Photoshop image Resolution and image size

Resolution is a measurement of the output quality of an image.They are usually referred by PPI(Pixels per inch),DPI(Dots Per Inch),SPI (samples per inch) and LPI (lines per inch).

PPI (pixels per inch) refers to screen resolution or how a monitor displays an image.PPI is used to describe the number of pixels along the height and width of an image.

DPI (dots per inch) refers to printer resolution ie how many dots of ink are placed on the page when the image is printed.Printers with higher DPI produce clearer and more detailed output.

LPI (lines per inch) is a measurement of printing resolution in systems that use a halftone screen.

SPI (samples per inch) refers to scanning resolution.

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