- Image enhancement has, in general, a substantial effect on human detection performance of targets embedded in infrared images. However, different surrounding conditions such as atmospheric blur, imagery day-period, etc., cause this effect to vary. In this article, we analyze the effect of modeled histogram enhancement on human detection performance according to psychophysical experimental results. We quantify an experimental criterion for enhancement, and show that modeled histogram enhancement can considerably improve poor detection performance associated with natural images, provided that the applied enhancement method does not drastically change the natural image pixel distribution function (PDF). On the contrary, if the criterion is not achieved, modeled histogram enhancement has negligible influence.