I'm trying to figure out a problem for a program I'm writing. I am calculating color values, and they get premultiplied by the alpha. I want to figure out what the alpha was before hand and divide the color by that.
I have the new premultiplied alpha (let's say alpha is $.25$ or $25\%$)
$\alpha = .25 * .25$;
$\alpha = .0625$
Given this information, I want to figure out $.25$ from $.0625$
$.0625 = x \times x$
My math is super bad/rusty. Any help would be great!