Open andrews05 opened 8 years ago
I can confirm the problem with this code (with PHP7, Imagick 3.4.3RC1, ImageMagick 7.0.2):
$i = new Imagick('lenna.png');
$i->setImageFormat("png");
$i->setImageCompressionQuality(5);
$i->writeImage("out05.png");
All quality values (0-99) produce a 474630 byte file. PNG q=5 should skip the zlib compression step, which should produce a much larger file.
Using convert
results in different output sizes:
$ convert lenna.png -quality 5 out05c.png
$ ls -l out05c.png
.. 754255 bytes ..
However, using the other quality setter method works for me:
$i = new Imagick('lenna.png');
$i->setImageFormat("png");
$i->setCompressionQuality(5);
$i->writeImage("out05.png");
Now, the q5 png is 754255 bytes. As the q default (in ImageMagick) is 75, q=75 results in the already seen 474630 bytes file.
The ImageMagick png coder reads the quality from the image_info
struct, which can be altered with MagickSetCompressionQuality()
(from Imagick::setCompressionQuality()
).
Interestingly, this method is not able to set the quality for other image (output) formats such as JPG. Here, q=5 should produce a small file, but it doesn't:
::setCompressionQuality(5) -> 110746 bytes
::setImageCompressionQuality(5) -> 3229 bytes
The ImageMagick JPG coder reads the quality directly from the Image
struct (although the image_info
is also present). convert
works as aspected with jpg output, too. Somehow, convert
manages to set the quality in both places.
Thanks for investigating this, and thanks for pointing out the alternative! Happy to use that instead.
setImageCompressionQuality()
is not work at all, length of the generated files are totally same, only a few bytes are different.
But I found an effective way, that is use setOption('png:compression-level', 9)
, the value range is 0-9
.
Hi @LIXiangChen ,
I made some test with image compression in a previous thread here:
https://github.com/ImageMagick/ImageMagick/issues/29#issuecomment-143263506
Apparently it is $image->setCompressionQuality() that should be used for png images.
Hi @Danack ,
Yes, I saw that post. Even though setCompressionQuality() is available, the unavailability of setImageCompressionQuality() is still doesn't make sense. I tend to think that this is a bug. Use setOption() is also good, at least it command is very clear.
Did you try something like:
$image->setImageCompression(Imagick::COMPRESSION_ZIP);
$image->setImageCompressionQuality(5);
(basically taken from user comments on http://php.net/manual/en/imagick.setimagecompressionquality.php)
FTR, this issue had also reported as https://bugs.php.net/77127 which I've now closed as duplicate.
Regarding the issue at hand: Imagick::setImageCompressionQuality() is a thin wrapper over MagickSetImageCompressionQuality(), and the quality parameter is clearly documented as
the image compression tlityype.
That says it all. ;)
I'm using Imagick 3.4.1 with ImageMagick 6.9.5-3 (built with mozjpeg). I load a png image in Imagick, fiddle with setImageCompressionQuality and then write it out again but no matter what I set the quality to, the filesize doesn't change. If I run ImageMagick
convert
on the same file, the quality setting works fine. Any idea why this would be? Are there some other options I need to set?