Can I convert .png graphics to .pes format?
It should be fairly straightforward converting Portable Network Graphics directly to Brother PE Embroidery Format (.png to .pes conversion).
There are a several dedicated embroidery programs, such as BuzzXplore or SewArt, which will allow you to create PES embroidery designs from PNG graphics.
The more complex the source image is, the less successful the transformation will be (or the resulting representation of the original will much poorer). It is, typically, easier to make embroideries from simple images that contain fewer colors.
An embroidery designs manager
An embroidery digitizer