crazy hex color question

[frijole]

i would like to find a way to take 2 hexadecimal colors and multiply them together, or take the average and come out with an intermediate color. Sounds like a good test question. any ideas?

[btherl]

What would you be multiplying them together for?  I understand why you would want to take the average.

 

As for how to do it, base_convert() will convert a hex string into an integer, after which you can use normal maths on it.  Or are you looking for a method that will operate on actual hex strings themselves?

 

Edit: And for averaging the colours, you would need to split the colour into the red green and blue components before doing the maths (at least that makes it easier).

[Barand]

You could split them into their red, green and blue components and average those

 

<?php
$col_a = 0xFFFF00;
$col_b = 0xEB9642;

$a = sprintf('#%06X', $col_a);
$b = sprintf('#%06X', $col_b);
$c = sprintf('#%06X', avgColor ($col_a, $col_b));

echo "<span style='background-color: $a'>--$a--</span>";
echo "<span style='background-color: $c'>--average--</span>";
echo "<span style='background-color: $b'>--$b--</span>";

function colorSplit($c)
{
    $red = ($c >> 16) & 0xFF;
    $green = ($c >>  & 0xFF;
    $blue = $c  & 0xFF; 
    return array($red, $green, $blue);
}

function avgColor ($a, $b)
{
    $a = colorSplit($a);
    $b = colorSplit($b);
    
    $r = ($a[0] + $b[0]) / 2;
    $g = ($a[1] + $b[1]) / 2;
    $b = ($a[2] + $b[2]) / 2;
    
    return ($r << 16) + ($g <<  + $b;
}

?>

[dave420]

I'd suggest using one of the existing colour-distance functions, such as this one:

 

http://www.compuphase.com/cmetric.htm

 

If you want to find the intermediary, that page should send you in the right direction.

[cooldude832]

I believe hex codes are in the form

RRGGBB

 

so if u want to find a "intermediate"

take the avg of the RR avg of GG and avg BB and then use those (as integers not floats)

 

you will of course need to first split it into single digits, then convert from base16 to base 10 numbers (so A = 10 B = 11 C = 12) and then avg and convert back to 16 (14 = E 15 = F)  and then rebuild the new hex.  I don't know if it will be a quote "intermediate", but you can probably tweak it somehow to do what you want.

 

 

Alternatively you can use equations to go from the hex codes to RGB and then probably get a more refined "intermediate"