Evaluating RGB?

[teacherguy]

I would like to change the drop shadow behind text from black to white depending on the textcolor that the user selects. Does anyone have a way of evaluating the RGB in order to determine a darker color (say blue) from a lighter one (say yellow)?

[dunbarx]

Hi.

Well, "0,0,0" is pretty light, and if you start increasing the values of any of the three RGB values, the color will get "darker".

But is full yellow darker than full red? No, I guess. I think it better if you limit the color options to a fixed set, and create a look-up table so that you can map one to the other as you desire.

Craig Newman

[jacque]

I think you're looking for luminance values:

http://runtime-revolution.278305.n4.nab ... l#a4709206

[teacherguy]

Superb, thanks Jacque