Function.imagefilter

Aus PHP-Wiki

imagefilter — Applies a filter to an image

Beschreibung

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

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

Parameter-Liste

image

• Eine von den verschiedenen Erzeugungsfunktionen wie imagecreatetruecolor() gelieferte Grafikresource.

filtertype

• 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 and arg4 for the alpha channel. 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.

arg1

• IMG_FILTER_BRIGHTNESS: Brightness level. IMG_FILTER_CONTRAST: Contrast level. IMG_FILTER_COLORIZE: Value of red component. IMG_FILTER_SMOOTH: Smoothness level.

arg2

• IMG_FILTER_COLORIZE: Value of green component.

arg3

• IMG_FILTER_COLORIZE: Value of blue component.

arg4

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

Rückgabewerte

Gibt bei Erfolg TRUE zurück, im Fehlerfall FALSE.

ChangeLog

Version Beschreibung 5.2.5 Alpha support for IMG_FILTER_COLORIZE was added.

Beispiele

Beispiel #1 imagefilter() 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);
?>

Beispiel #2 imagefilter() 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.';
}
?>

Beispiel #3 imagefilter() 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.';
}
?>

Beispiel #4 imagefilter() 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.';
}
?>

Anmerkungen

Hinweis: Diese Funktion steht nur zur Verfügung, wenn PHP mit der GD Bibliothek übersetzt wurde, die mit PHP zusammen erhältlich ist.

Siehe auch

• imageconvolution()