What is the term for the loss of resolution, edge sharpness, and clarity in an image?

The term that best describes the loss of resolution, edge sharpness, and clarity in an image is diffraction. This optical effect occurs when light waves pass through a small aperture or around an obstacle, causing them to spread out. As a result, the finer details and edges of the subject may become less sharp, leading to a noticeable decline in image quality. This phenomenon is particularly evident in images taken with small apertures, where the sharpness can be diminished as light interacts with the edges of the aperture blades.

In contrast, while chromatic aberration involves color fringing at the edges of objects due to different wavelengths of light not focusing at the same point, and vignetting refers to a gradual darkening of the corners of an image compared to the center, these issues do not specifically describe the general loss of resolution and clarity. Noise, typically associated with unwanted graininess in images, often results from high ISO settings or low-light conditions, which also differs in nature from the effects of diffraction.