Lines per inch (LPI) is a measurement of

printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ea ...

resolution. A line consists of halftones that is built up by physical ink dots made by the printer device to create different tones. Specifically LPI is a measure of how close together the lines in a halftone grid are. The quality of printer device or screen determines how high the LPI will be. High LPI indicates greater detail and sharpness. Printed

magazine A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...

s and

newspaper A newspaper is a periodical publication containing written information about current events and is often typed in black ink with a white or gray background. Newspapers can cover a wide variety of fields such as politics, business, sports a ...

s often use a halftone system. Typical newsprint paper is not very dense, and has relatively high

dot gain Dot gain, or tonal value increase, is a phenomenon in offset lithography and some other forms of printing which causes printed material to look darker than intended. It is caused by halftone dots growing in area between the original printing film ...

or color bleeding, so newsprint is usually around 85 LPI. Higher-quality paper, such as that used in commercial magazines, has less dot gain, and can range up to 300 LPI with quality glossy (coated) paper. In order to effectively utilize the entire range of available LPI in a halftone system, an image selected for printing generally must have 1.5 to 2 times as many samples per inch (SPI). For instance, if the target output device is capable of printing at 100 LPI, an optimal range for a source image would be 150 to 200 SPI. Using fewer SPI than this would not make full use of the printer's available LPI; using more SPI than this would exceed the capability of the printer, and quality would be effectively lost. Another device that uses the LPI specification is the

graphics tablet A graphics tablet (also known as a digitizer, digital graphic tablet, pen tablet, drawing tablet, external drawing pad or digital art board) is a computer input device that enables a user to hand-draw images, animations and graphics, with a spec ...

Conversion to DPI

Conversion of the LPI to the

DPI A Daytona Prototype International (DPi) was a type of sports prototype racing car developed specifically for the International Motor Sports Association's WeatherTech SportsCar Championship, as their top class of car, acting as a direct replaceme ...

is done by simple multiplication: : 150 LPI x 16 = 2400 DPI

Conversion between Lines per inch and Lines per cm

Countries using the metric system tend to use lines per centimeter (L/cm). In order to convert between L/in and L/cm the following formulas can be used: Lines per inch to lines per cm: L/cm = 0.394 x L/in i.e. 254 L/in = 100 L/cm Lines per cm to lines per inch: L/in = 2.54 x L/cm i.e. 100 L/cm = 254 L/in

References

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External links

Measuring Resolution Inch by Inch
an article about how LPI relates to DPI, SPI, and PPI Printing Units of density

Conversion to DPI

Conversion between Lines per inch and Lines per cm

See also

References

External links