PIxel -- GreyScale or RGB If RGB, it has three channels/values for red, blue, and green. Why use green and not yellow? --> Apparantly RYB being the primary colors is lie.. There are two different types of color mixing, additive and subtractive. RGB is addative, meaning, if you mix them all in equal parts you will get white. Adding them produces light, which is useful for screens. Source0.
In GrayScale, the RGB channels are exactly the same (why? -- my previous question answered this!). GreyScale requires 3 times less space.
Two groups -- faces and not faces.
Features are kernels?
Go thru image in cascading process