Spatial frequency refers to the rate of change of intensity or color in an image or pattern across space. It is an important concept in the field of image processing and computer vision, as it can be used to analyze and characterize various visual patterns and textures. Spatial frequency analysis involves measuring the frequency of changes in an image at different scales, with high spatial frequency indicating rapid changes and low spatial frequency indicating gradual changes. This analysis can be applied in various fields such as image compression, pattern recognition, and medical imaging for tasks like edge detection, texture analysis, and feature extraction.