geocoding, get corner latitude longitude

I have some x/y point of an image, this points corresponds to latitude/longitude values, i开发者_Go百科f I know the size of the image how to calculate(in java) image corners latitude/longitude? thanks

• take the scale
• check if lon at y = l1 then what would it be at y = cornerY
• check if lat at x = l1 then what would it be at x = corner