Selection Coloring Algorithm

Question

I'm trying to generate a color that could highlight an item as "selected" based on the color of the current object. I've tried increasing some of the HSB values, but I can't come up with a generalized formula. Particularly, I have problems when working with white (a brighter white doesn't look much different than a regular white). There's no requirement that says I need to make it brighter, so some sort of "inverse" color would work well too. Are there any standard algorithms or techniques for doing something like this (I'm guessing yes, but I couldn't find any -- I'm not sure if there's a name for this)?

thanks,

Jeff

Answer 1

Maybe the negatif effect:

pseudo:

int red = originalColor.red
int green = originalColor.green
int blue = originalColor.blue

int newRed = 255 - red
int newGreen = 255 - green
int newBlue = 255 - blue

Color negativeColor = new Color(newRed, newGreen, newBlue)

Or adding a blue color-effect:

int red = originalColor.red
int green = originalColor.green
int blue = originalColor.blue

int newRed = 255 - red
int newGreen = 255 - green
int newBlue = 255 - blue + 100
if newBlue > 255 {
   newBlue = 255
   newRed = newRed - 50
   newGreen = newGreen - 50
   if newRed < 0 {newRed = 0}
   if newGreen < 0 {newGreen = 0}
}

Color negativeColor = new Color(newRed, newGreen, newBlue)

Answer 2

If you're using HSB, try shifting the hue by half the maximum value either up or down, that should give you the "opposite" color (also called the complementary color). However, this doesn't do you any good for the grey spectrum, which has no hue and will thus look identical.

If you do this with both hue and brightness, you will get a kind of "negative", which works in all cases. A true negative would have you "flip" the brightness value around the mid-point, but that doesn't work for medium-gray, which would still be medium-gray.

It not always possible to make a color brighter (what do you do with white?), so shifting both hue and brightness by half is the most reliable if you're looking for contrast.

Answer 3

You might find the tools at http://www.easyrgb.com/ give you some ideas.