Hi Nathan -- I was hoping someone much more informed than me would weigh in with some engineering truth. All I got on offer is the thin gruel of observation.
Mr Endo wrote:
So, my questions:
- Does anyone have a camera to whose RAW files Aperture does not apply in-camera white balance settings?
- Does everyone else agree that this exception to "RAW is RAW" is acceptable?
1. I don't. RAW is sensor data. Most cameras record the White Balance camera setting as a metadata tag attached to the RAW data (The WB has no effect at all on the captured data.) Most RAW converters use this setting as the default WB. Some RAW converters perform "colorimetric interpretation" -- they basically compare the data captured to a generic color space and assign a WB. (This is, I assume, the same thing a camera set to "Auto WB" does. My camera is superb at assigning a WB for any mixed scene; it's repeatably bad, though, whenever the actual scene is truly colored (meaning "away from average").) In both cases -- 1. using the attached-to-the-RAW-data WB, and 2. analyzing the captured data to intelligently predict the WB -- a WB is applied to the RAW data. It has to be, in order to produce an image from the data.
2. The problem here isn't that this is an exception -- it's that different people mean different things when they say "RAW". The RAW data is RAW data. As above, the WB setting has no effect on it. But the image derived from the data -- any image produced from the data -- much have a WB set (and, for human use, a tone-curve applied). Some people mistaken think that RAW is an image format, or that the image produced by the RAW converter is a "RAW" image. It is not. RAW data must be converted to an image format in order to be displayed as an image. The conversion must apply a WB.
I have found it useful (though perhaps mistaken) to conceive of my data-gathering to picture-making as following these steps:
. Capture a pattern of light. This is just data.
. Convert the data to an image. RAW conversion done by Aperture. (NB: the settings for this can be changed.)
. Adjust the image to my artistic satisfaction
. Convert the adjusted image to an image format file
. Publish the image-format file in one or two now standard forms: to be viewed on a computer monitor, or as a print.
I mention only because at some point I consciously added the "Convert data to image" step in order to better grasp the process. RAW data is RAW data -- but that step identifies an intermediate that many overlook. At that step the information recorded along with the RAW data and stored in the RAW file is applied to the RAW data.
To me, "RAW is RAW" is correct. "Aperture will not apply any camera settings," is wrong.
I am happy for any clarifications or corrections.
Often the in-camera white balance setting is not easily readable by Aperture. In that case, Aperture must make a best guess, which might not be correct. In Canon's case, there is so much information about their white balance setting, that Aperture might be able to make a better setting to match your wishes.
The point of Raw is Raw is that even if Aperture totally screws up its initial WB, any adjustment you make is totally lossless and does not affect what change you can make after the fact. For a JPEG, some information is lost during the conversion, and that may affect the range of white balance adjustment you can do after the fact.