Often on forums and sometimes on blogs, you will see people mixing up DPI and/or PPI and they use it interchangeably. They are wrong.

1. DPI = Dots Per Square Inch
2. PPI = Pixels Per Square Inch

So what's the difference between the DPI vs. the PPI.

• The DPI is always used for output devices such as screens, printers, projectors...
• The PPI is always used for input devices such as the CCD/CMOS in cameras, sensors...

To muddy the waters, somewhat, inkjets and laser printers use DPI while offset printers and line printers use LPI, Lines Per Inch.

1. Currently, 2009, all pixels are black or white. Then each pixel is assigned to the correct RGB¹ via filters. The usual proportion of the pixels assigned to a color is: 1 Red, 2 Green, and 1 Blue pixel. But this will vary by sensor manufacturer.
2. All dots are made of multiple colors. How many colors will make the dot will depend on the output device. Screens only use 3 colors, the RGB. Printers use as many colors as they have color tanks, cartridges to make their dots.

¹ Red, Green and Blue ↑

Tags: Technical