Question about @scalefit on images

[Robert D Anderson <robander@us.ibm.com>]

Hi,

A question came up in one of the DITA-OT trackers about the scalefit attribute on images. That attribute was added in DITA 1.2 as a way to state that an image should be scaled to fit the available space.

I think the assumption when adding that feature was that this would be used to scale images down to fit in an available area. With a big image and small page, scale the image down as far as needed to make it fit.

Should this attribute also be interpreted to mean that images should be scaled up? As Jarno asks in the thread below, if I have a one-quare-centimeter image but the page is 10cm wide, should the image be scaled up to fit (with resulting bad resolution)?

As an add-on to that example, what if I have a 3-inch image that fits naturally in one PDF rendering, must be scaled down for a smaller PDF page size, but could theoretically be scaled way up in an HTML browser?

I think the potential answers are either:
1. Only scale to reduce the image size, because the attribute was intended to let big images fit in small areas
2. Scale both up and down because the spec is not precise enough to prohibit it

http://github.com/dita-ot/dita-ot/issues/1727#issuecomment-54742126

Thanks,

Robert D Anderson
IBM Authoring Tools Development
Chief Architect, DITA Open Toolkit (http://dita-ot.sourceforge.net/)