Thursday, January 8, 2009

RAW files - Are they really raw?

The way RAW files are output by the camera is of course a closely guarded trade secret for all the camera manufacturers. A RAW file by definition is the digital version (zeros and ones) of the analogue sample taken off the sensor. This happens without the application of a tone curve among other things. The idea there is so that one can "process" the RAW file anyway he or she likes, much like a digital negative which hasn't been developed. The good thing about RAW files is that you can process them in an infinite number of ways whereas with emulsion film negatives or positives (as in slides) you can only process them once. (of course I may be wrong, I never process emulsion film)

Here comes the problem.... Camera RAW files from certain manufacturers have been becoming more and more "processed" BEFORE they written to the card. To take a quote from an online forum, "Canon has been very, very good with this so far. Other brands have been notoriously deceptive about this. From Nikon clipping their black levels to "improve" noise performance, to Sony blatantly performing aggressive NR to their RAW files."

And this holds true in application. So much so that although Canon's EOS 50D RAW files contain more noise than the previous camera, I have found that with proper post-processing, one could properly handle noise and squeeze the maximum image quality out of the 15MP RAW images coming from the camera. So Chuck's comment that it all depends on the RAW processing technique and software being used hold true.

Tweaking my digital workflow has given me the opportunity to improve my post-processing skills too. After working with the RAW files of the EOS 50D and for that matter the RAW files of any camera, one gets a feel for the image characteristics for various types of images produced by each camera (e.g. bright vs dark, scenery vs portraits or landscape vs people), ISO (high vs low), flash or no flash etc. Hence I am able to post-process them appropriately to get the result I want.

After a while, you really know how to work with different cameras - both in capturing the best image and in post-processing so as to get the look you want or a consistent image regardless of what camera you use. This is what is most important as far as the science of photography goes.

Now back to the RAW-ness of RAW files, I think Canon has got it right this time. A RAW file should only have the bare necessities. Everything else which can be added later should be added later. To this end, shame on Nikon and more shame on Sony. They are corrupting the notion of RAW. In trying to compete with images leader Canon, they are going down a slippery path which hopefully other camera manufacturers do not follow. For now I'm very happy with the RAW files produced by my Canon cameras. Hooray for RAW.

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