php教程

Imagick::setImageCompressionQuality

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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

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