Rainbow gradient
Author
How would you create a rainbow gradient, like in Photoshop, that goes from red to blue?
I will refer you to this thread, which has some great techniques presented. Of course you will need to mmodify it to whatever language you are using, but the ideas are the same.
Author
Actually, I found something even better, with source code:
http://www.codeproject.com/miscctrl/gradient.asp
I can use the color wheel to get a rainbow effect I suppose.
A straight line in 3D color space from red to blue is not very colorful. :(
http://www.codeproject.com/miscctrl/gradient.asp
I can use the color wheel to get a rainbow effect I suppose.
A straight line in 3D color space from red to blue is not very colorful. :(
Here is some code that will find the hue on a color wheel. Values are in degrees. The language is Python but it should be easy to rewrite it in a different language.
To get the colors for a rainbow loop through the hues.
def getHue(self,hue): h = hue/60.0 i = int(math.floor(h)) f = (h-i)*255 q = 255-f if i is 0: r=255;g=f;b=0 elif i is 1: r=q;g=255;b=0 elif i is 2: r=0;g=255;b=f elif i is 3: r=0;g=q;b=255 elif i is 4: r=f;g=0;b=255 elif i is 5: r=255;g=0;b=q return [r,g,b]To get the colors for a rainbow loop through the hues.
you wanna make sure it starts and ends at the right color. real rainbows always start and end at the same colors, I just can't remember which ones.
real rainbows cycle colors this way :
ultraviolet (not visible), blue, indigo, purple, green, yellow, orange, red, infrared (not visible)
it really doesn't cycle like the hue wheel.
Phil.
ultraviolet (not visible), blue, indigo, purple, green, yellow, orange, red, infrared (not visible)
it really doesn't cycle like the hue wheel.
Phil.
An easy (and accurate) way to do a rainbow would be to do a walk across the visible light spectrum, i.e. just step a variable from 700 to 400 and then map that number into RGB values using standard cone response curves.
Quote:Original post by PixelPhil
real rainbows cycle colors this way :
ultraviolet (not visible), blue, indigo, purple, green, yellow, orange, red, infrared (not visible)
it really doesn't cycle like the hue wheel.
Phil.
purple between indigo and green? not with my eyes, but your mileage may vary.
Quote:Original post by EelcoYeah, purple (violet) and blue should be switched. Roy G. Biv to the rescue! [grin]Quote:Original post by PixelPhilpurple between indigo and green? not with my eyes, but your mileage may vary.
ultraviolet (not visible), blue, indigo, purple, green, yellow, orange, red, infrared (not visible)
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