ActionScript 2.0 :: [FMX2004] Resize Images In Flash To Fit The Masked Area But Proportionately?

Basically I'm trying to resize images in flash to fit the masked area but proportionately....

My mask area is:

Code:
width = 478;
height = 420;

now consider that the the max width I want my pictures to be. This doesn't have to be exact. Now what I came up with to resize proportionatly is:

Code:
//width & height are my mask deminsions ( which i wanna resize my pics to)
//width_orig & height_orig are the deminsions of each new loaded pic.
height = (width / width_orig) * height_orig;
width = (height / height_orig) * width_orig;

That does scale them proportionatly but some of the times it will resize a lil bit smaller than the image area which I don't really want. Like I said this doesn't need to be exact. I would prefer it to be a lil bit bigger than the masked area. I just need to make sure the pics are scaled proportionatly.