Dots per inch (DPI) is a measure of printing resolution, in particular the number of individual dots of ink a printer or toner can produce within a linear one-inch (2.54 cm) space. For other uses, see Print. ...

Close-up of dots produced by an ink-jet printer. ... Inkjet printers are a type of computer printer that operates by propelling tiny droplets of liquid ink onto paper. ...

DPI measurement

Up to a point, printers with higher DPI produce clearer and more detailed output. A printer does not necessarily have a single DPI measurement; it is dependent on print mode, which is usually influenced by driver settings. The range of DPI supported by a printer is most dependent on the print head technology it uses. A dot matrix printer, for example, applies ink via tiny rods striking an ink ribbon, and has a relatively low resolution, typically in the range of 60 to 90 DPI. An inkjet printer sprays ink through tiny nozzles, and is typically capable of 360 DPI. A laser printer applies toner through a controlled electrostatic charge, and may be in the range of 600 to 1800 DPI. A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper transparencies]]. Many printers are primarily used as computer peripherals, and are attached by a printer cable to... A dot matrix printer or impact matrix printer refers to a type of computer printer with a print head that runs back and forth on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like a typewriter. ... Inkjet printers are a type of computer printer that operates by propelling tiny droplets of liquid ink onto paper. ... 1993 Apple LaserWriter Pro 630 laser printer A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. ... A color toner bottle Toner is a powder used in laser printers and photocopiers to form the text and images on the printed paper. ...

The DPI measurement of a printer often needs to be considerably higher than the pixels per inch (PPI) measurement of a video display in order to produce similar-quality output. This is due to the limited range of colours for each dot typically available on a printer. At each dot position, the simplest type of colour printer can print no dot, or a dot consisting of a fixed volume of ink in each of four colour channels (typically CMYK with cyan, magenta, yellow and black ink). Contrast this to a standard sRGB monitor where each pixel produces 256 intensities of light in each of three channels (RGB) to additively create 256³ = 16,777,216 colours. The number of unique colours for a printed CMYK dot from this simplest type of inkjet printer is only 8 since no coloured ink is visible when printed on black and black is used instead of CMY: The square shown above is 200 pixels by 200 pixels. ... Cyan, magenta, yellow, and key (black) CMYK (or sometimes YMCK) is a subtractive color model used in color printing. ... Cyan (from Greek κυανοs, meaning blue) may be used as the name of any of a number of a range of colors in the blue/green part of the spectrum. ... Magenta is a color made up of equal parts of red and blue light. ... A yellow Tulip. ... This article is about the color. ... The title given to this article is incorrect due to technical limitations. ... REDIRECT RGB color model ... Additive color mixing: adding red to green yields yellow; adding yellow to blue yields white. ...

• white (no ink)
• cyan
• magenta
• yellow
• blue = cyan + magenta
• green = cyan + yellow
• red = magenta+yellow
• dark brown (not used) = cyan + magenta + yellow
• black

While some colour printers can produce variable drop volumes at each dot position, and may use additional ink colour channels, the number of colours is still typically less than on a monitor. Most printers must therefore produce additional colours through a halftone or dithering process. The exception to this rule is a Dye-sublimation printer that utilizes a printing method more akin to Pixels per inch. White is the combination of all the colors of the visible light spectrum. ... Cyan (from Greek κυανοs, meaning blue) may be used as the name of any of a number of a range of colors in the blue/green part of the spectrum. ... Magenta is a color made up of equal parts of red and blue light. ... A yellow Tulip. ... The term blue may refer to any of a number of similar colours. ... Leafy green fountain in Wattens, Austria. ... For other uses, see Red (disambiguation). ... The brown and orange disks of color are objectively identical, in identical gray surrounds, in this image; their perceived color categories depend on what white they are compared to. ... This article is about the color. ... Left: halftone spots. ... This article or section should be merged with Dither An illustration of dithering. ... Samsung SPP-2040 working. ... The square shown above is 200 pixels by 200 pixels. ...

The printing process could require a region from four to six dots (measured across each side) in order to faithfully reproduce the color contained in a single pixel. An image that is 100 pixels wide may need to be 400 to 600 dots in width in the printed output; if a 100×100-pixel image is to be printed inside a one-inch square, the printer must be capable of 400 to 600 dots per inch in order to accurately reproduce the image.

Image File history File links Conceptual comparison of pixels per inch and dots per inch. ...

Misuses of DPI measurement

Owing in part to its conceptual similarity with other measurements of graphical resolution, the DPI measurement is frequently misused. For instance, it is common for an image scanner's sampling resolution to be specified in terms of DPI, though a more accurate measurement would be samples per inch. The number of pixels per inch in a computer display is sometimes specified in this way as well. Usage of the DPI measurement in these cases is inaccurate and misleading, though the intended meaning is usually clear based on context. In computing, a scanner is a device that analyzes images, printed text, or handwriting, or an object (such as an ornament) and converts it to a digital image. ... A sample refers to a value or set of values at a point in time and/or space. ... Samples per inch (SPI) is a measurement of the resolution of an image scanner, in particular the number of individual samples that are taken in the space of one inch. ... The square shown above is 200 pixels by 200 pixels. ... A computer display monitor, usually called simply a monitor, is a piece of electrical equipment which displays viewable images generated by a computer without producing a permanent record. ...

An example of misuse of the DPI scale would be if an LCD monitor manufacturer claimed that a 1280 x 1024 resolution monitor actually had a resolution of 3840 x 1024, (three times the resolution), because each pixel was made of three colored dots, (Red, Green and Blue). Technically they would be correct but compared to the standard accepted practice of using whole pixels as a means to measure resolution a customer may be confused into thinking the monitor relabelled as 3840 x 1024 had a greater resolution and therefore better picture quality when in fact it would be exactly the same as standard labeled monitors. This misuse is generally found in advertising for in-car LCD displays.

Proposed alternative measurements

There are some ongoing efforts to abandon the DPI in favor of giving the inter-dot spacing in micrometres (µm).^{[citation needed]} This is however hindered by leading companies located in the USA^{[citation needed]}, one of the few remaining countries not to use the metric system exclusively. A resolution of 72 dpi for example equals an inter-dot spacing of about 350 µm, 96 dpi → 265 µm, 160 dpi → 160 µm, 300 dpi → 85 µm, 4000 dpi → 6.4 µm. Going the other way, 1 µm → 25400 dpi, 30 µm → 850 dpi, 200 µm → 127 dpi. Note that 25400 = 1 dpi·µm, so dividing 25400 by a measurement in one of these units gives the measurement in the other unit. A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... Cover of brochure The International System of Units. ...

Some have also proposed using dpcm (dots per centimetre). Dots per centimetre or dpcm is a unit of resolution, used as a metric alternative to dots per inch/dpi. ...

Computer monitors are universally rated in pixel pitch. Dot pitch (sometimes called line pitch or phosphor pitch) is a specification for a computer display that describes the distance between phosphor dots (sub-pixels) or LCD cells of the same color on the inside of a display screen. ...

See also

• Pixels per inch
• Samples per inch
• Lines per inch
• Metric typographic units
• Display resolution
• Mouse DPI

The square shown above is 200 pixels by 200 pixels. ... Samples per inch (SPI) is a measurement of the resolution of an image scanner, in particular the number of individual samples that are taken in the space of one inch. ... Lines per inch (LPI) is a measurement of printing resolution in systems that use a halftone screen. ... Most desktop publishing software, coming from the US, such as PageMaker and QuarkXPress and Adobe InDesign, uses the PostScript point as the unit of measurement for typography. ... Display standards comparison The display resolution of a digital television or computer display typically refers to the number of distinct pixels in each dimension that can be displayed. ... There are very few or no other articles that link to this one. ...

External links

• All About Digital Photos - The Myth of DPI
• Say No to 72dpi