imagecolorexact

(PHP 4, PHP 5, PHP 7)

imagecolorexact — Get the index of the specified color

Descrierea

imagecolorexact ( resource $image , int $red , int $green , int $blue ) : int

Returns the index of the specified color in the palette of the image.

Dacă ați creat imaginea din fișier atunci sunt determinate doar culorile utilizate în imagine. Culorile prezente doar în paletă nu sunt determinate.

Parametri

image: O resursă - imagine, întoarsă de una din funcțiile de creare a imaginilor, cum ar fi imagecreatetruecolor().
red: Valoarea componentei roșii.
green: Valoarea componentei verzi.
blue: Valoarea componentei albastre.

Valorile întoarse

Returns the index of the specified color in the palette, or -1 if the color does not exist.

Exemple

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);
?>

Exemplul de mai sus va afișa ceva similar cu:

Array
(
    [0] => 16711680
    [1] => 0
    [2] => 16777215
    [3] => 6618932
)

A se vedea și

imagecolorclosest() - Get the index of the closest color to the specified color

add a note

User Contributed Notes 3 notes

down

jbr at ya-right dot com ¶

18 years ago


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.

down

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);

?>

down

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 );

?>

add a note