Putting Context into Vison把语境分为视觉.pptVIP

Putting Context into Vision Derek Hoiem September 15, 2004 Questions to Answer What is context? How is context used in human vision? How is context currently used in computer vision? Conclusions What is context? Any data or meta-data not directly produced by the presence of an object Nearby image data What is context? Any data or meta-data not directly produced by the presence of an object Nearby image data Scene information What is context? Any data or meta-data not directly produced by the presence of an object Nearby image data Scene information Presence, locations of other objects How do we use context? Attention Are there any live fish in this picture? Clues for Function What is this? Clues for Function What is this? Now can you tell? Low-Res Scenes What is this? Low-Res Scenes What is this? Now can you tell? More Low-Res What are these blobs? More Low-Res The same pixels! (a car) Why is context useful? Objects defined at least partially by function Trees grow in ground Birds can fly (usually) Door knobs help open doors Why is context useful? Objects defined at least partially by function Context gives clues about function Not rooted into the ground ? not tree Object in sky ? {cloud, bird, UFO, plane, superman} Door knobs always on doors Why is context useful? Objects defined at least partially by function Context gives clues about function Objects like some scenes better than others Toilets like bathrooms Fish like water Why is context useful? Objects defined at least partially by function Context gives clues about function Objects like some scenes better than others Many objects are used together and, thus, often appear together Kettle and stove Keyboard and monitor How is context used in computer vision? Neighbor-based Context Markov Random Field (MRF) incorporates contextual constraints Blobs and Words – Carbonetto 2004 Neighbor-based context (MRF) useful even when training data is not fully supervised Learns models of ob