There are a number of different path start generators in the Studio Artist Paint Synthesizer that support paint regionization. What this means is that the paint synthesizer analyzes your source image and then breaks it into a series of different geometric regions and paints in each region individually. This is an alternative approach to the individual 1 paint stroke at a time auto-rotoscoping capabilities of the paint synthesizer that you typically use when you press the Action button while in the paint synthesizer.
Many people are unaware that you can extend the stylistic capabilities of paint synth regionization by incorporating the Studio Artist Vectorizer into the paint regionization process. The trick to using the Vectorizer to define the regions you wish to automatically paint is to route the output of the Vectorizer into the current region selection. And to then use the ‘selection as regions- all levels’ path start generator. In version 4 you can just set the vectorizer composite option to replace the region selection. In 3.5 you would need to run the vectorizer and then set the selection to the vectorized canvas.
When working with paint synth regionization i typically use one of the paint synthesizer macros associated with regionization (like ‘auto regionize loose’) to quickly reconfigure a given paint preset to draw as a regionization process. I can then make any individual edits needed to this macro edited preset, like setting the path start generator to ‘selection as regions- all levels’ for this particular example.
The images at the top and bottom of this post show off using the vectorizer to define the regions used for paint synth regionization. The top example was using the vectorizer ‘simplify extreme’ region effect and the bottom examples was using the ‘straighten extreme’ region effect. Since the vectorizer has many different editable controls that can affect it’s stylistic output, using it in conjunction with paint synth regionization greatly increases the range of possible effects you can generate when auto-painting this way.