A technique for modulating point-target infrared (IR) signatures based on the anisotropic emission behavior of the target surface is proposed. The pixel equation is used as the physical basis for quantifying the IR transmission process and is evaluated by the ray tracing method. The maximum ability to enhance and reduce signals is represented by the positive and negative maximums of the sensitivity. It is found that the modulating effects of anisotropic emission properties upon IR signals are closely related to the geometric features as well as the hemispherical emissivity. The plane is the most sensitive, while the sphere, whose sensitivity approaches zero, is the least sensitive. Furthermore, as for the nonspherical targets, the smaller the hemisphere is, the better the modulating effects are.