BASAR Forum

Sattva Descreen plugin is available for Photoshop and Affinity Photo. It cleans up the halftones used in nearly all printed artwork.

http://www.descreen.net/eng/soft/descreen/descreen.htm

It does cost some money, but it is one of the best purchases I have made....I can't imagine not descreening a scan anymore...they look horrible in raw form
Halftones are a way for printing companies to get a desired effect, while overcoming the limitations of mass printing and lowering the amount of ink required to print a design. When viewed from a distance by human eyes, the colors look correct and fade into each other. But when scanned at high resolution the effect is very noticeable. And when a computer tries to rescale an image with halftones it causes noise to show up in the image as well pattern interference that can create moire effect.

And because halftones are created by making varying amounts of color separated by white space, the image codec has to account for all those changes in contrast. So a descreened image also ends up being much smaller in file size since the colors now all blend together.

Here is file size comparision showing an 800DPI image and then a 1000x1000 cover version.
Here is what halftones look like up close
Comparison of raw scan versus descreen.

(click to see full size images)

Raw scan @ 800 DPI
Descreened Scan @ 800 DPI

When you open the Descreen plugin, you will get a preview window and the plugin will try to automatically determine the halftone pattern. If it can't find it, try dragging the preview window around to an area with better coverage. You can also toggle the automatic button to make it try to recalculate.