Comment 2 for bug 392999

Hi Juho,
Thanks for your work.
- Could you use the standard lib optparse.OptionParser to parse the values, which Phatch uses? That allows defaults and type conversions. For an example see phatch/app.py
- Please use Fields and don't introduce options. As said before this action should be implemented as the imagemagick action for now. The reason is that in the next release all Imagemagick and Blender actions will be independent actions, next to the pil actions. So I prefer that both Imagemagick and Blender follow the same approach for now.
- I'll look into providing a FloatSliderField. So for now you can use a FloatField or SliderField, as you did now.