Draw a reaction to a image using preferred size

I can export a molecule or reaction to an image file using MolExporter class, but it needs specification of desired image width and height.

Is it possible to omit this parameters or get them from somewhere else and receive an image of "pereferred" size, such size that is used when I open a chemical file in MarvinSketch itself for the first time.

 

Thank you!

Instead of dimensions (width / height) of the image, specify the scaling factor. In this case bond thickness is fix and the image size is calculated automatically. Try this setting: png:scale28

http://www.chemaxon.com/marvin/help/formats/images-doc.html