Reference

Graphic Devices ragg currently provides 4 different devices. They all share the same underlying rendering code, so the only difference is in their output formats.
agg_png()	Draw to a PNG file
agg_jpeg()	Draw to a JPEG file
agg_tiff()	Draw to a TIFF file
agg_capture()	Draw to a buffer that can be accessed directly
agg_ppm()	Draw to a PPM file
agg_record()	Capture drawing instructions without rendering