How to change DIU width/height of a png image

Hi,

I have a png image of 1275 X 1650 resolution and 32 bit depth, but when it is loaded in BitMapImage its Width & height are returned to a very low value 408 X 528. I have a similar png image of same resolution and bit depth but it returns a higher Width & Height (816 X 1056) after it is loaded in BitMapImage object. Can you please tell how/what to change in the png image to get a better Width & Height after it is loaded in BitMapImage class.

Regards,

R.Sundar