You could use any drawing software you have, but I usually place the image in my digitising module, be it Husqvarna 3D or Embird Studio, trace the outlines I want in the final design with a tool for outline or single stitch, then remove the original picture and use the lines as if they were my drawing, then digitise in the usual way and finally delete the 'help' lines.
What program are you using, to digitize??
Then maybe somebody will be able to help you
Hugs Yvonne