system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do different colors have a different shade of gray when saturation is removed?

Like when I'm in photoshop and turn the picture to grayscale or remove the saturation.  


Red shades will always be darker than yellow ones for example.  


Why is that?
gpt
On the surface it seems like all three colors(red, green, and blue) should be weighted equally because that's what the pixel is made of; but it turns out that gives you a really crappy looking grayscale image.

Your eye is far more sensitive to green light than red or blue, and still more senstive to red than blue.  When the computer converts from RGB to grayscale it will give far more weight to the green value than the red which means 0,255,0(green) will end up being far brighter than 255,0,0(red) or 0,0,255(blue).  Since yellow has a green component it will end up being fairly bright.