Hi,
The thumbnails you generate are 160x160 pixel size.
And you have activated the setting "force size" so the images must be "160x160" ; that's why you can have "borders" if the image is not a perfect square.
The image processing function will create transparent borders when using PNG but JPG does not handle the transparency, so the function will try to extract the background color which is in most case "white".
But it is possible to give in parameter of the function which will generate the thumbnail which background color will be used ; you can, if the paramter is not working properly, change it directly in the forum..
The different processes are explained in that thread :
www.hikashop.com/forum/product-category-...uct-image-thumb.html
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.