Stop FrameMaker resizing images in DITA?

I'm using FrameMaker 12 to edit topics in DITA. Unfortunately when I add an image, FrameMaker re-sizes it. I want to stop it doing this, but I can't work out how. It looks like FrameMaker correctly reads the image size in pixels, but adds the width and height in pt not px. For example, I have a 602px by 265px image that gets added to a DITA topic as the following:

<image href = "adobe.png" height="265.000px" width="602.000px"  />