What is DPI?

Dots-per-inch (DPI) is a measure of the number of bytes created per-square-inch when converting paper to digital format through scanning.  A page scanned at 200 DPI will create a file that is 2/3 the size of a page scanned at 300 DPI.   DPI is a key consideration in controlling the size of scanned files.

Another key consideration is color setting.  Dots-per-square-inch become bits in digital format - and the number of bits required per dot, depends on color setting (black and white vs gray-scale vs color).  Black and white scanning requires the fewest 'bits' while color scanning requires the most 'bits.  This is why a color scan is larger than a black-and-white scan.  See this post to see how to calculate the size of a scanned page.

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