"The maximum upload size is 2MB, also be aware that the image is going to be converted to greyscale and scaled down by the Target Manager. Take a look at the 'show features' view to see the results of this conversion. If you are working w/ high resolution images to develop a large scale target, my advice is to compose this target as a MultiTarget using multiple images."
Coudl you tell us what's the maximum size of a marker?
I can see that the downloaded marker bundles contain "marker preview images" (used in Unity Editor to display the marker). All preview image have maximum size 512. Is this the maximum for marker size?