Sunday, 29 May 2011

A wet Sunday and reflecting on technical RAW image quality

Here's a response I posted on at a DPR forum:


I was looking at the reviews on dpr and wanted to know about RAW image quality.  All other things being equal is RAW image quality the most important?  I mean isn't that the "real" picture?


The most important, in no real rank sequence are:

  • The shooter - at least 80% of the picture. I have repeatedly seen Grumpy Old Conservatives (sometimes I am one of them) proclaim that gear A is so bad that it could not be used for activity X and then wait a few months, look around and voila, some unknown person on the other side of the internet produces an image which is spectacular.
  • The ability of the shooter and camera to get exposure "right". Some people rely on the camera a lot, others rely on themselves a lot. Those who rely on the camera need the exposure to be "just right"
  • The ability of the shooter and the camera to get the focus "right". Again some people rely a lot on the camera, others are more tolerant
  • For their needs, some shooters rely on the in-camera JPEG engine to get it right. They have no patience or persistence to sit at the computer and process data, their skill is in the field - composing, choosing the "decisive moment" - you can get gear that is technically perfect (i.e. 99% better digital quality vs 80% digital quality) but the image sucks because the shooter is a dud and gets composition, focus, exposure, depth of field or the moment, wrong.
  • RAW quality is technical quality - in order to render on the screen, a human or a program has to initially preset the choice of gamma transformation curve, colour saturation, sharpening, aberration correction, perspective correction. Any image you see on the screen that is recognisable to a human, has been rendered with these rendering parameters - the rendering is not about technical perfection it is about visual choice - the two do not have to be equal.
  • The RAW quality is the sensor and image processing pipeline quality - if you pick a camera which does not have the lens you want to use or the lens quality that you want, then the image could suck.

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