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).
PHP Documentation Group IMAGEFILTER(3)