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.
(PECL imagick 2, PECL imagick 3)
Imagick::setImageCompressionQuality — 设置图片压缩的质量
$quality): bool设置图片压缩的质量
quality配置压缩质量的整数
成功时返回 true。
错误时抛出 ImagickException。
示例 #1 Imagick::setImageCompressionQuality()
<?php
function setImageCompressionQuality($imagePath, $quality) {
$imagick = new \Imagick(realpath($imagePath));
$imagick->setImageCompressionQuality($quality);
header("Content-Type: image/jpg");
echo $imagick->getImageBlob();
}
?>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.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();The setImageCompressionQuality method accepts an integer value as its argument, representing the desired compression quality for the image, from 0 to 100, where 0 represents the lowest quality (highest compression, most lossy), and 100 represents the highest quality (lowest compression, lossless).
* Quality 0: Lowest quality, highest compression, most lossy. This will result in a very small file size, but the image will likely have noticeable artifacts and reduced clarity.
* Quality 100: Highest quality, lowest compression, lossless. The image will retain all its original details, but the file size will be larger.
In most cases, a quality value between 70 and 90 provides a good balance between file size and image quality. However, the optimal value depends on your specific use case and the level of compression you can tolerate while maintaining acceptable image clarity. It's best to experiment with different quality values to find the one that best suits youThis 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