The coronal discharges identified as Kirlian auras are the result of stochastic electric ionization processes and are greatly affected by many factors, including the voltage and frequency of the stimulus, the pressure with which a person or object touches the imaging surface, the local humidity around the object being imaged, how well grounded the person or object is, and other local factors affecting the conductivity of the person or object being imaged. Oils, sweat, bacteria, and other ionizing contaminants found on living tissues can also affect the resulting images.