imagefilter — 对图像使用过滤器

2018-04-18 20:52:51
linefo
427
最后编辑:linefo 于 2018-04-18 21:00:32

imagefilter

(PHP 5, PHP 7)

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 arg1arg2arg3

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 arg1arg2arg3 分别指定 redbluegreen。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 (
$im && imagefilter($imIMG_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 (
$im && imagefilter($imIMG_FILTER_BRIGHTNESS20)) {
    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 ($im && imagefilter($imIMG_FILTER_COLORIZE02550)) {
    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(
$im && imagefilter($imIMG_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(
$im && imagefilter($imIMG_FILTER_BRIGHTNESS20))
{
    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($im && imagefilter($imIMG_FILTER_COLORIZE02550))
{
    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($im)
{
    if(
function_exists('imagefilter'))
    {
        return 
imagefilter($imIMG_FILTER_NEGATE);
    }

    for(
$x 0$x imagesx($im); ++$x)
    {
        for(
$y 0$y imagesy($im); ++$y)
        {
            
$index imagecolorat($im$x$y);
            
$rgb imagecolorsforindex($index);
            
$color imagecolorallocate($im255 $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) * 2imagesy($logo1));

// Apply pixelation to each instance, with a block 
// size of 3
imagefilter($logo1IMG_FILTER_PIXELATE3);
imagefilter($logo2IMG_FILTER_PIXELATE3true);

// Merge the differences onto the output image
imagecopy($output$logo10000imagesx($logo1) - 1imagesy($logo1) - 1);
imagecopy($output$logo2imagesx($logo2), 000imagesx($logo2) - 1imagesy($logo2) - 1);
imagedestroy($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:

Output of example : imagefilter() pixelate

注释

Note: 此函数仅在与 GD 库捆绑编译的 PHP 版本中可用。

参见