photoshop - What is the best way to remove texture from a scanned textured photo paper?

I have a bunch of scanned old family photos where the photo paper has a texture. Unfortunately, the texture of the photo scans quite well. What is the best way to remove the texture? (Photoshop CS5)

Answer

The textbook method is, as others mentioned, to suppress the texture in frequency space. I will explain how to find the correct filter, that you can basically do manually in ImageJ (freeware java app). When you open the program it is a strip of menu. The parts you need are:

• File Open


• Selection rectangle


• Edit Crop


• Process-> FFT -> FFT


• Process-> FFT -> Inverse FFT


• Paintbrush (with black color)

First, load your image. Then select the part that's only white with texture. Do FFT on this crop:

You now notice a star pattern. This is the pattern to recognize when you open the image again, and do FFT on the whole thing:

Now, don't remove the center point as that is the "DC" value. Which means the average brightness. Use the paintbrush to eliminate the other stars. Make the black points big enough but not too big (play around with it). If you overdo it, you will get banding around the edges and borders.

Now do inverse FFT:

(Note: You need to have the FFT image window selected when you try to do the inverse FFT. If you have the original image window selected, you'll get an error saying "Frequency domain image required".)

And if you can do this at higher resolution than you need, you can downsize the image with lanczos resampling for an even better result:

If you know some scripting or programming you could impose this elimination pattern automatically on an entire set.