This paper presents two algorithms of feature extraction and 10 segmentation. The first algorithm is applied to detect tens of thousands of targets moving at high velocities (100's m/s) and with different sizes, velocities, shapes and directions. Upon detection, we compute statistics for each of these parameters for each particle, without any assumption nor a priori information. The second algorithm was developed to detect a 15 slow moving convective cloud. The challenge was to follow the evolution of the contours of a heterogeneous element in front of a homogeneous but possibly moving background. These algorithms were applied on images acquired with thermal cameras with different settings (frame rate, frame size, focal length, instantaneous field of view). A case study concern-20 ing images of volcanic explosive events is finally presented. Volcanoes provide, during an eruption, a source of both ballistic ejecta and a con-vective plume of finer particles, gas and entrained air both of which can be imaged in the infrared wavelength. : Results ?