How ps makes the white spot corrosion effect of yellowing old photos

Ps produces the white spot corrosion effect of yellowed old photos in the following ways:

1. Search for "old paper" on the Internet and find the image that meets your requirements.

2. Open the original image with PS.

3. File-Insert-Insert the image of "old paper".

4. Adjust the size to be consistent with the original size.

5. Adjust the opacity of the layer.