I've searched the forum, and the topic has been treated dozens of times.
It seems that the algorithm used to generate the thumbnails from the images is uncapable of creating clean, sharp images. Probably it wasn't a very big issue some years ago, but now it's very noticeable considering nowadays mobile phone and computer screen standards (ultra high resolutions don't mix up well with JPEG artifacts!).
I've tried modifying the quality settings as stated in previous posts (in administrator/components/com_virtuemart/helpers/img2thumb.php --- return imagejpeg($new_img, $fileout, 100); ), but the difference was not noticeable at all, but the file size was nonetheless increased.
In those treads, it is proposed batch generation using Irfanview and other image editors but let's face it: it's rather unpractical! VM should provide a comprehensive all-in-one solution.
What is more important than making our stores and products look right?
do you know of a commonly available image library other than php GD?
the only alt. I know is Imagick (seems to be considered better) but afaik it is not widely available on hosts
Any solution has to be available on all common hosts
Quote from: juanvilchez on December 28, 2017, 23:00:35 PM
VM should provide a comprehensive all-in-one solution.
VM is a community project so if you have a solution for your perceived issue which is suitable for use on all types of server platform then please feel free to submit it.
If you need high quality image, use PNG and not jpg, of course in this case your image are bigger but you get better image quality.
Note that i added a webp convert in Vm Be Pro (https://shop.st42.fr/en/products/vm-be-pro-batch-product-edit.htm) and a punyPng button to get best PNG compression.
You can check here about webp : https://www.andrewmunsell.com/blog/png-vs-webp/
Note that my website image is not optimised for image quality, i prefer in my case faster render.
Here to compare sizes :
child-pro-phone_600x600.png 157 659
child-pro-phone_600x600.webp 12 750
vmproducts_samples.jpg 260 228 (quality 70% i think)
vmproducts_samples.webp 214 590
To use webp, you can use a simple rule in the .htaccess
# use webp
RewriteCond %{HTTP_ACCEPT} image/webp
RewriteCond %{DOCUMENT_ROOT}/$1.webp -f
RewriteRule (.+)\.(jpe?g|png)$ $1.webp [T=image/webp,E=accept:1]
Webp is not supported by all browser, but with this rule, it autoswitch by browser