From time to time, you may be called upon to scan something that was printed in a newspaper. It may be an article for your boss or a picture for use in PowerPoint.
Newsprint offers a unique set of challenges. The web fed 4 colour process that is employed in newsprint softens images and flattens colours. Added to this is a moire pattern that is made from the screens used to print each colour.
This scan comes from an article sent to me by my cousin, Michael MacFarlane (pictured in the photo). The article is promoting the 2009 Scottish Homecoming. The Gathering in 2009 will be the largest clan get-together in Edinburgh since Sir Walter Scott's Pageant of 1822. As a retired caber toss champ, I can't wait for this historic event and plan to bring the whole family.
Back to the image.
In setting up the image in your scanner's software, scan the image in at 150%-200% of what will be required for your final output size (but don't exceed the limit of your scanner's optical resolution).
Initially, we see an image that is flat and a bit soft. Our first instinct is to refocus the image. But with newsprint, try a touch of Gaussian Blur first, Filter>Blur>Gaussian Blur. This will tighten up the image and remove most of the moire. From there, we can resume our usual workflow. We will be doing creative sharpening and output sharpening, so don't worry so much about the refocus step.
Try just a touch of Gaussian Blur, a radius of 1 or less. Modern printing presses achieve higher line screens than some of the older presses. If you can see a pronounced dot pattern, you may need to use a radius of 1.5 or so. Subtle patterns can be removed with a radius of around .5. For this image, I used a radius of .5. For an more subtle effect try using the Median filter, Filter>Noise>Median, with a radius of between 1-3.