There is a high quality glass prism sitting in a south window of our living room. Every sunny day it casts a rich full rainbow spectrum on the wall across the room. Briefly, it shines in a dark place 30 feet away. The red–orange–yellow–green–blue–indigo–violet of that distant spectrum stretches 6 inches end-to-end. It is like a colorful clock passing time as it moves through the house.
Do different digital cameras see colors of the exact same object identically?
Today, I placed a sheet of white paper on the wall where the spectrum was to pass. I gathered my three cameras to get a photograph of the spectrum with each when it was on the white paper. All images were done at the same location and magnification as near as possible.
Each image was adjusted to set the surrounding dark area to black. No other adjustments were made.
The first two cameras show pronounced regions of red, green, and blue showing as distinct ovals. The third does not have those clearly defined ovals. Most consumer cameras use light sensors that convert light to electric charge called CCDs Charge Coupled Devices. A 3-colored filter of red, green, and blue is placed over the CCD to capture the components of color in the scene. If the neighboring pixels in the CCD all gather a lot of red, green, and blue, the location is rendered as white. If only red and green, then the location is yellow. Blue and green give cyan.
Most cameras have algorithms to compute the values of the neighboring locations on the CCD and blend them together into pleasing and accurate renditions of the colors of the scene. Some cameras are better at this than others. The first one above is better at that than the second one.
The third camera from the phone does the best job at this of the three. The image looks nearly identical to what my eyes saw. The blending is very smooth with no excessively bright regions. The colors are true.
Different digital cameras do not see colors of the exact same object identically.