Currently ArcGIS Online does not have the ability to zoom into a image services past the last generated tile. I am proposing that ESRI adds the ability to re-sample and stretch all image services, which would allow users to zoom closer into tiled images. Although the zoomed image would be blurry due to re-sampling it would help visualise high accuracy or high density data sets.
This functionality has been introduced to the ArcGIS collector app and I think AGOL maps would also benefit from the same functionality
