What is DPI?
For a complete DPI guide including image samples and suggested uses, download our DPI guide here.
DPI, or dots per inch, relates to the concentration of color dots used anywhere an image is displayed in pixels or dots. Essentially, a higher DPI yields a higher image resolution. DPI is also important in retaining quality when resizing an image. The concept of DPI can get pretty complicated across varying media forms but for this post we'll concentrate on DPI in the context of document imaging. When scanning documents, DPI becomes important for the following reasons:
Image/Print Quality
- You should get picky with DPI if you're scanning images that will need to be printed in a high quality later on. For simple text documents, a lower DPI will suffice, but for scans from magazines or photographs, a high DPI will be essential to the print quality of those images. A high DPI is also necessary to make your document text-searchable. DPIs of 200 or higher make text recognition available.
File Size
- If high print resolution isn't a priority, the concerning effect of DPI is file size. The lower the DPI, the lower the size of your digital document. If your scanned documents are just text, you can be less concerned with image quality, and more concerned with document size to save time and disk space. Also, if your document is going to be viewed on a computer screen and not re-sized, there is no need to scan at a DPI any higher than a computer screen (average computer screens are typically 96 DPI or 76 with older models). Lower file sizes are easier to send over networks and can be uploaded quickly.
DPI Yields:
72 - 100
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Computer screen viewing only
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Low Quality Printing
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Small File Size
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Text Document Sharing (*not text-searchable)
200
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Good compromise between file size and resolution.
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Web Content
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Text Searchability
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Medium quality printing
300
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Max necessary DPI
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Near exact copy of original image
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High Resolution Photo-Printing
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