[R] Surprise when mapping matrix to image

[Liaw, Andy]

> From: Richard A. O'Keefe
[snip]
> Given the wide range of ways that the x, y, z arguments can be passed
> to image(), it would actually make sense to have some kind of 
> flip and/or
> mirror operations specified via an argument to image().
> The source code of image is available (image.default) so it 
> wouldn't be
> a lot of work for someone who wants it to produce such a thing.

I'd suggest adding an `as.matrix' argument to image.default.

Best,
Andy