About image sizes
Firefly automatically resizes all images so that you don’t need to worry about editing or resizing images before you use them.
Even if you upload a high resolution image, Firefly will make sure that when someone wants to view it on a page, the image will be a suitable size for the viewer’s device (and data plan!)
Firefly has no built-in upload size limits and offers generous timeout limits so that you can upload your images with confidence. The only thing to be aware of is that the better your own connection to the internet, the faster you will be able to upload. If you try to upload a lot of images on a poor connection, it may take a long time. If it is too slow or you have problems, it may work better if you try later or using a different connection.
When preparing images to create navigation, Firefly will automatically resize and crop these to fit correctly. If it’s important that the focus of the image remains in the centre, then you will need to edit your image so that it has roughly the same aspect ratio as Firefly uses (3:2).