[edit] Last updated: Sat, 07 Jan 2012

imagecolorexact

(PHP 4, PHP 5)

imagecolorexact — Get the index of the specified color

설명

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

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.

인수

image: imagecreatetruecolor() 등의 이미지 생성 함수에서 반환한 이미지 자원.
red: Value of red component.
green: Value of green component.
blue: Value of blue component.

반환값

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

예제

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);
?>

위 예제의 출력 예시:

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

참고

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

imagecolorexactalpha

imagecolordeallocate

[edit] Last updated: Sat, 07 Jan 2012

add a note User Contributed Notes imagecolorexact

samtobia at geemail dot com 24-Mar-2011 04:11


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);



?>

jbr at ya-right dot com 18-Feb-2006 05:38


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.

info at educar dot pro dot br 16-Nov-2005 04:14


<?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