Extract Visualization JSON data

Hello,

Is there a way to extract the JSON data that is used to create a visualization? For example, I'd like to take a line graph and tweak the settings for use in existing and future reports, but as a JSON file. However, I'd like to use an existing, fully scripted file for a line graph as a starting point. If it cannot be extracted, do JSON formatted scripts exist for all the visualizations?

Thanks!