I just came across with this very strange problem.
The case: I have these 2 images:
The images are identical. The only difference is that the 2nd image has a white background.
But when you visit the product's page you can see that the 1st image's colors are blurry while the colors of the 2nd image are correct. (see the Green color)
I did the test with a fresh installation of Magento 1.9.3.1 without any extensions installed. The PHP version is 5.5.9-1ubuntu4.21
I also did the test with an online Magento demo. The results are the same. The green color is blurry.
It has nothing to with the ->setQuality()
option.
I did a test with $this->helper('catalog/image')->setQuality(100)
and the final result is the same. The image that Magento produces has spoiled colors.
Is it a Magento bug, a Zend bug or a PHP bug?