When I clear the image cache some of them are in good quality but some others are bad (when they ware good previoulsy).
I have tried GD 2.1 an ImageMagick 6.8 for same result.
What can I do to ionvestigate on that ?
Log in to Koken, go to Settings, then Image publishing and click Clear image cache. However, on a resource limited server clearing the entire image cache may fix one issue but introduce others. To fix an individual pixilated image, find the pixilated images(s) via the web browser. Then log into Koken and find the exact image(s) in the Library. Rotate the image and then rotate it back. This will force the server to re-render that specific image and the pixelation is gone. Also upgrade PHP to v7, it is significantly faster.