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PPI, DPI vs a sensor PPI
Mar 13, 2021 13:32:37   #
Rongnongno Loc: FL
Pixels terminology is confusing.

Pixels are created two ways:
→ Sensor (camera, fax, light sensitive imaging equipment)
→ Software

Once created a pixel is a mathematical formula that will represent a color shade. It does not have a size. It has a value.

When an image is used it is represented by 'pixels' on a device or media.
→ Each 'pixel' can represent many pixels using 'interpolation'.
→ Many 'pixels' can represent a single pixel using 'extrapolation'.
→ A monitor or screen is then defined as 'Pixel' Per Inch (PPI).
→ A printer's capabilities are described with Dot Per Inch (DPI).

The difference between monitors and printers output is simple:
→ 'Pixels' displayed on a monitor are dynamic.
→ A printer output is static.

PPI and DPI are a bit confusing as they are basically interchangeable as long as the output device is not identified.

Then there are the (camera) sensors marketed as PPI. Using Sensor Per Inch (SPI) instead of PPI to describe a sensor array's resolution would have solved the confusion issue once and for all.

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