If you need to export PDF to an image file for any reasons, I recommend you to use PDF-XChange Viewer. This is a great software and I have even thought to purchase a Pro version.
In order to convert your PDF file, you need to perform the following steps:
1. Download the program (I’m using portable version, it doesn’t require to install anything). The most recent version at the moment is 2.5.205.
2. Extract the portable version to a folder and run an exe file. Here is how its interface looks like:
3. Load your PDF file.
3. Press File->Export->Export to Image
4. Modify any parameters you need and press “Export” button.
If you know any easier method to export PDF to images format, let me know.