Graphic Scaling Percent

I am importing PDF pages into FrameMaker. I want to do some scaling in ExtendScript, but I can't see where the Scaling % that is shown in the interface is exposed to ExtendScript. I see these properties in the FDK documents:

#define FP_OriginalHeight 2381 /*R/O Metric*/
#define FP_OriginalWidth 2382 /*R/O Metric*/
#define FP_OriginalDpi 2397 /*R/O Int*/

but the equivalent OriginalHeight, OriginalWidth, etc. properties don't appear to be exposed to ExtendScript.