The size limits on images are in place so that members with slower connections don't have to wait forever for images to load and to minimize bandwidth used by TTB, not to mention storage space.
If you Google "photo resizer" you will find sites where you can resize your pictures online and download the resized pictured to your computer and also free software that you can download to your computer so that you can resize your pictures locally.
I played around with the first online result that I received, www.picresize.com
, and it seemed to be fairly straightforward and easy to use. If you look closely, in the bottom left corner is an option to do multiple pictures at once. There is a place to specify maximum size; our maximum size is 1500KB. This is just one of many sites that offer resizing for free that I happened to try.
You can also use download.cnet.com
to search for photo resizing software to download to your computer. There you can specify whether you are using a Mac or a PC and also select for only free results.
If you encounter problems with this process please let me know. I'm happy to help.