Unfortunately, no. The roImageCanvas will not scale automatically. You'll need to adjust your layers according to the screen resolution.
Here's a previous discussion about this in which I provided some code that I use to accomplish this without too much headache:
https://forums.roku.com/viewtopic.php?f=34&t=47220&p=321624#p321271
My Channels: http://roku.permanence.com - Twitter: @TheEndlessDev
Instant Watch Browser (NetflixIWB), Aquarium Screensaver (AQUARIUM), Clever Clocks Screensaver (CLEVERCLOCKS), iTunes Podcasts (ITPC), My Channels (MYCHANNELS)