I need to tell that only my first attempt went well - in fact it was perfect. Every other attempt, ten or so, gave a useless result.
Sorry, I said that wrong. You can get fine results from iResizer unless you change the height... (or width, depending on motive and original dimensions). But don't think this program can resize when resizing..., if you know what I mean. 3000x2000 iresized into 1500x2000 gave a fine result, as reported, but the very same original iresized into 1200 x1600 gave a terrible result.