A few weeks ago, I finally took the plunge and converted my entire raw image archive to DNG. This wasn’t a trivial decision to take given the sheer volume of images that are in the archive now but with iView MediaPro 3 supporting XMP information in DNG files, it seemed like the time had come.

Why convert to DNG?

  • The obvious reason is to allow metadata for the images to be stored in the files without having to resort to using things like Apple resource forks or sidecar files. I’ve always been careful about not synchronizing metadata back to my raw images (treating them as read-only) which makes me more dependent on iView MediaPro than I’d prefer. As DNG files are really just slightly fancy TIFF images, the mechanism for writing back the XMP-encoded metadata is pretty well understood and robust.
  • I have a plethora of raw image types. I’ve got CRW/THM from a Canon D60, raw “TIF” files from a Canon 1D and CR2 files from Canon 1DII and 20D cameras. It’d be helpful to have a common format for all my raw images in order to simplify how to export metadata to them.
  • Better previews. This is a huge plus if your workflow includes Adobe Bridge, Photoshop CS2 and iView MediaPro 3. The Adobe Raw Convertor will regenerate previews for a DNG file if parameters, such as the white balance or exposure, are changed. It also generates previews based on crop or rotation parameters. This means that the iView MediaPro shows previews that reflect the current conversion and not just the parameters that were recorded when the raw image was taken. The result is a raw image catalog that looks a lot closer to the finished product.
  • There’s definitely some future-proofing value in using DNG to store a vanilla, slightly-less proprietary version of my image data. I’m still archiving the basic raw images but it’s out of sheer paranoia rather than some lack of belief in DNG’s future.

The conversion into DNG was really very straightforward. A definite tip of the hat to the folks at Adobe who worked on the DNG Convertor application that’s provided as part of the ACR support. It’s not the fastest convertor I’ve ever used but it did one thing that completely won me over. It’s smart enough to traverse a directory hierarchy and build a mirror of that heirarchy using DNG files. Yeah! I feared I’d have to spend a day writing scripts to move the shiny new DNG files back into the right place. As it was, I just had to spend a day waiting for the DNG conversions to finish.

As for conversion parameters, I’ve gone with

  • Medium sized JPEG previews
  • Lossless compression
  • Preserve Raw Image (i.e. no de-mosaicing)
  • Embedded originals

The last option is one that I wrestled with but I finally decided to just bundle the raw images into the DNG files too. Why? Well, it keeps everything in one place and disk space is cheap these days. Out of paranoia, I also archive my raw files separately. Can’t be too careful…

I haven’t found any real downsides so far using my current workflow. My DNG images contain the correct and current metadata for them and I can see that information in Bridge and Photoshop CS2 without any problems. There’s really no difference to working with CR2 files except that I’m not generating XMP sidecar files for the raw conversion parameters now.

And that can only be a good thing.

One Response to “DNG”

  1. Chris says:

    Have you discounted the use of Apple’s Aperture? I don’t have as many images as you, nor are they of such high quality, but it is very convenient to use. iView is on my machine as well, but it is ever so slooow.


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