使用IMagick / ImageMagick使图像的一部分透明 [英] Make part of an image transparent with IMagick/ImageMagick

问题描述

我希望使用IMagick使图像的一部分（或实际上是几个部分）透明，这样我就可以将它用作不同图像上的遮罩。我无法用简单的方式想出任何方式。

I wish to make part (or in fact, several parts) of an image transparent using IMagick, such that I can use it as a mask over a different image. I can't figure out any way of doing this in an simple fashion.

所以说我的起始图像如下所示，其中X是任何颜色：

So say my starting image is represented as below, where X is any color:

XXXXXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXXXXX

然后我希望能够使某些矩形区域透明（所以它最终有点像打卡）：

Then I want to be able to make certain rectangular regions transparent (so it ends up a bit like a punch-card):

XXXXXXXXXXXXX
X  XXXXXXXXXX
X  XXXX  XXXX
XXXXXXX  XXXX
XXXXXXXXXXXXX

有谁知道这样做的好方法？谢谢。

Does anyone know of a good way of doing this? Thanks.

推荐答案

想出来。

//Open your image and get its dimensions
$image = new Imagick('image.png');
$height = $image->getImageHeight();
$width = $image->getImageWidth();

//Create a new transparent image of the same size
$mask = new Imagick();
$mask->newImage($width, $height, new ImagickPixel('none'));
$mask->setImageFormat('png');

//Draw onto the new image the areas you want to be transparent in the original
$draw = new ImagickDraw();
$draw->setFillColor('black'); 
$draw->rectangle( 10,10,100,100 );
$mask->drawImage( $draw );

//Composite the images using Imagick::COMPOSITE_DSTOUT
$image->compositeImage($mask, Imagick::COMPOSITE_DSTOUT, 0, 0, Imagick::CHANNEL_ALPHA); 

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