Watermark !!

-- HikaShop version -- : 3.0.1
-- Joomla version -- : 3.7
-- PHP version -- : 5.6

hello,
I have a multi-vendor shop and for products, we have many pictures that vendors upload them, and we need to use watermark But watermark has some problems

1-it does not support JPG format for Opacity option (when I use jpg format, opacity does not work)
2-we don't have the option to repeat watermark in the picture! it causes problem with pictures in different resolution, if we use big picture watermark come in one corner only! for solving this problem I need to use PNG picture with high resolution with repeated watermark but it increase my pictures size
3-some time it increase image size unexpectedly like this: file, 90kb