is there a way to write images from render process in batch mode rendering?

Hi,

I want to save pictures from a rendering startet from command line in background mode. To save the final picture is not the problem, my question is, how to get pictures from the render process.

In gui mode I can view the iterations while blender cycles renders my scene. In background mode I only get the final result. I want to get these unsharp images, You know? Sure, I can save all these steps with growing cycles settings, but with this, the render time will grow also.

Do You have any ideas to solve this “problem”?

Thx for Your time,
Peter.