How does PS remove the shadow of paper folds in photos?

there are two methods.

Method 1:

Use the patching tool (the shortcut key is J). This tool set has four tools. After selecting the repair tool, first frame the wrinkle with the mouse to generate a selection area (that is, use the selection area to select the unnatural wrinkle at the junction of color blocks), then put the mouse in the selection area, press the left mouse button and drag it to the wrinkle-free place, and PS will identify different color blocks by itself and naturally transition them.

Method 2:

A simpler method is to open the picture with the version above cs4, select the unnatural part with the selection, and press shift+f5 to open the option of color filling. The old version can fill in the foreground color, background color and pattern, etc. After cs4, there is an option of content recognition. Just click this option to confirm directly.