file is around 20% smaller in size than your RAW file. While this might seem not much, think again if you are an enthusiast photographer with tens of thousands photographs stored on your computer disk(s).
• More Usable: DNG specifications are publicly available and exploitable which makes DNG more universal than the camera manufacturers’ own RAW format. As a resulting, more 3rd party tools can read DNG (including DXO) just like any JPEG. Please note that if you are a Windows 7-8 users you may need to install the Adobe DNG codec to see the image preview as the DNG file icon.
• Future proof: With each new camera model, 3rd party softwares need to update their code/libraries to work with the new camera model’s RAW format specificities. This sometimes means the RAW file of your new shiny camera cannot be read by your favourite editing software for months. It could also mean that it would require you to buy an upgrade of your software (i.e. this was the case for Photoshop before the Creative Cloud version). Adobe ‘s free DNG converter is maintained faster than editing software which means that by converting your native RAW into DNG you can carry on using your development workflow. Also updating editing tools with new libraries means the software is growing over time. It is common practice for software editors to stop supporting the old version of format/files. If you had one of the earliest Digital cameras, chances are you are not able to open your RAW files in today’s software. Given the software gets updated according to the Operating System, you may not even be able to run the old software which recognised that old RAW format of your old camera. Should your photographs be converted into DNG, then there would never be any issue to open them today (or in the future) since the DNG structure is always backwards compatible.
• Keep your Native RAW: As seen in the Lightroom preference screenshot above, if one is worried about losing the initial native RAW file, it can be included in the DNG during the conversion.
• Universal RAW format in constant improvement: Adobe continues to work on the DNG format, enhancing it year after year and adding more functionality and features.
• Bye Bye XMP: DNG eliminate the need for XMP sidecar file which means you can share your RAW file (DNG) with anyone and that person would see the development changes you have made in a non-destructive way.
• Speed up Lightroom: DNG offer Embed Fast Load Data option.
• More Metadata: One can add as much more metadata information in a DNG.
• Native format for all Adobe: All Adobe creative imaging products recognise the DNG format. So whether you use Premiere Pro or Illustrator, you can use the same file across avoiding the pain of conversion.

Cons:

• Not recognised by camera manufacturers’ software: DNG is not recognised by camera manufacturers’ editing software such as Canon Digital Photograph Professional and Nikon Capture NX.
• Loss of some camera metadata: DNG strips out some of the unrecognised metadata (such as Active D-Lighting, focus point selected, Picture Control/style [i.e monochrome]) from RAW files, making it impossible to retrieve this data from DNG in the future. Not true anymore
• Extra time consuming: The conversion from the native RAW format add some extra time in the post production workflow.
• Bigger file: Bear with me as I am not contradicting myself. It seems that in some photography contests, a RAW file is requested from the artist. DNG are not always considered as Native RAW file. So to not lose the opportunity to participate to such contest, you may want to embed the native RAW file inside the DNG as shown in the screenshot above. This will obviously increase the file size, and you would end up with a DNG file bigger than your initial native RAW file.
• Contest: Some Photography contests seem to be requiring to upload you native RAW file.

My conclusion

For those who have been following me for a while, you may think that being an Adobian, I am bound to be a strong advocate of DNG from day one in 2004. Well, not true. I came very late to DNG, and in fact, it was last December after a discussion with a colleague of mine who is an evangelist for Adobe Creative products. So why made me jump ship? It is a combination of all the pros I listed above and the fact that my photography workflow relies on Adobe Lightroom and Photoshop. I am not using Canon DPP, and after my recent dive in the tool for the purpose of my videos on the Noise and its reduction process, I am even more convince of the goofiness of the tool. Maybe the strongest pro that led me to choose to convert all my native RAW files (several thousand) to DNG is not having to rely on XMP files. As many photographers, I have a fear of losing my work. Hence I have covered the topic of backup several times in my episodes. Not having to worry about safe keeping not only my RAW files but the XMP sidecar is a bonus. Then the 20% space saving of all my photographs is a bonus. Another bonus is the safe keeping of Lightroom’s virtual copies which I will cover in an upcoming episode. So you might be wondering whether I embed my native RAW in my DNG and the answer is no. Why would I? I honestly do not care much for the camera’s specific metadata such as the focus point selected… Regarding the jpg preview size I chose in the Lightroom Preferences I use the medium jpg so keep the file size low. If you enjoyed this article, please share it with your friends using the Facebook, Pinterest, Google+ and twitter buttons.