Even though Illustrator is the king of vector artwork, it can also play nicely with raster, as you’ve seen. In my experience, I’ve found that the bulk of the image editing should be done in your image-editing program (like Photoshop), but artistic effects, scaling, and masking can all be done in Illustrator.
To learn more about the working with raster images in Illustrator, check out these resources:
- Adobe Illustrator CC 2014 Classroom in a Book
- My YouTube channel