Andrew - I'm just catching up on this thread and have found it interesting. Your response to Ben about white balance on the beach at sunset causes me to ask if there's some "native reference" or starting point for white balance. What happens when a white balance is made? I know what it attempts to do but I don't understand how it goes about it. Is there a null white balance or table of some sort or is there a common one assumed such as daylight and the new balance adjusts that? You're right that the cast would get screwed up if white balance is applied to the beach scene. Prints made from color neg film were all over the place with this kind of scene but some were actually pretty darn good. Was it strictly a difference in the creativity of the photographer and print maker or was there a technical approach that could be repeated with accuracy? This business about the illuminant must be central to colorimetric issues and it would be interesting to know more about it. It seems to me that when filters/sensors are designed there must be assumptions made that characterize the incoming light and this can't be gotten around when trying for colorimetric matches. I believe it would take a spectral approach for colorimetric matching but it wouldn't be possible to make a print that verified it. This would only be verifiable by the numbers - not visually. Well, that's what I believe anyhow. Ben - I read your statement differently I guess, and so my answer would be: the camera imposes an inherent error. The colorimetric problem starts there, in the camera. I don't know if a sensor or combination of filters can be made that would make a colorimetric match possible. On the other hand, they sometimes do a pretty good job of matching paint at the paint store. Henry Message: 7 Date: Sun, 02 Jun 2013 10:29:24 -0600 From: Andrew Rodney <andrew@digitaldog.net> To: "colorsync-users@lists.apple.com List" <colorsync-users@lists.apple.com> Subject: Re: RPP raw photo processor 64 Message-ID: <55224C4F-E1E0-4F46-A9E0-0507CE268C27@digitaldog.net> Content-Type: text/plain; charset=us-ascii <Snip> Ben:
Improper white balance and exposure are colorimetric failures
Andrew: Well it certainly isn't a recommend photographic workflow to improperly white balance and improperly expose! If I white balance a scene of a model on the beach at sunset, is that colorimetric failures? It would certainly produce an image that doesn't look anything like the original scene.