grain

n.A pattern or structure in materials caused by the alignment of component fibers or particles.A design embossed on a surface to imitate a natural pattern.PhotographyThe relative coarseness of an image that results from the size of silver particles in the emulsion.

Notes

Grain3 is usually invisible to the naked eye. It becomes more visible as a negative is enlarged; prints made from small negatives are generally grainer than prints of the same size from a larger negative. Grain is generally more pronounced in high-speed emulsions.