i often need to convert artwork and pictures to line drawings for my router projects, so i'm gonna share the procedure I use.
needed software is Gimp and the demo of Img2CAD.
first locate a picture you want to use, recently I have been making Service Branch seals so im gonna use the Air Force seal from wikpedia.
then load your pic into gimp and desaturate it and change the type to grayscale. no sense using extra memory with color if your not using it as these paths we are making can get large.
This particular emblem isnt the best to work with, and should have had the colors reduced with threshold before converting to desaturating. but you will get the idea.
Step 1: Make Into a Path
select all and pick the edge detect - Sobel
i leave everything checked, and use the preview to check if it looks correct. then apply the filter.
using the threshold adjust the black & white till you have what you want to cut and crisp lines
adjust the canvas size to about 50% larger and center the artwork
add a new layer with white so you can see the remaining lines and paths easier.
now color select the transparent area, invert the selection and use selection to path
this may take a while if the art is complicated.
make sure you save the pic often as your working on it as an .xcf (native gimp) file to save the paths.
Step 2: Rescale
select the path, select scale and set to path, and rescale to about 50% larger than original.
this can take a while, then recenter the artwork on the canvas.
now after saving you can stroke the path to a white layer, i use 2-3 pixels for this, sometimes a better result can be had from just brushing the path as a selection. Its all a matter of what your looking for, fine lines, filled areas, etc.
Now is the time to clean up any stray lines and blotches using any or all of the gimp arsenal.
When satisfied save and also save a copy as a .png file.
Step 3: Conversion to Dxf
load up Img2CAD
make sure your options are set where you need them, i use a threshold of 50 and tolerance of 1.
pick the save directory, load the .png file and click on convert.
Whoa, was it that easy? I use mach3 and lazycam, so i load lazycam, load the dxf and there it is ready to set the speeds and depth.
sometimes i will fine tune the stray lines and speckles by removing them or moving them. At least always use the cleanup function, it reduces overhead and optimizes the file. then i save the .lcam file for future use, rescale to the size i need now, set my depths, tools and speeds, and off and routing on my fireballv90.
I have gotten some spectacular results as the last pic will show you from a full color photo. carved out in 15 mins and looks great.