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### Scanning for printing

When scanning images for printing in papers, posters, etc., two important things to think about are pixels per inch & descreening. Pixels per inch is covered in detail on this page. Visit the page on descreening to learn more about it.

The first question to ask yourself when scanning images from a book, magazine or other print source is: How large do I want to print this image? Ideally, an image should have between 200 and 300 pixels per inch (ppi, also known as resolution or dpi) in order to be reproduced well.

#### Example

You're creating a poster for your thesis and you'd like to include an image of a painting. On your poster the reproduction of the painting will take up approximately a 3 x 5 " space. What size digital image would be ideal? Consider this calculation for an image that has a resolution of 250 ppi.

3" x 250 = 750 pixels
5" x 250 = 1250 pixels

You need an image which is at least 750 x 1250 pixels at 250 ppi.

Let's say you find a reproduction of this painting in a book, which is an 8 x 10 inch image. Scanning an 8 x 10 inch image at 250 ppi results in...

8" x 250 = 2000 pixels
10" x 250 = 2500 pixels

Great! This one will be more than big enough.

After scanning, open the image in photoshop and resize it to 750 x 1250. Or, leave the image larger than what you need (either exactly 2 or 4 times larger is ideal) and scale the image down within your document.

Remember: better to start with an image that is too big than too small, you can downsize later.