A few notes about this function...
This function will only work on images where the palette is 256 colors or less. You also can not use imagetruecolortopalette() to reduce the palette on a true color PNG image that has greater than 256 colors in it's palette, then call this function. If you try to do this imagecolorexact() will report colors not being in the image when they are in the image!
1. works on png(s) 8bit/256 colors or less.
2. works on all gif(s)
3. does not work on any type of jpg/jpeg image.
imagecolorexact
(PHP 4, PHP 5, PHP 7, PHP 8)
imagecolorexact — Get the index of the specified color
Description
Returns the index of the specified color in the palette of the image.
If you created the image from a file, only colors used in the image are resolved. Colors present only in the palette are not resolved.
Parameters
-
image -
A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
-
red -
Value of red component.
-
green -
Value of green component.
-
blue -
Value of blue component.
Return Values
Returns the index of the specified color in the palette, or -1 if the color does not exist.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
image expects a GdImage
instance now; previously, a valid gd resource was expected.
|
Examples
Example #1 Get colors from the GD logo
<?php
// Setup an image
$im = imagecreatefrompng('./gdlogo.png');
$colors = Array();
$colors[] = imagecolorexact($im, 255, 0, 0);
$colors[] = imagecolorexact($im, 0, 0, 0);
$colors[] = imagecolorexact($im, 255, 255, 255);
$colors[] = imagecolorexact($im, 100, 255, 52);
print_r($colors);
// Free from memory
imagedestroy($im);
?>The above example will output something similar to:
Array
(
[0] => 16711680
[1] => 0
[2] => 16777215
[3] => 6618932
)
See Also
- imagecolorclosest() - Get the index of the closest color to the specified color
add a note
User Contributed Notes 3 notes
jbr at ya-right dot com ¶
18 years ago
samtobia at geemail dot com ¶
13 years ago
A script that changes colors depending on get variable
important to note: I had little success with pngs and getting true red
gifs work much better
<?php
//0 is yellow, 1 is red, 2 is blue
$y = 1 - ceil($_GET["c"]/2);
$r = 1 - floor($_GET["c"]/2);
$b = floor($_GET["c"]/2);
$gd = imagecreatefromgif("example.gif");
imagecolorset($gd, imagecolorexact($gd, 255, 0, 0), $r*255, $y*255, $b*255);
imagecolorset($gd, imagecolorexact($gd, 191, 0, 0), $r*191, $y*191, $b*191);
imagecolorset($gd, imagecolorexact($gd, 128, 0, 0), $r*128, $y*128, $b*128);
imagecolorset($gd, imagecolorexact($gd, 255, 0, 0), $r*64, $y*64, $b*64);
header('Content-Type: image/gif');
imagegif($gd);
?>
info at educar dot pro dot br ¶
19 years ago
<?php
$src = "../images/pic.gif";
$red = 9;
$green = 9;
$blue = 4;
$pic0026 = imagecreatefromgif ( $src );
$ind = imagecolorexact ( $pic, $red, $green, $blue );
echo '<img src="../images/pic.gif" border="0" alt="pic" title="View pic" /><br /><br />';
echo "RED ( " . $red . " ) GREEN ( " . $green . " ) BLUE ( " . $blue . " )<br />-> Palette Index = " . $ind;
if ( $ind != -1 )
{
echo "<br />[ The color exists! ]";
}
else
{
echo "<br />[ The color does not exist! ]";
}
imagedestroy ( $pic );
?>
