preTransformis a slash-separated list of TwicPics API transformations that perform before the automatic resizing of the image.

You can check the  TwicPics documentation  to see the list of API transformations.

If you set thefocusproperty, it will apply before all transformations of thepreTransformproperty.

Be aware that usingpreTransformcan lead to unexpected results, so use with caution!