Force Image Size makes Black Borders

-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.3.6

Hi I have a site which has lots of different image sizes for categories and products
I want to make them uniform using "force image size" however when i use this with "keep ratio" the thumbnails get a black border either on the top and bottom or on the sides in the case of portrait shaped images - is it possible to change this border to white instead? where is the code to do this?
Thanks

Hi,

In the HikaShop Imager Helper, for the thumbnail generation ; by default the border should be white ; but I think that if you use a PNG (or GIF) image with transparency, it might be possible that the background color won't be loaded correctly.

Regards,