Our knowledge base explains in detail how to work with images in genARate. There it is mentioned that upload file size is restricted to 5MB. Besides that, you should make sure that the resolution of the image is just as big as it is needed in the context of your WonderPage. You should work on this in an external image editor and save the image in the appropriate size/resolution.
The stage size in genARate is 1000×1000 pixels – which means it does not make sense to import an image with e.g. 2000 pixels in width and just resize it in the editor so that it fits the stage.
Note: Working with higher resolutions does not have a positive impact on display quality – it will just unnecessarily increase the download time.
As genARate supports 3 different file formats (jpg, png & gif) it might make sense to experiment a little bit with which format produces the best visual result with the lowest file size. This can differ depending on the nature of the image (how many big single-colored areas does the image have etc.)
Animated GIFs are very demanding in terms of consuming processing power on mobile devices – therefore the recommendation is to use APGN or MP4 Files instead.