I've been playing around with my laser this weekend and the one thing I can tell you is I don't think you can take a picture 'as is' and put it into any software and expect it to work very well.
You are basically taking a color picture with a large number of R, G, B, and Brightness variables and trying to convert that into an X,Y, and Z value, or in my case, a laser power value.
What I've been doing is to convert the picture to gray scale and adjusting the contrast and brightness variables to try and 'imagine' what the results will look like.
I'd suggest popping the picture into some editing software and playing with it a bit and THEN loading it into Photocarve to generate the gcode.
At least it looks like the machine is behaving nicely now and not digging into the work.
I can't tell you how many experiments I've been working on. I'll make a post on things after I get a successful image to show for myself.