So what is the required resolution of my photos?

Pixels per inch (PPI) or dots per inch (DPI) are both the same. Our computer screens will illustrate a 72 ppi photo sharply. I can just see the prepress technician cringe when they hear “it looks good on my screen”. The higher the ppi/dpi the larger the file. For example a 4x5 - 72 ppi photo could be 500 kb, the same photo at 300 ppi can be 5 megabytes.

We recommend 300 ppi for all photos at the same size as they are going to appear in your digital file. For example if you take a 4 x 5 inch 300 ppi photo and enlarge it 3 times, the information will be divided by 3. So your 12 x 15 inch photo will be 100 ppi. The 100 ppi photo will appear jagged on the high resolution output.

 

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The photos below (Left = high res • Right = low res) illustrate the difference.

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Most digital cameras shoot at 72 ppi, the camera increases the physical size of the photo for more information. (A small file setting will be 4x5”-72 ppi, medium will be 8x10”-72 ppi and large 16x20”-72 ppi). The reasoning behind this is the larger the file size the more information stored. Then by reducing the physical size of your “Large” 72 ppi file, you would also compress the pixels per inch (adding information and detail). For example by reducing the 16x20” 72 ppi file 4 times to a 4x5” the ppi is compressed (4x72=288) to about 300 ppi (acceptable high resolution). Just consider the lower the ppi/dpi number the bigger the pixels will be (as illustrated above - on the right). This information also applies to your scans. If you scan at 72 ppi/dpi the image will have to be reduced 4 times to equal 300 dpi/ppi. Feel free to contact our prepress with any questions you have.