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In image resolution, whats the difference between 400 dpi true and 400 dpi interpolated?

April 26, 2017DPI image interpolated resolution

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In image resolution, whats the difference between 400 dpi true and 400 dpi interpolated?

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True resolution is the number of dots per inch of reflected light captured by the scanner head. The scanner head is physically limited in the number of dots which it can capture. Interpolation software (usually built in to the scanner, but also available in raster manipulation programs) can make a good guess at what lies between the dots recorded by the scanner. By comparing adjacent dots captured in a true 200 dpi scan interpolation software might replace each dot with four new ones (creating a 400 dpi interpolation) or even nine new ones (creating a 600 dpi interpolation). For many applications (including the majority of paper to CAD conversions) interpolation works well. But interpolation will never be as accurate as a true resolution.