IMAGEFILTER(3)								 1							    IMAGEFILTER(3)

imagefilter - Applies a filter to an image

SYNOPSIS

       bool imagefilter (resource  $image, int	$filtertype, [int  $arg1], [int  $arg2], [int  $arg3], [int  $arg4])

DESCRIPTION

       imagefilter(3) applies the given filter $filtertype on the $image.

PARAMETERS

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

	      o $filtertype
		-$filtertype can be one of the following:

		     o IMG_FILTER_NEGATE: Reverses all colors of the image.

		     o IMG_FILTER_GRAYSCALE: Converts the image into grayscale.

		     o IMG_FILTER_BRIGHTNESS:  Changes	the  brightness  of the image. Use $arg1 to set the level of brightness. The range for the
		       brightness is -255 to 255.

		     o IMG_FILTER_CONTRAST: Changes the contrast of the image. Use $arg1 to set the level of contrast.

		     o IMG_FILTER_COLORIZE: Like IMG_FILTER_GRAYSCALE, except you can specify the color. Use $arg1, $arg2 and $arg3 in the form of
		       $red, $green, $blue and $arg4 for the $alpha channel. The range for each color is 0 to 255.

		     o IMG_FILTER_EDGEDETECT: Uses edge detection to highlight the edges in the image.

		     o IMG_FILTER_EMBOSS: Embosses the image.

		     o IMG_FILTER_GAUSSIAN_BLUR: Blurs the image using the Gaussian method.

		     o IMG_FILTER_SELECTIVE_BLUR: Blurs the image.

		     o IMG_FILTER_MEAN_REMOVAL: Uses mean removal to achieve a "sketchy" effect.

		     o IMG_FILTER_SMOOTH: Makes the image smoother. Use $arg1 to set the level of smoothness.

		     o IMG_FILTER_PIXELATE:  Applies  pixelation effect to the image, use $arg1 to set the block size and $arg2 to set the pixela-
		       tion effect mode.

	      o $arg1
		-

		     o IMG_FILTER_BRIGHTNESS: Brightness level.

		     o IMG_FILTER_CONTRAST: Contrast level.

		     o IMG_FILTER_COLORIZE: Value of red component.

		     o IMG_FILTER_SMOOTH: Smoothness level.

		     o IMG_FILTER_PIXELATE: Block size in pixels.

	      o $arg2
		-

		     o IMG_FILTER_COLORIZE: Value of green component.

		     o IMG_FILTER_PIXELATE: Whether to use advanced pixelation effect or not (defaults to FALSE).

	      o $arg3
		-

		     o IMG_FILTER_COLORIZE: Value of blue component.

	      o $arg4
		-

		     o IMG_FILTER_COLORIZE: Alpha channel, A value between 0 and 127. 0 indicates completely opaque while 127 indicates completely
		       transparent.

RETURN VALUES

	Returns TRUE on success or FALSE on failure.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.0	|						    |
       |	|						    |
       |	|  Pixelation  support	(  IMG_FILTER_PIXELATE) was |
       |	| added.					    |
       |	|						    |
       | 5.2.5	|						    |
       |	|						    |
       |	|  Alpha support for IMG_FILTER_COLORIZE was added. |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      imagefilter(3) grayscale example

	      <?php
	      $im = imagecreatefrompng('dave.png');

	      if($im && imagefilter($im, IMG_FILTER_GRAYSCALE))
	      {
		  echo 'Image converted to grayscale.';

		  imagepng($im, 'dave.png');
	      }
	      else
	      {
		  echo 'Conversion to grayscale failed.';
	      }

	      imagedestroy($im);
	      ?>

       Example #2

	      imagefilter(3) brightness example

	      <?php
	      $im = imagecreatefrompng('sean.png');

	      if($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20))
	      {
		  echo 'Image brightness changed.';

		  imagepng($im, 'sean.png');
		  imagedestroy($im);
	      }
	      else
	      {
		  echo 'Image brightness change failed.';
	      }
	      ?>

       Example #3

	      imagefilter(3) colorize example

	      <?php
	      $im = imagecreatefrompng('philip.png');

	      /* R, G, B, so 0, 255, 0 is green */
	      if($im && imagefilter($im, IMG_FILTER_COLORIZE, 0, 255, 0))
	      {
		  echo 'Image successfully shaded green.';

		  imagepng($im, 'philip.png');
		  imagedestroy($im);
	      }
	      else
	      {
		  echo 'Green shading failed.';
	      }
	      ?>

       Example #4

	      imagefilter(3) negate example

	      <?php
	      // Define our negate function so its portable for
	      // php versions without imagefilter()
	      function negate($im)
	      {
		  if(function_exists('imagefilter'))
		  {
		      return imagefilter($im, IMG_FILTER_NEGATE);
		  }

		  for($x = 0; $x < imagesx($im); ++$x)
		  {
		      for($y = 0; $y < imagesy($im); ++$y)
		      {
			  $index = imagecolorat($im, $x, $y);
			  $rgb = imagecolorsforindex($index);
			  $color = imagecolorallocate($im, 255 - $rgb['red'], 255 - $rgb['green'], 255 - $rgb['blue']);

			  imagesetpixel($im, $x, $y, $color);
		      }
		  }

		  return(true);
	      }

	      $im = imagecreatefromjpeg('kalle.jpg');

	      if($im && negate($im))
	      {
		  echo 'Image successfully converted to negative colors.';

		  imagejpeg($im, 'kalle.jpg', 100);
		  imagedestroy($im);
	      }
	      else
	      {
		  echo 'Converting to negative colors failed.';
	      }
	      ?>

       Example #5

	      imagefilter(3) pixelate example

	      <?php
	      // Load the PHP logo, we need to create two instances
	      // to show the differences
	      $logo1 = imagecreatefrompng('./php.png');
	      $logo2 = imagecreatefrompng('./php.png');

	      // Create the image instance we want to show the
	      // differences on
	      $output = imagecreatetruecolor(imagesx($logo1) * 2, imagesy($logo1));

	      // Apply pixelation to each instance, with a block
	      // size of 3
	      imagefilter($logo1, IMG_FILTER_PIXELATE, 3);
	      imagefilter($logo2, IMG_FILTER_PIXELATE, 3, true);

	      // Merge the differences onto the output image
	      imagecopy($output, $logo1, 0, 0, 0, 0, imagesx($logo1) - 1, imagesy($logo1) - 1);
	      imagecopy($output, $logo2, imagesx($logo2), 0, 0, 0, imagesx($logo2) - 1, imagesy($logo2) - 1);
	      imagedestroy($logo1);
	      imagedestroy($logo2);

	      // Output the differences
	      header('Content-Type: image/png');
	      imagepng($output);
	      imagedestroy($output);
	      ?>

	      The above example will output something similar to:[NOT DISPLAYABLE MEDIA]Output of example : imagefilter() pixelate

NOTES

SEE ALSO

       imageconvolution(3).

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