PDF size in px in different readers

Hello!

I'm generating a PDF with pictures and I want the pictures to have exactly a certain size in pixels (e.g. 200x200 px) on monitor when viewed from a PDF reader (when zoom is 100 %). But Adobe Reader shows PDF (and thus the picturesú bigger, i.e. with more pixels, than Foxit Reader or Nitro Reader.

Is there a way how to tell PDF readers the exact size of a page in pixels? Is there a "PDF language command" like /Resolution 300dpi? I'm using SharpPDF, which I can modify (it is open source) and Windows 7.

Here's an example:

Thanks for answers!