How to replace photo background with PS in post-processing of photography

Changing the background is mainly matting. When you cut the picture, you will naturally pay attention to the retention of your hair. You can use the channel to adjust the edges, and if necessary, you can use the channel mixer to matting. After buttoning the picture, open a background picture, drag the buttoned picture directly onto the opened background picture with a mobile tool, adjust the size and position, and then adjust the details, such as color difference, illumination, light source, brightness, etc., to achieve a series of adjustments. Finally, merge the layers and save them.