Abstract: The concept of linear algebra is complex and practical. It is widely used in many fields. The introduction of matrix theory into linear algebra in image processing is the most widely used and the most concerned area in the society. At present, image processing is realized by computer. In computer, image is mainly composed of several "continuous" pixels. However, in essence, there is no actual connection between pixels, but the distance is very close, which can not be detected by human eyes. In the field of mathematics, people often say that image pixels are similar to matrix elements in linear algebra in essence, so when processing images, matrix can be used for representation. Based on this, the well-known matrix theory in linear algebra is widely used in image processing.