note 62395 added to function.imagefilter
| From: | santibari at fibertel dot com | Date: | Mon, 27 Feb 2006 19:37:34 +0000 |
| Subject: | note 62395 added to function.imagefilter | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-104505@lists.php.net to get a copy of this message | ||
A colorize algorithm wich preserves color luminosity (i.e black
will output black, and white will output white).
This works in PHP4 and is great for customizing interfaces
dinamically.
<?php
function colorize($img_src,$img_dest, $r, $g, $b)
{
if(!$im = imagecreatefromgif($img_src))
return "Could not use image $img_src";
//We will create a monochromatic palette based on
//the input color
//which will go from black to white
//Input color luminosity: this is equivalent to the
//position of the input color in the monochromatic
//palette
$lum_inp=round(255*($r+$g+$b)/765); //765=255*3
//We fill the palette entry with the input color at its
//corresponding position
$pal[$lum_inp]['r']=$r;
$pal[$lum_inp]['g']=$g;
$pal[$lum_inp]['b']=$b;
//Now we complete the palette, first we'll do it to
//the black,and then to the white.
//FROM input to black
//===================
//how many colors between black and input
$steps_to_black=$lum_inp;
//The step size for each component
if($steps_to_black)
{
$step_size_red=$r/$steps_to_black;
$step_size_green=$g/$steps_to_black;
$step_size_blue=$b/$steps_to_black;
}
for($i=$steps_to_black;$i>=0;$i--)
{
$pal[$steps_to_black-$i]['r']=$r-round($step_size_red*$i);
$pal[$steps_to_black-$i]['g']=$g-round($step_size_green*$i);
$pal[$steps_to_black-$i]['b']=$b-round($step_size_blue*$i);
}
//From input to white:
//===================
//how many colors between input and white
$steps_to_white=255-$lum_inp;
if($steps_to_white)
{
$step_size_red=(255-$r)/$steps_to_white;
$step_size_green=(255-$g)/$steps_to_white;
$step_size_blue=(255-$b)/$steps_to_white;
}
else
$step_size_red=$step_size_green=$step_size_blue=0;
//The step size for each component
for($i=($lum_inp+1);$i<=255;$i++)
{
$pal[$i]['r']=$r + round($step_size_red*($i-$lum_inp));
$pal[$i]['g']=$g + round($step_size_green*($i-$lum_inp));
$pal[$i]['b']=$b + round($step_size_blue*($i-$lum_inp));
}
//--- End of palette creation
//Now,let's change the original palette into the one we
//created
for($c = 0; $c < $palette_size; $c++)
{
$col = imagecolorsforindex($im, $c);
$lum_src=round(255*($col['red']+$col['green']
+$col['blue'])/765);
$col_out=$pal[$lum_src];
imagecolorset($im, $c, $col_out['r'],
$col_out['g'],
$col_out['b']);
}
//save the image file
imagepng($im,$img_dest);
imagedestroy($im);
}//end function colorize
?>
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Manual Page -- http://www.php.net/manual/en/function.imagefilter.php
Edit -- http://master.php.net/note/edit/62395
Del: integrated -- http://master.php.net/note/delete/62395/integrated
Del: useless -- http://master.php.net/note/delete/62395/useless
Del: bad code -- http://master.php.net/note/delete/62395/bad+code
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Del: non-english -- http://master.php.net/note/delete/62395/non-english
Del: in docs -- http://master.php.net/note/delete/62395/in+docs
Del: other reasons-- http://master.php.net/note/delete/62395
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