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Well, without knowing the light source, it's impossible to accurately measure color. They mention applying white balancing to fix it, but this makes an assumpt
by cafebeen 12y ago
Well, without knowing the light source, it's impossible to accurately measure color. They mention applying white balancing to fix it, but this makes an assumption of some characteristic light source:
http://www.cambridgeincolour.com/tutorials/white-balance.htm http://www.cambridgeincolour.com/tutorials/white-balance.htm
Beyond that, there is processing done by the sensor, the photo app, the person who put it online, etc...
- jacobolus 12y agoThat’s not quite it. More precisely, it’s always impossible to measure “color”, because color is a perception in the brain, not a physical fact about the environment. But it’s certainly possible to make a good guess at the light source by looking at objects in the scene. In this particular case, we can look at the black and white dress at bottom left, which we can reasonably expect will appear neutral to human eyes and most “properly white balanced” camera images. I’ll agree that the camera used here has a relatively crummy sensor / processing pipeline though.
- BillinghamJ 12y agoA human can't measure color, but you're measuring something when you count the number of photons coming through a filter.
- cafebeen 12y agoYes, but the spectrum of the light hitting the eye is a physical thing. The physical problem is that multiple environments can make the same spectrum, e.g. is it a bluish light source & white dress or white light and bluish dress. White balancing can fix this if you know the light source, e.g. the sun, but that's either an assumption or something calibrated separately from the image. That said, the perceptual issues are certainly a problem as well :)