Scanning+printed+pieces

How do I scan a printed piece?
(Also see instructions on how to scan using Canon scanners)

Printed pieces (i.e. images from books, magazines, newspapers) usually contain halftone dots. When a scanner reads halftone dots, an "interference pattern" becomes visible. This is called a [|moiré pattern]. If you are scanning "real" photographs (also known as "continuous tone art"), this is usually not an issue.

To get rid of this nasty moiré pattern, follow these basic instructions:
 * 1) If your scanner has a "descreen" function, use it (but the results most likely won't be completely satisfactory).
 * 2) Scan larger than you need (2x to 4x larger is recommended). The more pixels you have to work with, the better chance of getting a decent final image.
 * 3) Blur the image: In Photoshop, use **filter > blur > gaussian blur**. Use the smallest number possible to get rid of the moiré pattern (usually .5 or 1 will work).
 * 4) Reduce the image: In Photoshop, use **image > image size** (make sure "resample image" is checked). Reducing an image will sharpen the image somewhat.
 * 5) Sharpen the image: In Photoshop, use **filter > sharpen > unsharp mask**. Recommended starting numbers (set them in this order): radius=1, threshold=2, amount=??.
 * 6) Save your file as usual (tip: to optimize the image for web publishing, use **file > save for web** and choose JPEG high; a reasonable width might be around 800 to 1000px wide).

The original scan with moire pattern visible (2x actual size)

The moire pattern is gone after blurring (2x actual size)

Reducing the image will sharpen the image slightly (2x actual size)

The unsharp mask filter will sharpen the image even more (actual size)

//Note: If you are scanning a printed piece, chances are it's copyrighted. Please respect copyright laws and "fair use" practices.//