There are a few types of image you will want to upload in BRM / RSM    

Inventory related

Category images - rectangular (Image should be 100x67px or 200x133px)

Product images  - rectangular (Image should be quite high resolution and rectangular, e.g. 

Extras images - square (image should be square and small  - e.g.100 x 100 )

Online booking

your store logo (for your emails) - normally square and quite small (e.g. 200 x 200 px) but can we pretty much whatever size you require, within reason!

your online booking banner (if you enable it) letterbox 1200 x 300 px


reservation type images rectangular 40 x 16 px (very small!)

Tours, Activities, Events etc

tour / activity image

today this is supplied externally.

See also

example images