This does the following :
- opening a distant image file with AJAX request, using
pixpipe.UrlImageReader
- Computing the closest internal polygon from a seed with
pixpipe.ContourHolesImage2DFilter
- Printing the polygons on top of a copy of the input image with
pixpipe.LineStringPrinterOnImage2DHelper
- Displaying it in a canvas using
pixpipe.CanvasImageWriter