RGB is an additive color scale that was created to represent colors on digital devices. RGB uses 0 to different colors of light to create different colors.
RGB color scales were created to display colors through pixel digitization, where a Red, Green and Blue phosphor are grouped together. This is what you are seeing when you are looking at your computer, TV, or phone screen. Have you ever walked into Best Buy or Target and seen the rows of televisions all playing the same football game? As your eyes pan over the TV screens you might notice that some TVs look more washed out than others. One TV has bright neon grass, and the one next to it looks almost gray in comparison.
Now the TV pans to the referee. You are now seeing a bunch of different skin tones on the same referee. He appears to be pink on one screen, orange on the other, and pale on the next one.
This is because different television manufacturers all use different display phosphors. CIE XYZ represents color through a mathematical table that weighs our retinal response to wavelengths in a range.
CIE Tristimulus scales are highly precise and can represent color to a second decimal place. This means that not only can many more colors can be represented with this color scale, but they are also more exact. Again, using our GPS analogy, they provide an exact color address vs. Color is not a primary physical quality, it is a psychophysical quantity.
This is why there needs to be a common color language to give a representation of color in an exact and precise way. In order for humans to perceive color, three things must be present. First, you need an object, then you need a light source, and lastly someone to observe the object. Humans perceive color by gathering information from the wavelengths emitted by the light reflected off an object and then make a subjective statement about the color.
The human visual system is more sensitive to changes in luminance than to changes in hue or saturation, and thus a wider bandwidth should be dedicated to luminance than to color information. Y is similar to perceived luminance, I and Q carry color information and some luminance information.
The Y signal usually has 4. Originally, the I and Q had different bandwidths 1. These transforms involve tristimulus values , that is a set of three linear-light components that conform to the CIE color-matching functions. In XYZ, any color is represented as a set of positive values. The range for valid R, G, B values is [0,1].
Note, this matrix has negative coefficients. This means that not all visible colors can be produced using the RGB system.
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