Pool fires are open systems with steep temp., species-concn., and flow-velocity gradients, so static and dynamic radiance structures in the visible and IR spectral range are generated spontaneously. The digital image anal. of fire photograms is a valuable method of visualizing and studying static and dynamic radiance structures. Static equidensitometric structures recorded in the visible spectrum represent, in good approxn., the spatial distribution of the corresponding radiances in the IR spectrum. By applying the Abel inversion to the static radiance structures, profiles of volumetric emission coeffs. Y(r) can be detd. A simplified model, based on the assumptions of the optical thin limit and inhomogeneities in flame temps. and species concns., can be used to calc. the Y(r)-profiles. Important dynamic radiance structures, such as fire parcels, fire mushrooms, fire shapes, soot parcels, hot spots, and convection columns can be obsd. Their periodic and nonperiodic properties can be analyzed. The radiance structures studied should be considered for a more-exact modeling of fires.