Change Image events backround color

I found a script that uses the image events application change the size of an image you drag onto the applescrip droplet and re-sizes the image to 720x486. It makes sure to keep the images height and width in ratio which is good. But the default background color for an image who’s height is greater then it’s width is white. I just need the script adjusted so the default color is black. Any ideas?

on open some_items
	repeat with this_item in some_items
		end try
	end repeat
end open

to rescale_and_save(this_item)
	tell application "Image Events"
		set the target_width to 720
		-- open the image file
		set this_image to open this_item
		set typ to this_image's file type
		copy dimensions of this_image to {current_width, current_height}
		if current_width is greater than current_height then
			scale this_image to size target_width
			-- figure out new height
			-- y2 = (y1 * x2) / x1
			set the new_height to 486
			scale this_image to size new_height
		end if
		tell application "Finder" to set new_item to ¬
			(container of this_item as string) & "scaled." & (name of this_item)
		save this_image in new_item as typ
	end tell
end rescale_and_save