Our sync will allow for product images to be in the following formats:
.jpg, .JPG, .JPEG
.gif (The site will convert it to a jpg once uploaded)
IMPORTANT NOTE: if you're still using one of our early first generation software connectors (eg. Webninja Ecommerce) we ONLY import .jpg images)
RECOMMENDATION: We generally recommend to simply stick with .jpg as these are the best compressed for Web use with the highest visible quality. It's also best that whichever image file type you use, that you keep it consistent across all your product images - eg. if you're going to use .gif - please be sure to use .gif for ALL your product images as otherwise there's the potential that you could have a mix-up later one with two images by the same name eg.
Your Windows system will allow both these files to exist in the same folder on your server, which will cause issues with the sync.
We don't allow images over 1MB and usually most JPG images should easily be compressed to as low as 250 - 500KB (this can easily be done within Photoshop - but there are other similar programs that can do this as well).
If the image is larger than 1MB - this can potentially cause issues with the sync as well as how the image displays online - so best practice is to keep it smaller.
WIDTH VS. HEIGHT
The image dimensions need to be no more than 1,000 x 1,000 pixels in height and width.
you can make them smaller than that, but there's really no reason for them to be any bigger than that due to how images are displayed within websites and web browsers - even modern 4k screens still wouldn't display it properly.
RECOMMENDATION: You can make your images rectangular if you want - however we usually recommend you make them square as this will keep it consistent across the board for all your products. If you have a real need to use rectangular images - then all your images will need to be the same ratio of height x width - otherwise your products will show-up either out of alignment on the product listings, or else some of your images may appear much smaller than others.
The key is consistency.
Let us know if this information has been helpful - we'd love to hear your feedback!