PHP: imagecolorstotal

User Contributed Notes
imagecolorstotal

Felix Rusu <webmaster at betania dot ro>
10-Apr-2004 04:19


Actually that is not true.

When you use for example imagecreatefromjpeg() you create a truecolor image resource (as with the other truecolor image types). If you try to get the number of colors using imagecolorstotal() you get 0 (thats what happened to me at least). Instead you must convert the trucolor resource to pallete resource. You have to do that like this:



<?

$simg=createfromjpeg("somejpeg.jpg");

imagetruecolortopalette($simg, false, 256);

$colors=imagecolorstotal($simg);

?>



Check the manual for the function signature.



Cheers.

love at tobe dot spamed
26-Jan-2004 03:33


to mgi : imagecolorstotal() function use a resource image. So doesn't take care about the image file format used. Even if you use a non-palette file format such as jpeg, it should work because it uses the palette built in the resource image... I'm wondering if I'm true.

black-eye at web dot de
01-Nov-2003 09:34


I created a function to count the colors in a .gif file automatically. Works perfect on Win2k Servers



<?PHP

function bildinfo($bild)

{

/*

******* FUNCTION BILDINFO() ******* ******* ******* *******

******* ******* ******* ******* ******* ******* ******* *******

******* Copyright 2003 by www.BLACKEYE.org ******* *******

******* ******* ******* ******* ******* ******* ******* *******

Please don't change the copyright in this file. You can modify

this file, but NEVER remove the copyright !

If YOU were the creator of this function, you would say the

same, eh ? :)



For more informations / How to use:

HOMEPAGE: www.blackeye.org

******* ******* ******* ******* ******* ******* ******* *******

*/

$fp = fopen($bild, "rb"); // Open image in binary mode (for windows)

$f = fread($fp, filesize($bild));

$c = bin2hex($f); // Binary file -> Hex

$c = ereg_replace("5c30", "0000", $c); // In gif-files "5c30" stands for real "00" values. why ? i dont know

$b = $c;



$pos = strpos($c, "fe0102"); // 6 Byte termination for the color table

if ($pos > 0)

{

$c = substr($c, 26);

$c = substr($c, 0, strpos($c, "fe0102")); // Termination for the color table of non-transparent images

}

else

{

$c = substr($c, 26);

$c = substr($c, 0, strpos($c, "21f904")); // Termination for the color table

}



echo "<table border='0'>";



$i = 0;

$y = 0;

$str = "";

$pix = chunk_split($c, 6, ";"); // 6 Char long block (color)

$pix = explode(";",$pix);

sort($pix);

foreach($pix as $col)

{

if ($col && !ereg($col.";", $str) && strlen($col) == 6) // So that no color is twice in the list

{

$str .= $col.";";

$i++; // F�r die Table anzeige

$y++; // Anzahl Farben

if ($i == 1) { echo ""; }

echo "<td width='6' height='8' bgcolor='#$col' style='border:1px solid #000000;font-size:1px;' title='�2003 by www.BLACKEYE.org'>";

echo " ";

echo "</td>";

if ($i == 10)

{

echo ""; $i = 0;

}

}

}



echo "</table>";

echo $y." visible colors";

}



$bild = ""; // Imagefile

bildinfo($bild);

?> 

Only copy & paste this text into your .php file, where you want to show the image.

mgi at humbug dot net
16-Jul-2003 12:54


I would assume that since it says "number of colors in an image's palette" that the behaviour is undefined for non-paletted image types (for example, JPEG). It would probably only make sense to use it for 256 (8-bit) indexed images.

imagecolorstotal

Description