Imagick::setImageCompressionQuality

(PECL imagick 2, PECL imagick 3)

Imagick::setImageCompressionQuality — 设置图片压缩的质量

说明

Imagick::setImageCompressionQuality ( int $quality ) : bool

设置图片压缩的质量

参数

quality: 配置压缩质量的整数

返回值

成功时返回 true。

错误／异常

错误时抛出 ImagickException。

User Contributed Notes

vhpvhp at msn dot com 08-Nov-2018 09:30


For a PNG image, `setImageCompressionQuality()` is not work at all, length of the generated files are totally same.



But I found an effective way, that is use `setOption('png:compression-level', 9)`, the value range is 0-9.

dylan dot arnold at gmail dot com 23-Aug-2012 03:23


I had strange results when trying to get good png compression.



I used Imagick::COMPRESSION_ZIP



Here are a few file sizes for a few compression levels.



0: 236,100

1: 274,035

9: 258,379

50: 241,282

100: 240,156



Note the best result at 0. Also I got thrown off for a long time trying to get similar results to gimp. Make sure your image depth is set to 8, it appears to be 16 bits per channel, at least for me.



You can check with identify -verbose filename.png



You can also strip a bit more file size with $image->stripImage();

Anonymous 20-Jun-2012 02:56


The default value fot the JPEG compression quality appears to be 86.

snipes2083 [at] yahoo com 28-Mar-2010 11:35


This example shows how to set the compression type, set the compression quality, create a thumbnail and remove unnecessary data in order to reduce file size.





This will use the following functions in reference:


Imagick::setImageCompression


Imagick::setImageCompressionQuality


Imagick::stripImage


Imagick::thumbnailImage


Imagick::writeImage





<?php


    $image = 'image.jpg';


    $directory = '/path/to/image';


    $image_location = $directory . "/" . $image;


    $thumb_destination = $directory . "/t" . $image;


    $compression_type = Imagick::COMPRESSION_JPEG;


   


    $im = new Imagick($image_location);


    $thumbnail = $im->clone;





    $thumbnail->setImageCompression($compression_type);


    $thumbnail->setImageCompressionQuality(40);


    $thumbnail->stripImage();


    $thumbnail->thumbnailImage(100,null);


    $thumbnail->writeImage($thumb_destination);


?>





Now, obviously you don't have to do so much with the variables and the file location.  I only used so many to demonstrate where the images are coming from and where they are going.





NOTE:  The $thumbnail->thumbnailImage(100,null); keeps the aspect ration by setting the second parameter to null.  Read about this at Imagick::thumbnailImage





There is another way to create thumbnails that works quite well if you want to crop the image rather than using the entire image.  Check out Imagick::cropThumbnailImage