Finally I modified lib/Varien/Image/Adapter/Gd2.php
The jpeg images are generated using the php imagejpeg function using the default quality, which is 75% (= sometimes not enough to get a good quality).
So I hardcoded a quality that suits my needs, thus :
- I upload images in jpeg 100% in the product creation process
- they are processed by the system (resizing, watermark if any, ...)
- they are saved in the media / cache folders ... using imagejpeg with the new quality parameter
and I got nice pictures now !
Do do it right I should have had a “jpeg quality” parameter in the admin but I don’t have the time now ... I have a shop to open
Is it possible to disable this feature completely.
I prefer to compress my image on a image by image basis.
And another question, is there a easy way to switch to a different “viewer” for images. Something more like the slide-style viewer on The Climbing Shop.
I think is a very good idea for the next releases of Magento, we can disable easely the jpg compression, because when i save the pictures with photoshop they are already optimized !
@FOOMAN: Excellent! This solved my problem with poor quality images in my store view.
The inbuilt compression worked well on bigger images, but I got problems on small images, especially that I had to resize before I uploaded.
After this fix, I can have Photoshop take care of the image optimizing.