How to extract RGB arguments as a list

Question

Although the following lines of code work fine they are very awkward.

My questions are below

a = RGBColor[1, 0, 0]
b = RGBColor[0, 1, 0]

Is there a more compact way to construct ab?

Can the three entries of RGBColor[u,v,w] be extracted as a list?

Can the RGBColor argument be entered as a list RGB[{list}]?

ab = RGBColor[a[[1]] + b[[1]], a[[2]] + b[[2]], a[[3]] + b[[3]]]
Graphics[{{a, Disk[{0, .5}, .5]}, {b, Disk[{.25, .5}, .5]}, {ab, 
   Disk[{.5, .5}, .5]}}]

Answer 1

Just use Apply (short form @@):

RGBColor @@ {1, 0, 0}

RGBColor[1, 0, 0]

List @@ RGBColor[1, 0, 0]

{1, 0, 0}

See: Applying Functions to Lists and Other Expressions

---

Okay, I actually missed the crux of your question because of the lack of formatting in the original.

You could get ab using Thread[a + b, RGBColor] -- see Thread.

Answer 2

To make all the assignments on one line:

colors = {{0, 0, 0}, {1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
{black, red, green, blue} = RGB @@@ colors

red => RGB[1, 0, 0]