DPI

• DPI stands for dot per inch.
• DPI is used to measure the resolution of an image both on screen and in print.
• It measures how many dots fit into a linear inch.
• Higher DPI gives better resolution.

DPI in printing

• In printing, DPI is the usual measure of printed image quality on the paper.
• The average personal computer printer today provides 300 DPI to 600 DPI.
• Higher print quality usually reduces the speed of printing each page.
• Higher DPI produce clearer and more detailed output.

DPI in computer monitor

• In computer monitors, DPI measure the sharpness on a display screen.
• The dot pitch determines the absolute limit of the possible dots per inch.
• The dots per inch for a given picture resolution will differ based on the overall screen size since the same number of pixels are being spread out over a different space.

Calculation of DPI

• To calculate the horizontal DPI divide the width in pixels by the picture size in inches.
• To calculate the vertical DPI divide the height in pixels by the picture size in inches.

For example:  Below the given picture if you like to print in size 8 inch * 4 inch then

Horizontal DPI = 640 pixels / 8 inch = 80 DPI
Vertical DPI = 404 pixels / 4 inch = 101 DPI

My notes