In which resolution should I upload my images to Assembler?

When uploading images from your desktop to Assembler you must upload:

Sizes of the images

HI and LO renditions size

The recommended size for the full screen pictures for iPad is:

The recommended size for the full screen pictures for Email are:

In this case the images could be smaller depends on the use (e.g. a logo could be 400 pixel width if that is the biggest size it will be used on the emails)