Way to test SD display

Probably an easy question… but how does one go about testing SD display type processes. If I have HD images and SD images, what can I set on my TV to test the older SD/480 format. I guess how do I make my 1080/HDTV TV appear to Roku as a 480 so that I can ensure the SD images etc.. are loading?

thanks

use the menus on your tv to change the res

Right, when I change the aspect ratio from 16:9 to 4:3 on my TV, Roku still returns true for isHD per:

Function IsHD()
di = CreateObject(“roDeviceInfo”)
if di.GetDisplayMode() = “720p” then return true
return false
End Function

Do I need to reboot the Roku or something for it to note the display change?

Did you change the output format in Roku Settings?
Just something to check.

Sorry I was wrong before. I never adjust my TV, i just change the Roku in display settings. The Roku says 16:9 and 4:3 are both SD settings, 720 and 1080 are HD obviously.
Sorry again, that was stupid.