Tommi Mononen, Bess Hardwick, Sandra Alcobia, Adrian Barrett, Gergin A. Blagoev, Stéphane Boyer, Paula Gonçalves, Brigitte Gottsberger, Elli Groner, Chris C. Y. Ho, Marketa Houska Tahadlova, Andrea Kaus-Thiel, Irmgard Krisai-Greilhuber, Valerie Levesque-Beaudin, Carlos Lopez-Vaamonde, Sebastien Moreau, Anna Mrazova, Mikko Pentinsaari, Adrian Pinder, Kirsty Quinlan, Wolfram Remmers, Inês T. Rosário, Katerina Sam, Margarida Santos-Reis, Lucas Sire, Elise Sivault, Stefan Stoll, Patrick Strutzenberger, Lauren Vanderlingen, Fabrice Vannier, Tereza Vlasata, Otso Ovaskainen

• 1. Camera traps can generate huge amounts of images, and thus reliable methods for their automated processing are in high demand: in particular to find those images or image sequences that actually include animals. Automatically filtering out images that are empty or contain humans can be challenging, as images can be taken in different landscapes, habitats and light. Weather and seasonal conditions can vary greatly. Most of the images can be empty, because cameras using passive infrared sensors (PIR) trigger easily due to moving vegetation or rapidly varying shadows and sunny spots. Animals in images are often hiding behind vegetation, and camera traps will see them from previously unseen angles. Therefore, conventional animal image detection methods based on deep learning need huge training sets to achieve good accuracy. 2. We present a novel background removal approach based on movement masked images computed using sequences of images. Our deep vision classifier uses these movement images for classification instead of the original images. Additionally, we apply a deep active learning (active learning for deep models) for collecting training samples to reduce the number of annotations required from the user. 3. Our method performed well in singling out image sequences that actually include animals, thus filtering out the majority of images that were empty or contained humans. Most importantly, the method performed well also for backgrounds and animal species not seen in the training data. Active learning brought good separation between classes already with small training sets, without the need for laborious large-scale pre-annotation. 4. We present a reliable and efficient method for filtering out empty image sequences and sequences containing humans. This greatly facilitates camera trapping research by enabling researchers to restrict the task of animal classification to only those image sequences that actually contain animals.