Trouble getting Outline Finder filter to work in 3D Digitizing software

I have 3D Digitizing software, scanned a picture from a children's book(scanned in .tif format). Trying to apply the outline Finder filter but when I do, it turns my image into a bunch of random dots. When I use any of the images from the tutorial, the outline renders flawlessly. What am I doing wrong?

Trouble getting Outline Finder filter to work in 3D Digitizing software