White backgrounds are used for presentation on ecommerce websites (contextual backgrounds when showing a product in use). Even if you can photograph to pure white at the edges of a photo, it will transition to grey around the object and pieces will almost always have some fuzzy edges. While there are automated edge-detection tools in editors like Photoshop or GIMP, they do not give clean edges like this. So professionals do this job using a vector-editing tool. In the past this implied learning the path tool (e.g. inPhotoshop) but now inexpensive phone apps can do it well. On the lower left is the original image (already cropped). On the lower right I have it open in an iOS app named Exacto. The blue dots are stationary anchors and the black ones pull out curves between them (curves flow smoothly through the black ones). By zooming and add/moving dots I can produce these crisp edges (Exacto saves it to iOS Photos with a transparent background). Notice how clearly the clean edges enhance the throwing rings on the right.
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