content: set this_file to choose file
  try
  	tell application "Image Events"
  		-- start the Image Events application
  		launch
  		-- open the image file
  		set this_image to open this_file
  		-- extract the property value
  		copy the resolution of this_image to {H_res, V_res}
  		-- purge the open image data
  		close this_image
  	end tell
  	display dialog "Resolution: " & (H_res as string)
  on error error_message
  	display dialog error_message
  end try