update : 2015.11.03
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Get the index of the color of a pixel
GD and Image 함수 목록
PHP Manual

imagecolorat

(PHP 4, PHP 5, PHP 7)

imagecolorat — Get the index of the color of a pixel

설명

int imagecolorat ( resource $image , int $x , int $y )

Returns the index of the color of the pixel at the specified location in the image specified by image.

If PHP is compiled against GD library 2.0 or higher and the image is a truecolor image, this function returns the RGB value of that pixel as integer. Use bitshifting and masking to access the distinct red, green and blue component values:

인수

image

imagecreatetruecolor() 등의 이미지 생성 함수에서 반환한 이미지 자원.

x

x-coordinate of the point.

y

y-coordinate of the point.

반환값

Returns the index of the color.

예제

Example #1 Access distinct RGB values

<?php
$im = imagecreatefrompng("php.png");
$rgb = imagecolorat($im, 10, 15);
$r = ($rgb >> 16) & 0xFF;
$g = ($rgb >> 8) & 0xFF;
$b = $rgb & 0xFF;

var_dump($r, $g, $b);
?>

위 예제의 출력 예시:

int(119)
int(123)
int(180)

Example #2 Human-readable RGB values using imagecolorsforindex()

<?php
$im = imagecreatefrompng("php.png");
$rgb = imagecolorat($im, 10, 15);

$colors = imagecolorsforindex($im, $rgb);

var_dump($colors);
?>

위 예제의 출력 예시:

array(4) {
  ["red"]=>
  int(119)
  ["green"]=>
  int(123)
  ["blue"]=>
  int(180)
  ["alpha"]=>
  int(127)
}

참고

GD and Image 함수 목록
PHP Manual