  For large scale applications, hybrid pixel detectors, in which sensor and
read-out IC are separate entities, constitute the state of the art in pixel
detector technology to date. They have been developed and start to be used as
tracking detectors and also imaging devices in radiography, autoradiography,
protein crystallography and in X-ray astronomy. A number of trends and
possibilities for future applications in these fields with improved
performance, less material, high read-out speed, large radiation tolerance, and
potential off-the-shelf availability have appeared and are momentarily matured.
Among them are monolithic or semi-monolithic approaches which do not require
complicated hybridization but come as single sensor/IC entities. Most of these
are presently still in the development phase waiting to be used as detectors in
experiments. The present state in pixel detector development including hybrid
and (semi-)monolithic pixel techniques and their suitability for particle
detection and for imaging, is reviewed.
