Working Without White Balance

Question

Camera: Nikon D90
Adobe CS5 Design Suite
My goal is to work in Photoshop and Camera Raw without using White Balance.
As I understand, the camera stores within the raw NEF file what was seen by the camera chip without correction. For example, if the camera chip sees say 10,000 red photons, this is stored as say 200. If the camera chip sees 20,000 red photons, this is stored as 400. Hence, it is linear. Of course, the actual storage is as a Bayer array.
http://www.cambridgeincolour.com/tutorials/camera-sensors.htm
In theory, from the raw NEF file, one should be able to reconstruct the image that fell upon the camera chip.
On the camera itself, there are many camera White Balance settings. However, it lacks a "None" i.e. "As Is" setting meaning do not assume anything about the light source and make no correctons. Just record the photon levels and give me back the same image that was focused on the camera chip.
As an experiment, I shot a daylight scene using 2,500K (obviously, an extreme value) for the white balance. When I look at the raw file in Camera Raw, the "As Shot" shows a heavy blue tint. Hence, Camera Raw was using the  2,500K white balance selecting of the Nikon for the "As Shot" setting in Camera Raw. Looking at the Camera Raw basic panel White Balance drop down  items, there is no "None". Hence, Camera Raw always assumes there is a White Balance and makes corrections.
Why would I want to do this? For example, I have multiple varied color light sources. I want to see exactly the image my eye sees. I do not want the camera making corrections since there is not a single light source for it to make assumptions about how to correct.
Is there a way in Photoshop or Camera Raw to show me the image without any white balance correction. Thanks in advance.

Answer 1

Petrula wrote:
Camera: Nikon D90
Adobe CS5 Design Suite
My goal is to work in Photoshop and Camera Raw without using White Balance.
As I understand, the camera stores within the raw NEF file what was seen by the camera chip without correction. For example, if the camera chip sees say 10,000 red photons, this is stored as say 200. If the camera chip sees 20,000 red photons, this is stored as 400. Hence, it is linear. Of course, the actual storage is as a Bayer array. In theory, from the raw NEF file, one should be able to reconstruct the image that fell upon the camera chip.
On the camera itself, there are many camera White Balance settings. However, it lacks a "None" i.e. "As Is" setting meaning do not assume anything about the light source and make no correctons. Just record the photon levels and give me back the same image that was focused on the camera chip.
The sensor is linear, but the sensitivities of the red, green and blue channels differ, so one must take these differing sensitivities into account when rendering the image from the raw data. As demonstrated by others, channel multipliers of unity (UniWB) do not yield the intended result. To obtain your intended result, empirically determined multipliers would be necessary. When used for white balance, these multipliers are chosen to that a white target will have equal RGB values in the rendered image. For your purpose, multipliers would need to be chosen so that the white target would assume the color of the incident light. In other words, if the white target were illuminated with reddish light, the image would be reddish and not white.
Why would I want to do this? For example, I have multiple varied color light sources. I want to see exactly the image my eye sees. I do not want the camera making corrections since there is not a single light source for it to make assumptions about how to correct.
Is there a way in Photoshop or Camera Raw to show me the image without any white balance correction. Thanks in advance.
On the camera itself, there are many camera White Balance settings. However, it lacks a "None" i.e. "As Is" setting meaning do not assume anything about the light source and make no correctons. Just record the photon levels and give me back the same image that was focused on the camera chip.
As an experiment, I shot a daylight scene using 2,500K (obviously, an extreme value) for the white balance. When I look at the raw file in Camera Raw, the "As Shot" shows a heavy blue tint. Hence, Camera Raw was using the  2,500K white balance selecting of the Nikon for the "As Shot" setting in Camera Raw. Looking at the Camera Raw basic panel White Balance drop down  items, there is no "None". Hence, Camera Raw always assumes there is a White Balance and makes corrections.
Why would I want to do this? For example, I have multiple varied color light sources. I want to see exactly the image my eye sees. I do not want the camera making corrections since there is not a single light source for it to make assumptions about how to correct.
Is there a way in Photoshop or Camera Raw to show me the image without any white balance correction. Thanks in advance.
I infer that you want the captured image to reflect the spectra of the actual scene luminances (or more likely a metameric tristimulus match) rather than how you perceive them. The human visual apparatus exhibits chromatic adaption, whereas the sensor does not. The CIE xyz model assumes complete chromatic adaption and the color models based on CIE models need a white point to operate, so you are attempting to use ACR in a manner other than for which it was intended. There is an interesting exercise on the Stanford web site that shows how one can use a digital camera (the Nikon D70) in conjunction with a spectrophotometer to obtain spectrophotometric data from the camera. To recreate the actual spectra, two additional colored filters are required, but if one merely needs a metameric tristimulus match, perhaps only the three native CFA filters of the camera would be needed.
http://scien.stanford.edu/pages/labsite/2006/psych221/projects/06/clintonk/index.htm
Going back to ACR, experience indicates that if one wants to recreate the appearance of a colorful sunset or a candlelit scene (cases that exceed the limits of chromatic adaption), a daylight color balance works best. It would seem intuitively that an equal energy illuminant (CIE Illuminant E) would be appropriate. This corresponds to a correlated color temperature of approximately 5455K.
http://en.wikipedia.org/wiki/Standard_illuminant