Background: I wanted a way of displaying some html with different shading depending on a given criterion. I didn't want completely different colors - 1 color with different levels of brightness.

This snippet will convert a hex color to RGB, shift the levels up and down by a given value, then convert back to HTML valid HEX (not necessarily web-safe). It returns:
1. lighter color than orig. 2. darker color than orig.

Potential Uses: Well, I am using this for a diary system, the cells in the month-view-calendar will be shaded diferently depending on how many meetings\reminders I have on that day. But I am sure you can thing of other reasons to do it.

Notes: It might not work so well when any of the RGB values are close to 0 or 255. There may also be a neater way of doing it.... Comments welcome...

my $silver = "c0c0c0";
my ($light_silver, $dark_silver) = color_munge(25,$silver);


sub color_munge {
    my @limits = (0, 255);
    my $off_set = shift;
    my $html_colour = shift;

    my @old = map hex, ($html_colour =~ /(..)(..)(..)/);
    
    my $brighter = join ('', map {$_ += $off_set; $_ = $limits[1] if $
+_ > $limits[1]; sprintf("%02X", $_); } @old);

    my $darker = join('', map {$_ -= 2 * $off_set; $_ = $limits[0] if 
+$_ < $limits[0]; sprintf("%02X", $_); } @old);
    
    return ($brighter,$darker);
}
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