question: Why is the standard resolution for printing 300 dpi ?
comment: The original Apple LaserWriter had 1.5MB of memory, a large amount for 1985. 300dpi requires 1MB for the frame buffer of an A4 or US letter page. So there are was strong pressure to minimise the resolution to keep the device affordable. 300dpi is pretty good for text and line art. Its main issue was for shades of grey as in photos or other graphics. If you want 256 shades, as with a computer monitor, you need at least an 8 & times;8 halftone grid. Dividing 300 by 8 gives only a very coarse 38 lines per inch halftone resolution. Making good, fine halftones for photos is the main driver for the 2540dpi used by professional printers.
passages: This dithered printing process could require a region of four to six dots (measured across each side) in order to faithfully reproduce the color 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 in a one-inch square, the printer must be capable of 400 to 600 dots per inch to reproduce the image. Fittingly, 600 dpi (sometimes 720) is now the typical output resolution of entry-level laser printers and some utility inkjet printers, with 1200/1440 and 2400/2880 being common "high" resolutions. This contrasts with the 300/360 (or 240) dpi of early models, and the approximate 200 dpi of dot-matrix printers and fax machines, which gave faxed and computer-printed documents—especially those that made heavy use of graphics or colored block text—a characteristic "digitized" appearance, because of their coarse, obvious dither patterns, inaccurate colors, loss of clarity in photographs, and jagged ("aliased") edges on some text and line art.
   The measures dots per inch (dpi) and pixels per inch (ppi) are sometimes used interchangeably, but have distinct meanings, especially for printer devices, where dpi is a measure of the printer's density of dot (e.g. ink droplet) placement. For example, a high-quality photographic image may be printed with 600 ppi on a 1200 dpi inkjet printer. Even higher dpi numbers, such as the 4800 dpi quoted by printer manufacturers since 2002, do not mean much in terms of achievable resolution.
   However, for printing technologies that perform color mixing through dithering (halftone) rather than through overprinting (virtually all home/office inkjet and laser printers), printer DPI and image PPI have a very different meaning, and this can be misleading. Because, through the dithering process, the printer builds a single image pixel out of several printer dots to increase color depth, the printer's DPI setting must be set far higher than the desired PPI to ensure sufficient color depth without sacrificing image resolution. Thus, for instance, printing an image at 250 PPI may actually require a printer setting of 1200 DPI.
   Early laser printers from the late 1970s onward could also generate halftones but their original 300 dpi resolution limited the screen ruling to about 65 lpi. This was improved as higher resolutions of 600 dpi and above, and dithering techniques, were introduced.
   Section::::DPI measurement in printing.:DPI or PPI in digital image files.
  
  In printing, DPI (dots per inch) refers to the output resolution of a printer or imagesetter, and PPI (pixels per inch) refers to the input resolution of a photograph or image.
   Printers are generally referred to as "Super-Wide format" when their print bed exceeds 2.2m in width. For many applications at this size resolution becomes secondary to print speed - which is why many machines over 3m wide are designed for speed over resolution. In the 1980s billboards were generally printed at resolutions as low as 80dpi (dots per inch). Resolutions today are much higher because of the improvements in technology but printing billboards, vehicle graphics, building wraps and the like do not require the ultra-high resolutions of 1440dpi and upwards often associated with standard wide format printers. It is normal for super-wide format digital printers to function at maximum resolutions of between 540dpi and around 1040dpi. However even these resolutions are rarely used in a production environment, billboards and building wraps for example are often done at between 200dpi and 350dpi and the end result relies on the viewing distance for the impactful, colourful graphics the public sees on roadsides and buildings. The fact that they are capable of printing at these higher resolutions is still important though because it attests to the size of the ink droplet being laid down by the inkjet solvent and eco-solvent machines. These ink droplets are measured in pica-litres and a print done at 200dpi will look more defined if it is printed with smaller ink droplets when compared to a machine laying down bigger ink droplets. The primary print head technologies used in ultra-wide format digital outdoor printing comes down to a few print head manufacturers worldwide including (but not restricted to) Piezo, Seiko and Spectra as the primary competitors and their print heads are used in most machines from a variety of manufacturers. They have their pros and cons and Piezo appears to focus more on the higher resolution side of the industry whereas Seiko and Spectra-Polaris tend more towards the robust, high production capabilities required in a manufacturing environment.
   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.
   Monitors do not have dots, but do have pixels; the closely related concept for monitors and images is pixels per inch or PPI. Many resources, including the Android developer guide, use the terms DPI and PPI interchangeably.
  
  Section::::DPI measurement in printing.
  
  DPI is used to describe the resolution number of dots per inch in a digital print and the printing resolution of a hard copy print dot gain, which is the increase in the size of the halftone dots during printing. This is caused by the spreading of ink on the surface of the media.
   Modern computer-monitors typically display about 72 to 130 pixels per inch (PPI), and some modern consumer printers can resolve 2400 dots per inch (DPI) or more; determining the most appropriate image resolution for a given printer-resolution can pose difficulties, since printed output may have a greater level of detail than a viewer can discern on a monitor. Typically, a resolution of 150 to 300 pixel per inch works well for 4-color process (CMYK) printing.
   BULLET::::- 30 mm² area 1/2.3" original Pentax Q (5.6 crop factor). "Current Q-series cameras have a crop factor of 4.55."
   "Effective resolution" is the true resolution of a scanner, and is determined by using a resolution test chart. The effective resolution of most all consumer flatbed scanners is considerably lower than the manufactures' given optical resolution. Example is the Epson V750 Pro with an optical resolution given by manufacturer as being 4800dpi and 6400dpi (dual lens), but tested "According to this we get a resolution of only about 2300 dpi - that's just 40% of the claimed resolution!" Dynamic range is claimed to be 4.0 Dmax, but "Regarding the density range of the Epson Perfection V750 Pro, which is indicated as 4.0, one must say that here it doesn't reach the high-quality [of] film scanners either."
   BULLET::::- It would seem to the software that formula_3 more pixels were available for rendering an image, thereby allowing for bitmap fonts to be created with greater detail.
   BULLET::::- 2002 the DSX telecine HD and Data was shown.
  
  BULLET::::- 2002 Cintel acquired Innovation TK, including the Millennium HD and Data Telecine.
  
  BULLET::::- 2003 Cintel launches GRACE, an internal Film Grain Reducer option for C-Reality and DSX machines
  
  BULLET::::- Millennium II
  
  BULLET::::- 2004 they shown the dataMill fast data scanner based on Millennium 2 technology
  
  BULLET::::- 2004 the GRACE system was shown as an external film grain reducer
  
  BULLET::::- Millennium HD
  
  BULLET::::- ImageMill 1 (video)
  
  BULLET::::- 2005 diTTo - was shown as a low end 2K data scanner, with a 3K native sensor
  
  BULLET::::- diTTo Evolution
   Screen frequency is determined by the type of paper the image is printed on. An absorbent paper surface, uncoated recycled paper for instance, lets ink droplets spread (dot gain)—so requires a more open printing screen. Input resolution can therefore be reduced to minimize file size without loss in quality, as long as the quality factor of 2 is maintained. This is easily determined by doubling the line frequency. For example, printing on an uncoated paper stock often limits printing screen frequency to no more than 120 lpi, therefore, a quality factor of 2 is achieved with images of 240 ppi.
  
  Section::::Computer displays.
   Typical consumer-level flatbed scanners are capable of optical resolution ranging from 100 to 2400 SPI; high-end scanners may have an optical resolution of 4800 SPI or more. Many scanners use interpolation techniques to achieve a higher effective SPI rating, with some manufacturers offering nearly one million SPI, though the quality is primarily limited by the optical resolution; interpolated SPI does not provide additional pixels in the scanned image.
   Dots per inch
  
  Dots per inch (DPI, or dpi) is a measure of spatial printing, video or image scanner dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch (2.54 cm). Similarly, the more newly introduced dots per centimeter (d/cm or dpcm) refers to the number of individual dots that can be placed within a line of 1 centimeter (≈ 0.393 in).
   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 . An inkjet printer sprays ink through tiny nozzles, and is typically capable of 300–720 DPI. A laser printer applies toner through a controlled electrostatic charge, and may be in the range of 600 to 2,400 DPI.
   Another qualifying parameter for a scanner is its "resolution", measured in pixels per inch (ppi), sometimes more accurately referred to as Samples per inch (spi). Instead of using the scanner's true optical resolution, the only meaningful parameter, manufacturers like to refer to the "interpolated resolution", which is much higher thanks to software interpolation. , a high-end flatbed scanner can scan up to 5400 ppi and drum scanners have an optical resolution of between 3,000 and 24,000 ppi.
   BULLET::::- Image Sensor Cleaning function by vibrations and Airflow Control System
  
  BULLET::::- Image area Pixels is the DX Format which can be adjusted to (Large) 6,016 × 4,000 (Medium) 4,512 × 3,000 (Small) 3,008 × 2,000
  
  BULLET::::- Storage media is either SD, SDHC or SDXC, UHS-I bus mode, and Eye-Fi Wireless LAN
  
  BULLET::::- GPS interface for direct geotagging supported by Nikon GP-1
  
  Section::::Features.:Wide dynamic range versus automatic exposure bracketing.
   Pixels per inch (or pixels per centimetre) can also describe the resolution, in pixels, of an image file. A 100×100 pixel image printed in a 1 inch square has a resolution of 100 pixels per inch. Used this way, the measurement is meaningful when printing an image. It has become commonplace to refer to PPI as DPI, even though PPI refers to input resolution. Industry standard, good quality photographs usually require 300 pixels per inch, at 100% size, when printed onto coated paper stock, using a printing screen of 150 lines per inch (lpi). This delivers a quality factor of 2, which is optimum. The lowest acceptable quality factor is considered 1.5, which equates to printing a 225 ppi image using a 150 lpi screen onto coated paper. 
   In 2013, the GNOME desktop environment began efforts to bring resolution independence ("hi-DPI" support) for various parts of the graphics stack. Developer Alexander Larsson initially wrote about changes required in GTK+, Cairo, Wayland and the GNOME themes. At the end of the BoF sessions at GUADEC 2013, GTK+ developer Matthias Clasen mentioned that hi-DPI support would be "pretty complete" in GTK 3.10 once work on Cairo would be completed. As of January 2014, hi-DPI support for Clutter and GNOME Shell is ongoing work.
  
  Section::::Implementation.:Other.
   Where :
  
  "vSPI" is the vertical SPI
  
  "hSPI" is the horizontal SPI (can be considered the same as vSPI if not specified specifically)
  
  "area" is the squared area of the scanned document in inches²
  
  "color depth encoding" is the number of bits used to encode a given amount of color information (256 colors=8; 65'536 colors=16; 16million colors=24)
  
  Remember that this will give raw data bytes, images are almost always compressed when saved to disk using lossless (like PNG, TIFF) or lossy image formats (like JPEG).
  
  Section::::See also.
  
  BULLET::::- dots per inch
  
  BULLET::::- pixels per inch
  
  BULLET::::- lines per inch
   BULLET::::- Resolution, 600 or 1200 dpi (dots per inch) is common in most modern page printers, often with resolution enhancement or anti-aliasing to smooth uneven lines. Higher resolutions are common. Before about 1992, the year Hewlett-Packard made the LaserJet 4, built around a Canon engine, most page printers had only 300 dpi, which made visible jagged lines and relatively poor image quality.
   Some older versions of dvips with embedded bitmapped fonts, which represented letters and symbols as pictures at a fixed resolution (for instance, at 300 dpi). When such files are printed on newer devices (some with resolution of 1200 dpi), the letters of the files that have bitmapped fonts display a remarkably low quality, with jagged lines on curves and diagonals. One solution to this problem is to substitute the bitmapped fonts with scalable fonts (known among PostScript users as Type 1 fonts).
   This must be taken into account when working out the PPI. Using the above calculations requires the screen's dimensions, but other methods require the total pixels, not total dots. 'Dots' and 'pixels' are often confused in reviews and specs when viewing information about digital cameras specifically.
  
  Section::::Scanners and cameras.
  
  "PPI" or "pixel density" may also describe image scanner resolution. In this context, PPI is synonymous with samples per inch. In digital photography, pixel density is the number of pixels divided by the area of the sensor. A typical DSLR, circa 2013, has 1–6.2 MP/cm; a typical compact has 20–70 MP/cm.
  
raw_presuppositions: 300 dpi is the standard resolution for printing.
raw_corrections: 300 dpi is a good resolution for text and line art, but professional printers use 2540 dpi for photo quality prints.