Check out SW01+. There was something about tracing bitmap images.
From the help file of SW01+:
You can insert a picture onto either side of a sketch plane. Pictures are typically used as an underlay for creating 2D sketches.
Accepted file formats are .bmp, .gif, .jpg, .tif, and .wmf.
Hope that helps, Scott Baugh, CSWP
George Koch Sons,LLC
Evansville, IN 47714
sjb@kochllc.com
I routinely use bit maps for sketches. I use Corel Photo Paint but Photoshop or another photo editing software should work. What I do is open the bitmap in the photo software. I then convert the image to black & white. Next I do an auto trace of the image. If the image is very complex a manual track will be required. I then export the trace image as a DXF. Then you can insert it into SolidWorks just like any other DXF file.