I think you want the "Hidden Lines Removed" view. As opposed to "Shaded" or "Shaded with Edges" views. The other display styles Solidworks has is "Hidden Lines Visible" and "Wireframe".
I do not know if any of the SW add-ins can do this directly.
If I needed to do this for a project I would save out the "hidden lines removed" image, then open this in a software editing package. There you could set the white portions to be transparent and save the new image.
As far as I know Solidworks will not produce transparent regions of images, every pixel is given a color when saving images.
thanks for your posting. In the moment you wrote about editing package I rememered that a .svg file can be opened in Adobe Illustrator. This file can than be exported as .png where the transparency can be selected and it looks as following. Thus can easily be used for adobe indesign.
This discussion as short as it was really helped me to find the solution.
It would be good to move this thread to the SolidWorks Composer sub-forum if this is a Composer question. You can use the Move link up in the upper right sidebar.
For SolidWorks you can use PV360 rendering.
Using PhotoVIew 360 with a plain white background and the new Cartoon shading options will get you what you need.
I am sorry I tried to move but I am not able to find the solidworks composer forum. I really thought I was already in it. Sorry, is there any way that someoneelse moves this discussion.