What's the best way to darken a color until it is readable?

I have a series of titles are have an associated color, but some of these colors are very light and any text drawn in them is unreadable. I've been messing around with HSB and I can't seem to get an algorithm down that darkens the color without making it look silverish.

I think I want to alter the saturation too. Is there a standard way of doing this?

What's the best way to darken a color until it is readable?

I have a series of titles which have an associated color, but some of these colors are very light and any text drawn in them is unreadable. I've been messing around with HSB and I can't seem to get an algorithm down that darkens the color without making it look silverish.

I think I want to alter the saturation too. Is there a standard way of doing this?