In vivo and in situ confocal images are often distorted by motion artifacts and soft tissue deformations. To measure small amplitude phenomena on this type of images, we have to compensate for those artifacts. We present in this paper a Region Of Interest (ROI) tracking algorithm specialized for confocal imaging using a scanning device. Two different algorithms are presented: one based on the motion artifacts, and one based on affine registration. One typical application of this tool is developed: the blood velocity estimation inside a capillary on a moving organ. These first results show that the method permits accurate estimations of blood cell velocities even in presence of motion artifacts.