Description:
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When i change the quality parameter in the imagewebp function, the image returned is exactly the same. This parameter seems to have no effect on the conversion process. I've tested with jpeg and png images files. The file is well converted, but when i change the quality parameter to another value, nothing appear to change on image resulted.

Test script:
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$destination = '1.webp';
$origine = '1.png';
@$webp = imagewebp(imagecreatefrompng($origine), $destination);
$destination = '2.webp';
$origine = '2.jpg';
@$webp = imagewebp(imagecreatefromjpeg($origine), $destination);
$destination = '3.webp';
$origine = '1.png';
@$webp = imagewebp(imagecreatefrompng($origine), $destination,50);
$destination = '4.webp';
$origine = '2.jpg';
@$webp = imagewebp(imagecreatefromjpeg($origine), $destination, 50);
//Ok after that i open results in photoshop for a deeper analyse on change....but nothing appear to have changed !!!