I honestly think this software is brilliant and did I mention, FREE?
There are many times when using images, clipart or whatever, that we Silhouette Studio users would like to select a trace by colour but that is not possible in a lot of cases. The Studio software trace function does not trace by exact colour and cannot differentiate between say, a light blue and a light orange. So for that we need something else.
So if you wanted to cut out the heart clip art below, in its different colours, you can do that with Gimp.
You can vary the sensitivity of the selection tool, cut, copy, paste, to get the results you want. You can paste as a new selection, a new layer etc, the choice is yours.
If you want to, you can select bits and add a 'Stroke' (an outline, to you and me) to them. Simply go to 'Edit' and 'Stroke Selection' and decide how thick you want your line to be and what type of line you want.
All in all this tool is amazing. Don't forget that you adjust the properties of the tool by double click or going to the tool properties in the bar on the right of the viewing pane (the first one in the above pic, to the left of the yellow one).
Gimp will not save as SVG but you can save the pieces as PNG files in their individual colours and then simply trace the edges.
If you have not tried Gimp before, I strongly encourage you to do so. Once you get the hang of it, you'll not regret it!