[luatex] howto: scaling an image

[Patrick Gundlach]

Hi,

what is the preferred strategy for scaling an external image?

When I load an image with img.new({filename=...}) I don't have access to the width/height or xsize/ysize before I turn the image into a node. Once it is a whatsit node, I have (as far as I understand) two alternatives:

1) wrap the image in a (scale_x 0 0 scale_y 0 0) matrix or
2) change the width or height and again turn the image into a node.

Which one is the preferred way?

Oh, an additional question: what are the units of the img.xsize and img.ysize table values?

Patrick