Image acquisition system where target distance is determined using a fixed wide-angle camera and a second high-resolution camera

摘要

An imaging system comprising a first camera 15 with a fixed field of view (FOV) and a second camera 16 with variable FOV, wherein the distance of a target 12 from the first camera is determined by the size of the target which is nearly constant. The wide angle master camera may capture a low resolution image and the pan, tilt and zoom (PTZ) slave camera may capture a high resolution image of the target. The target may be the face or torso of a person which is approximately the same size for everyone, or other items with constant dimensions such as vehicle number plates. Co-ordinate based PTZ adjustments 19 are made using information from the master camera so the slave camera can zoom in to capture a high resolution image of the target. Multiple fixed FOVs of the master camera may require multiple registrations of the slave camera. Distance estimation using the relatively constant size of the human face makes it possible for the slave camera to quickly position and obtain images suitable for target identification.