About the problem of blue cloth cutout?

When taking photos in the early stage, the model should be farther away from the blue cloth to avoid projection onto it, and the blue cloth should be lit as a background. When cutting out, if you can't cut out cleanly using "Select Range", you can try the layer's remove edge command. If that doesn't work, use the blue channel to cut out. This is more complicated. If it's a camera, it's easier to do. There are special plug-ins that can cut it out more cleanly.