Technical FAQ
PHP Manual
CSS2 Manual
HTML Manual
JS Guide
JS Reference
PhpDock Manual
Nu-Coder Manual
PhpExpress Manual
PHP Joomla
Learn PHP
Last updated: Tue, 19 Sep 2006


(PHP 5)

imagefilter --  Applies a filter to an image


bool imagefilter ( resource src_im, int filtertype [, int arg1 [, int arg2 [, int arg3]]] )

imagefilter() applies the filter filtertype to the image, using arg1, arg2 and arg3 where necessary.

filtertype can be one of the following:

  • IMG_FILTER_NEGATE: Reverses all colors of the image.

  • IMG_FILTER_GRAYSCALE: Converts the image into grayscale.

  • IMG_FILTER_BRIGHTNESS: Changes the brightness of the image. Use arg1 to set the level of brightness.

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

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

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

  • IMG_FILTER_EMBOSS: Embosses the image.

  • IMG_FILTER_GAUSSIAN_BLUR: Blurs the image using the Gaussian method.

  • IMG_FILTER_SELECTIVE_BLUR: Blurs the image.

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

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

Note: This function is only available if PHP is compiled with the bundled version of the GD library.

Returns TRUE on success or FALSE on failure.

Example 1. imagefilter() grayscale example

$im = imagecreatefrompng('dave.png');
if ($im && imagefilter($im, IMG_FILTER_GRAYSCALE)) {
    echo 'Image converted to grayscale.';
    imagepng($im, 'dave.png');
} else {
    echo 'Conversion to grayscale failed.';


Example 2. imagefilter() brightness example

$im = imagecreatefrompng('sean.png');
if ($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20)) {
    echo 'Image brightness changed.';
    imagepng($im, 'sean.png');
} else {
    echo 'Image brightness change failed.';


Example 3. imagefilter() colorize example

$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');
} else {
    echo 'Green shading failed.';


Last updated: Tue, 19 Sep 2006