Hi,
Thanks for using our templates

There are several things that can cause lines to appear between the images:
1) if one of the images has larger height or width
2) if the text in the cell is too large (large font size or a lot of text)
3) if you don't specify explicitly the cell padding and spacing of the table to be 0
4) sometimes a missing 'valign' and 'align' attributes can cause it
If you can tell us which template did you use or better give us a URL where you have the customized template I will take a look and I will give you some more info
Best wishes,
Yuri