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Lecture 19: Introduction to Color Science (11)

An interesting fact about color very useful in astronomy is that the color of a star tells you the temperature. A star can be modeled as a blackbody, or an opaque and non-reflective body. Wien's displacement law states that the black-body radiation curve peaks at a wavelength that is inversely proportional to the temperature of the object.


I also find it interesting to note that humans are able to perceive more shades of green than any other color, probably due to necessity of being able to differentiate between plants. Blue is also widely considered to be the most "pleasing" color, most likely because of the sky.


Why is it that printing uses CMYK and LCD screens use RGB? Could LCD screens be RYB having yellow replace green?


Printing uses CMYK since the ink is absorbing light. Red ink is red since it absorbs all other colors and only reflects the color red. Similarly, green ink is green because it absorbs everything else. Consequently, if we were to layer red and green in the printing process, we'd just get black, which is not that useful to us from a color mixing perspective. To address this issue, we use colors (CMYK) that instead each reflect a mix of RGB (e.g., Yellow only reflects Red and Green, Magenta only reflects Red and Blue--combining these will result the reflection of only Red). For more information, the fundamental idea behind CMYK is the subtractive color model. In contrast, LCD screens can use RGB because they emit light.


It has always blown my mind that our eyes can discern so many possible colors. For example if you go from a color space with thousands of colors to a color space with millions of colors, the difference is very obvious. I also wonder if there is a minimum threshold for color differences in the same way that there is a minimum spatial length or time (like planck).


In Photoshop, sometimes people prefer to switch Lab color space to adjust colors. I'm wondering why / how it is better than RGB.


LAB is a system that is more intuitive for people to understand than RGB, which is how computer displays represent colors. That's probably why it's used instead of the other systems.


One interesting one is that color affects our depth perception. We perceive warmer colors to be closer and cooler colors to be further away.


Red is the first color that can be perceived by a baby.


Speaking of depth perception, color is actually a big part of how we perceive distance in the real world. The amount of contrast and saturation of colors as well as the spectrum can hint at the distance of a scene/object. Here's a link I found regarding color in depth perception:


Speaking of animals seeing different amounts of color - apparently mosquitos search for their next (literal) bite through vision, and are more attracted to dark colors, especially blue. So dress with lighter colours everyone!

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