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Glad to have helped.  If your search didn't happen to turn up this thread: https://www.photoshopgurus.com/forum/photoshop-newbies/52665-need-help-getting-rid-canvas-texture.html

you may want to have a look at it.  That guy's problem was the texture of the canvas that his image was printed on, not a half-tone pattern, but the Fourier transform method works just as well for that. 

If you are not comfortable with such techniques, another possibility is to use a scanner whose software includes a "de-screening" feature.  These sort-kinda work, but never as well as applying the FT method manually.  For example, different parts of an image may require different settings.

Good luck with your project,

Tom M