First, open the picture to be operated in ps, as shown in the figure below.

Click "Image", "Adjustment" and "Color Scale" in turn, as shown in the following figure.

Third, the color scale setting box will pop up, as shown in the figure below.

4. Change the values in the box below the figure to "60", "1.00" and "200" in turn, and click OK, as shown in the figure below.

5. At this point, the background of the picture will become a white background, as shown in the figure below.