1, first open the PS software on the computer, and then open the picture to be processed in the PS.
2. Next, press the shortcut key "Ctrl+j" to copy the background layer, and the subsequent operations will be carried out on the copied layer. ?
3. Next, press the shortcut key "Ctrl+L" to bring up the color code tool dialog box.
4. Then in the "Levels" dialog box, use the first eyedropper tool at the red arrow in the figure below to suck the white part of the picture, use the third eyedropper tool to suck the black part of the picture, and click "OK".