How to get jpg/tiff figures with

1. Edit figures in PPT
2. Save as PDF
3. Open PDF in Xchange PDF viewer
4. Crop marginal

5. Export file to image:
   

   5.1 choose formate, set DPI: image.png , one can preview the pixel on the right hand side.

5.2 tune zoom to get the proper size in (pixel or cm): One could make use of online tool to calculate the pixel to export https://www.pixelto.net/px-to-cm-converter

6. Export Image.