VS3D can import color and gray-scale images, converting image brightness to surface height. However, the height values stored internally (and output) by VS3D are floating-point (decimal).
One question you might want to consider is what do you want to do to the surface after importing an image, and before cutting it ? The whole point of VS3D is to provide Virtual Sculpting tools to free-form sculpt any relief surface (regardless of whether it came from a digital photograph or other source). This free-form sculpting can include hammering, smoothing, flattening, bulging, chiseling, etc.
VS3D is set up in such a way that the sculpting is performed close to real time. For example, if you click the hammer tool on the surface, you will immediately see the dent you just made. Many other CAD programs, when working on a highly-detailed surface, have a delay between the user action and visual feedback. But to be a successful tool for a sculptor to use, there can not be a delay since hammering and scraping operations need to look like you are doing it in real clay right before your eyes. To get this type of performance, it is necessary to align the view looking straight down on the surface. But VS3D has an ancillary tool, VScad3, which can be used to view (and rotate) a relief surface in 3D space.
The general style of the VS3D user interface is mathematical in nature. This allows the interface to be visually simple, yet extremely flexible.
Below is an example of a fantasy coin I just made by sculpting it in VS3D. I started out by doing a pencil drawing. I then scanned the sketch and imported it as a tif image into VS3D and used the sculpting tools to fill it out. I ran the resulting VS3D G-code on an S&W Engineering mill to engrave the 38mm diameter steel stamping dies. The coin was then stamped in pure copper and given an antiqued finish: