1. Computer Vision Center, Computer Science Department, Universitat Autonoma de Barcelona, Barcelona, Spain
2. Montreal Institute for Learning Algorithms, Université de Montréal, Montreal, QC, Canada
3. Endoscopy Unit, Gastroenterology Service, CIBERHED, IDIBAPS, Hospital Clinic, Universidad de Barcelona, Barcelona, Spain
4. École Polytechnique de Montréal, Montréal, QC, Canada
5. Imagia Inc., Montréal, QC, Canada