Funny, was just messing with this now. Here's a striped down version.
Find RGB first:
c = 0xc0ffee;
r = c >> 16 & 0xff;
g = c >> 8 & 0xff;
b = 0xff;
Brightness/Value according to HSV/HSB is simple:
l = Math.max(r, g, b); // 0 to 255
Lightness according to HSL is sort of simple too:
max = Math.max(r, g, b);
min = Math.min(r, g, b);
l = (max+min) / 2; // 0 to 255
*Actual* light brightness is a bit different, and depends on color
profile (this is an approximation):
lr = 0.212671;
lg = 0.715160;
lb = 0.072169;
l = (lr * r) + (lg * g) + (lb * b); // 0 to 255
The latter one is the 'right' way to measure the brightness of a color
(ie, 0x00ff00 is actually much brighter than 0x0000ff). The others are
mathematical representation models and doesn't reflect our perception of
brightness. Choosing the correct one will depend on what you're trying
to do.
References:
http://en.wikipedia.org/wiki/HSL_color_space
http://www.faqs.org/faqs/graphics/colorspace-faq
Zeh
Hans Wichman wrote:
Hi,
just guessing here, but i think converting them to HSB first might work.
Then you only need the B value.
hth
JC
On Thu, Jul 24, 2008 at 8:55 PM, Jim McIntyre <[EMAIL PROTECTED]> wrote:
Does anyone know a good formula for comparing brightness of RGB color
values?
Obviously, 0xCCCCCC is brighter than 0x333333. But one can't always infer
that a larger number is brighter than a smaller: 0x330000 is a larger
number, but much darker than, 0x00FFFF.
Would averaging (or simply adding) the three color components work, or is
it more nuanced than that?
Thanks,
Jim
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