Which factor does not directly affect radiographic image density?

The factor that does not directly affect radiographic image density is ambient temperature. The image density in radiographic testing is primarily influenced by factors related to the film and the exposure conditions.

Film type plays a crucial role because different films have varying sensitivities to radiation, which can influence how much light is recorded and thus the density of the final image. Similarly, exposure time directly impacts how much radiation the film is exposed to, which is a key determinant of image density; longer exposures typically result in greater density. The distance from the radiation source also affects the intensity of the radiation that reaches the film. Increased distance results in a decrease in radiation intensity due to the inverse square law, which can lead to lower density.

Ambient temperature, while it can have some impact on the chemical reactions involved in developing the film and affecting the overall processing quality, does not directly influence the density of the radiographic image itself. Therefore, it is the least relevant factor among those listed when considering direct effects on image density.