- Studies of blooming effects in InSb focal plane array (FPA) detectors, are presented. Two blooming test devices are described, which have allowed to isolate optical, charge-diffusion and electronic blooming mechanisms. It is demonstrated that when a spurious illumination due to optical scattering is eliminated, then no extended blooming occurs, and only normal cross-talk mechanisms cause signal offset in elements adjacent to the hot target image. Cross-talk data are analyzed in terms of the signal decay versus element position, and the lateral carrier diffusion length is derived. Susceptibility of different diode structures to blooming, is discussed. It is also shown that an FPA signal processor may cause an extensive electronic blooming.