php man page for imagecolorat

IMAGECOLORAT(3) 							 1							   IMAGECOLORAT(3)

imagecolorat - Get the index of the color of a pixel

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

DESCRIPTION
	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:

PARAMETERS
	      o $
		image -An image resource, returned by one of the image creation functions, such as imagecreatetruecolor(3).

	      o $x
		- x-coordinate of the point.

	      o $y
		- y-coordinate of the point.

RETURN VALUES
	Returns the index of the color.

EXAMPLES
       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);
	      ?>

	      The above example will output something similar to:

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

       Example #2

	      Human-readable RGB values using imagecolorsforindex(3)

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

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

	      var_dump($colors);
	      ?>

	      The above example will output something similar to:

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

SEE ALSO
       imagecolorset(3), imagecolorsforindex(3), imagesetpixel(3).

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