Minhajul Haque

Digital Negative, The Archival Raw Format

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If you are a digital shooter who uses ACR or Lightroom I’m sure you have encountered DNG. You may be wondering what actually is it?, or what is it used for?, or why in the world should I convert my original raw image to a DNG developed by Adobe where it has its own vendor specific raw format? Because I rarely hear photographers talking about DNG which is very very important when it comes to image archiving.

What is DNG?

DNG is open and documented raw file format developed by Adobe. It’s open and its file spec is fully documented for programmers who want to build a DNG converter for reading DNG files without any special decoding. The main purpose of developing DNG is to ensure longevity to your raw files. Basically, it’s an archival format. I know this sounds wired. But it is. Let me tell you what Adobe means by longevity. The vendor specific raw file formats are undocumented and only they know what’s in the file. So you would be in real trouble if the vendor is not available after a few decades. So, your won’t be able to use those images kept in it’s proprietary raw format if your vendor be no longer in the business.

Reasons for Converting Images into DNG

  • It’s an archival raw format.
  • It’s lossless translation. So there is no risk of loosing original raw data that comes out of your camera.
  • Unlike proprietary raw formats it holds the metadata in the file itself. No sidecar XMP is created to hold the matadata. It ensures more security for your rights on your images and other legal or descriptive information about the images when you hand over your raw files to your clients (if needed); because sidecar XMP files that hold that metadata may be discarded by some systems when submitting those files over a network.
  • It embeds the thumbnail preview in the file which make it load faster in the system rather than generating preview thumbnails every time you use them.

Disclaimer: If you are using your proprietary Raw Converter, then DNG files are not read by those programs. Although some of them have started supporting DNG, you must be sure about it before converting your raw images into DNG. If you use only ACR or Lightroom for developing raw files and never uses those programs developed by the camera vendors then it’s absolutely fine to convert them into DNG. As the metadata and thumbnail previews get embedded into itself the size of the file also becomes a little larger.

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