When White Balance is adjusted in camera (so not in post-production, which I understand would leave artifacts if the image isn't raw or has any color compression) does it make any difference then in the final image when different lights are used if WB is adjusted?
For example, a scene lit entirely with Tungsten Lights which are 3200k, with a camera that is set to 3200k WB. If we take the same exact scene, and switch the bulbs for HMIs (5600k) and adjust the cameras white balance to 5600k, do these pictures look exactly alike?
jacklishufan
So if you save RAW file which record raw camera sensor values without any white balance/mapping to uint8(0-255), it is possible to adjust the white balance afterwards.
jacklishufan
To address orenazad's specific problem, the answer is probably not because temperature is an over simplications of the spectral distribution of light. For example, the sunlight have a more uniform distribution across all spectrums at 5000k while artificial lights are more "spiky". This may leads to subtle difference in the reflected intensity of certain specific colors.
Staffyirenng
@orenazad -- good question. They would look very similar after white balance correction as you describe, but there will likely be some color differences.
The way to see where the differences can come from is to think about the spectral power distribution of the light source and spectral reflectance functions of the materials. The SPD of the light reflected from objects is the product of these two functions. That reflected SPD is sensed by the R, G and B pixels in the camera.
Given a spectral reflectance function for an object in the scene, see if you can come up with two different illumination SPDs that can cause different R, G, B values after AWB normalization.
When White Balance is adjusted in camera (so not in post-production, which I understand would leave artifacts if the image isn't raw or has any color compression) does it make any difference then in the final image when different lights are used if WB is adjusted?
For example, a scene lit entirely with Tungsten Lights which are 3200k, with a camera that is set to 3200k WB. If we take the same exact scene, and switch the bulbs for HMIs (5600k) and adjust the cameras white balance to 5600k, do these pictures look exactly alike?
So if you save RAW file which record raw camera sensor values without any white balance/mapping to uint8(0-255), it is possible to adjust the white balance afterwards.
To address orenazad's specific problem, the answer is probably not because temperature is an over simplications of the spectral distribution of light. For example, the sunlight have a more uniform distribution across all spectrums at 5000k while artificial lights are more "spiky". This may leads to subtle difference in the reflected intensity of certain specific colors.
@orenazad -- good question. They would look very similar after white balance correction as you describe, but there will likely be some color differences.
The way to see where the differences can come from is to think about the spectral power distribution of the light source and spectral reflectance functions of the materials. The SPD of the light reflected from objects is the product of these two functions. That reflected SPD is sensed by the R, G and B pixels in the camera.
Given a spectral reflectance function for an object in the scene, see if you can come up with two different illumination SPDs that can cause different R, G, B values after AWB normalization.
@jacklishufan -- well put!