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2024-03-10
(PHP 5)
imagefilter — 对图像使用过滤器
说明
bool imagefilter ( resource$src_im
, int $filtertype
[, int $arg1
[, int $arg2
[, int $arg3
]]] )
imagefilter() 把过滤器
filtertype 应用到图像上，在需要时使用
arg1，arg2 和
arg3。
filtertype 可以是下列中的一个：
IMG_FILTER_NEGATE：将图像中所有颜色反转。
IMG_FILTER_GRAYSCALE：将图像转换为灰度的。
IMG_FILTER_BRIGHTNESS：改变图像的亮度。用
arg1 设定亮度级别。
IMG_FILTER_CONTRAST：改变图像的对比度。用
arg1 设定对比度级别。
IMG_FILTER_COLORIZE：与
IMG_FILTER_GRAYSCALE 类似，不过可以指定颜色。用
arg1，arg2 和
arg3 分别指定
red，blue 和
green。每种颜色范围是 0 到 255。
IMG_FILTER_EDGEDETECT：用边缘检测来突出图像的边缘。
IMG_FILTER_EMBOSS：使图像浮雕化。
IMG_FILTER_GAUSSIAN_BLUR：用高斯算法模糊图像。
IMG_FILTER_SELECTIVE_BLUR：模糊图像。
IMG_FILTER_MEAN_REMOVAL：用平均移除法来达到轮廓效果。
IMG_FILTER_SMOOTH：使图像更柔滑。用
arg1 设定柔滑级别。
Note: 此函数仅在与 GD 库捆绑编译的 PHP 版本中可用。
成功时返回 TRUE， 或者在失败时返回 FALSE。
Example #1 imagefilter() 灰度例子
<?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() 亮度例子
<?php
$im = imagecreatefrompng('sean.png');
if ($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20)) {
echo 'Image brightness changed.';
imagepng($im, 'sean.png');
} else {
echo 'Image brightness change failed.';
}
imagedestroy($im);
?>
Example #3 imagefilter() 上彩例子
<?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');
} else {
echo 'Green shading failed.';
}
imagedestroy($im);
?>
参数
image
由图象创建函数(例如imagecreatetruecolor())返回的图象资源。
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.
IMG_FILTER_PIXELATE: Applies pixelation effect
to the image, use arg1 to set the block size
and arg2 to set the pixelation effect mode.
arg1
IMG_FILTER_BRIGHTNESS: Brightness level.
IMG_FILTER_CONTRAST: Contrast level.
IMG_FILTER_COLORIZE: 红色成分的值。
IMG_FILTER_SMOOTH: Smoothness level.
IMG_FILTER_PIXELATE: Block size in pixels.
arg2
IMG_FILTER_COLORIZE: 绿色成分的值。
IMG_FILTER_PIXELATE: Whether to use advanced pixelation
effect or not (defaults to FALSE).
arg3
IMG_FILTER_COLORIZE: 蓝色成分的值。
arg4
IMG_FILTER_COLORIZE: Alpha channel, A value
between 0 and 127. 0 indicates completely opaque while 127 indicates
completely transparent.
返回值
成功时返回 TRUE， 或者在失败时返回 FALSE。
更新日志
版本
说明
5.3.0
Pixelation support (IMG_FILTER_PIXELATE) was added.
5.2.5
Alpha support for IMG_FILTER_COLORIZE was added.
范例
Example #4 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);
?>
Example #5 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.';
}
?>
Example #6 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($im);
}
else
{
echo 'Green shading failed.';
}
?>
Example #7 imagefilter() negate example
<?php
// Define our negate function so its portable for
// php versions without imagefilter()
function negate($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.';
}
?>
Example #8 imagefilter() 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);
?>
以上例程的输出类似于：
注释
Note: 此函数仅在与 GD 库捆绑编译的 PHP 版本中可用。
参见
imageconvolution() - 用系数 div 和 offset 申请一个 3x3 的卷积矩阵
