filmgrain
Film grain refers to the visible granular texture characteristic of many photographic films and motion-picture emulsions. It arises from the random distribution and varying size of silver halide crystals (and their development products) within the emulsion. The texture becomes more pronounced as the effective ISO increases, or as development is pushed, making grain a defining attribute of traditional film stock.
In practice, grain appears as discrete particles of varying density that can resemble salt-and-pepper noise but
Grain is often associated with the aesthetic qualities of film, contributing warmth, texture, and perceived depth.
Grain behavior is influenced by exposure, lighting, development chemistry, and printing or scanning processes. Restoration and