RAW vs. DNG

If you read my previous entry on working with RAW photos in Photoshop CS you would have seen that I used several apps for importing, color correcting my digital negatives. I have been using Photoshop CS2 now for a few months and have really come to love the new RAW capabilities that it offers. Before we go into my new workflow for working with RAW images (in my next entry), I want to outline some of the technology and define some of the terms relating to RAW photography and Adobe's (relatively) new format: DNG .

Current RAW Formats

If you aren't aware, most new high-end digital cameras give you one of two options for capturing images: you can capture in a compressed preprocessed format like JPEG, or you can capture the RAW image sensor data. All camera manufacturers refer to the later as simply "RAW" but each use a different method for storing the data. Each of the manufacturers base their format on the TIFF image type, but each include sensor and EXIF data, and White Balance information in their own proprietary ways. Canon uses CRW and CR2, while Nikon uses NEF files, Kodak uses the DCR format (and others use different formats.)

This lack of standard is what really hampers the adoption of the RAW format by mainstream image processors. Moreover, because these methods are proprietary, they cannot ever be modified by 3rd party applications. While programs like Adobe Photoshop allow you to make changes to the exposure, white balance, and other settings you cannot set those as "defaults" for that given file. Photoshop has gone around this limitation by creating separate sidecar files (.xmp) that store all this data. This redundancy is more than a nuisance - it also doubles the amount of files stored on your computer - and heaven forbid you should ever lose one of those sidecar files (or simply separate them from your RAW images).

Adobe DNG

Along comes Adobe and their open format: DNG. The DNG format is Adobe's effort to create an open standard for RAW images. Similar to what the PDF format did for documents, Adobe has made this an open document format for camera makers and image editors to store RAW camera sensor data. The world of web design can attest that standards are a good thing: creating standardized file formats and methods will help all camera makers and image editors leverage the benefits of shooting in RAW.

As you can probably gather from my remarks, I am really excited about the DNG format. Not only does it reduce clutter (by removing the need for sidecar files), but Adobe also managed to compress the RAW data in a lossless format. This compression makes storing your RAW 'negatives' take even less space (which when you shoot a lot of pictures is a very good thing). Moreover when you convert your proprietary RAW images to open DNG images, you are given the option to embed the full proprietary RAW image inside the DNG file. While this is a good idea in theory, there are no real reasons to keep a duplicate, because DNG format keeps 100% of the RAW sensor image data.

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