question: Why does printer ink use magenta and cyan instead of red and blue?
comment: Cyan, Magenta and Yellow are the negative colour bases. When you mix ink, you will get the negative sum of both colours (mixing all colours perfectly will result in black) because more light colours are absorbed. Red, Green and Blue are the positive colour bases and need to be used when the positive sum is needed, like when mixing light (mixing all will result in white) These are anticolour pairs. When you invert colours Red will turn Cyan, Green will turn Magenta (you have propably seen an inverted colour picture)
passages: BULLET::::- Text is typically printed in black and includes fine detail (such as serifs), so to reproduce text or other finely detailed outlines, without slight blurring, using three inks would require impractically accurate registration.
  
  BULLET::::- A combination of 100% cyan, magenta, and yellow inks soaks the paper with ink, making it slower to dry, causing bleeding, or (especially on cheap paper such as newsprint) weakening the paper so much that it tears.
   By using light cyan or magenta, the printer can saturate areas that would typically use halftoning with these inks to remove the look of sparse magenta and cyan dots. The downside is the printer needs approximately twice as much light cyan and magenta ink in areas to achieve the same saturation as pure cyan/magenta which can lead to excess ink usage. The end result, however, is significantly better for some photos.
  
  CcMmYK colorants reduce graininess in the middle tone region. This reduced graininess typically improves the photographic appearance of blue skies and some flesh tones.
   BULLET::::- Printing typically uses the CMYK color space (cyan, magenta, yellow, and black). Very few printing processes do not include black; however, those processes (with the exception of dye-sublimation printers) are poor at representing low saturation, low intensity colors. Efforts have been made to expand the gamut of the printing process by adding inks of non-primary colors; these are typically orange and green (see Hexachrome) or light cyan and light magenta (see CcMmYK color model). Spot color inks of a very specific color are also sometimes used.
  
  BULLET::::- A monochrome display's color gamut is a one-dimensional curve in color space.
   In inkjet color printing and typical mass production photomechanical printing processes, a black ink K (Key) component is included, resulting in the CMYK color model. The black ink serves to cover unwanted tints in dark areas of the printed image, which result from the imperfect transparency of commercially practical CMY inks; to improve image sharpness, which tends to be degraded by imperfect registration of the three color elements; and to reduce or eliminate consumption of the more expensive color inks where only black or gray is required.
   BULLET::::- Although a combination of 100% cyan, magenta, and yellow inks should, in theory, completely absorb the entire visible spectrum of light and produce a perfect black, practical inks fall short of their ideal characteristics and the result is actually a dark muddy color that does not quite appear black. Adding black ink absorbs more light and yields much better blacks.
  
  BULLET::::- Using black ink is less expensive than using the corresponding amounts of colored inks.
   For some inkjet printers, monochrome ink sets are available either from the printer manufacturer or from third-party suppliers. These allow the inkjet printer to compete with the silver-based photographic papers traditionally used in black-and-white photography, and provide the same range of tones: neutral, "warm" or "cold". When switching between full-color and monochrome ink sets, it is necessary to flush out the old ink from the print head with a cleaning cartridge. Special software or at least a modified device driver are usually required, to deal with the different color mapping.
   While the magenta used in printing and the web color have the same name, they have important differences. Process magenta (the color used for magenta printing ink—also called printer's or pigment magenta) is much less vivid than the color magenta achievable on a computer screen. CMYK printing technology cannot accurately reproduce on paper the color on the computer screen. When the web color magenta is reproduced on paper, it is called fuchsia and it is physically impossible for it to appear on paper as vivid as on a computer screen.
   An emerging method of full-color printing is six-color process printing (for example, Pantone's Hexachrome system) which adds orange and green to the traditional CMYK inks for a larger and more vibrant gamut, or color range. However, such alternate color systems still rely on color separation, halftoning and lithography to produce printed images.
   Magenta
  
  Magenta () is a color that is variously defined as purplish-red, reddish-purple or mauvish-crimson. On color wheels of the RGB (additive) and CMY (subtractive) color models, it is located midway between red and blue. It is one of the four colors of ink used in color printing by an inkjet printer, along with yellow, black, and cyan, to make all the other colors. The tone of magenta used in printing is called "printer's magenta".
   CMYK are the process printers which often have a relatively small color gamut. Processes such as Pantone's proprietary six-color (CMYKOG) Hexachrome considerably expand the gamut. Light, saturated colors often cannot be created with CMYK, and light colors in general may make visible the halftone pattern. Using a CcMmYK process, with the addition of light cyan and magenta inks to CMYK, can solve these problems, and such a process is used by many inkjet printers, including desktop models.
  
  Section::::Comparison with RGB displays.
   In color printing, the color called process magenta, pigment magenta, or printer's magenta is one of the three primary pigment colors which, along with yellow and cyan, constitute the three subtractive primary colors of pigment. (The secondary colors of pigment are blue, green, and red.) As such, the hue magenta is the complement of green: magenta pigments absorb green light; thus magenta and green are opposite colors.
  
  The CMYK printing process was invented in the 1890s, when newspapers began to publish color comic strips.
   In color printing, the color called process magenta or pigment magenta is one of the three primary pigment colors which, along with yellow and cyan, constitute the three subtractive primary colors of pigment. (The secondary colors of pigment are blue, green, and red.) As such, the CMYK printing process was invented in the 1890s, when newspapers began to publish color comic strips.
   BULLET::::- the phosphors or another system actually producing a light that falls inside the red spectrum;
  
  BULLET::::- the overall brightness of the color resulting in the desired color perception: an extremely bright light source will always be seen as white, irrespective of spectral composition.
  
  Hence every output device will have its unique color signature, displaying a certain color according to manufacturing tolerances and material deterioration through use and age.
  
  If the output device is a printer, additional distorting factors are the qualities of a particular batch of paper and ink.
   With the advent of teletext, research was done into which primary and secondary light colors and combinations worked best for this new medium. Cyan or yellow on black was typically found to be optimal from a palette of black, red, green, yellow, blue, magenta, cyan and white.
  
  The opposite color scheme, dark-on-light color scheme, was originally introduced in WYSIWYG word processors, to simulate ink on paper. 
   In 2006, Cone introduced a new concept in ink formulation by developing an ink set for Epson printers that was "color-managed" during formulation by matching the color gamut produced by the OEM's printer driver, rather than attempting to imitate single ink positions that would later be controlled by ICC profiles. ConeColor inks are compatible with Epson Ultrachrome ink sets, being designed for use with the OEM driver, OEM workflow and OEM ICC profiles.
   Split-fount Inking
  
  Split-fount inking also known as Split-fountain inking is a printing technique which allows for subtle gradations of multiple colors without the use of more complex and costly methods such as color separation.
  
  In order to achieve these effects, an ink tray normally intended to receive a single color of ink is instead carefully loaded with two or more separate colors, which then bleed together when applied to the rollers, dynamically creating continuous ranges of hue transitioning from one to the other of the originally applied colors.
   While there are many techniques for reproducing images in color, specific graphic processes and industrial equipment are used for mass reproduction of color images on paper. In this sense, "color printing" involves reproduction techniques suited for printing presses capable of thousands or millions of impressions for publishing newspapers and magazines, brochures, cards, posters and similar mass-market items. In this type of industrial or commercial printing, the technique used to print full-color images, such as color photographs, is referred to as four-color-process or merely process printing. Four inks are used: three secondary colors plus black. These ink colors are cyan, magenta, yellow and key (black); abbreviated as CMYK. Cyan can be thought of as minus-red, magenta as minus-green, and yellow as minus-blue. These inks are semi-transparent or translucent. Where two such inks overlap on the paper due to sequential printing impressions, a primary color is perceived. For example, yellow (minus-blue) overprinted by magenta (minus green) yields red. Where all three inks may overlap, almost all incident light is absorbed or subtracted, yielding near black, but in practical terms it is better and cheaper to use a separate black ink instead of combining three colored inks. The secondary or subtractive colors cyan, magenta and yellow may be considered "primary" by printers and watercolorists (whose basic inks and paints are transparent).
   Before "printer's magenta" was invented in the 1890s for CMYK printing, and "electric magenta" was invented in the 1980s for computer displays, these two artificially engineered colors were preceded by the color displayed at right, which is the color originally called "magenta" made from coal tar dyes in the year 1859.
  
  Besides being called original magenta, magenta dye color is also called rich magenta to distinguish it from the colors "printer's magenta" and "electric magenta", shown below.
   The most noticeable result of using light cyan and light magenta inks is the removal of a distinct and harsh halftoning dot appearance that appears in prints that use light shades of cyan or magenta on the pure CMYK ink configuration. Usually when printing a dark color the printer will saturate the area with colored ink dots, but will use fewer ink dots to create the effect of a light color. The result is hard to notice with yellow because yellow is perceived as a very light color. However, the individual cyan and magenta ink dots will stand out in a sparse pattern due to their darker color against a white background; the result is undesirable when it is noticed.
   To improve print quality and reduce moiré patterns, the screen for each color is set at a different angle. While the angles depend on how many colors are used and the preference of the press operator, typical CMYK process printing uses any of the following screen angles:
  
  Section::::Benefits of using black ink.
  
  The "black" generated by mixing commercially practical cyan, magenta, and yellow inks is unsatisfactory, so four-color printing uses black ink in addition to the subtractive primaries. Common reasons for using black ink include:
   The CMYK model works by partially or entirely masking colors on a lighter, usually white, background. The ink reduces the light that would otherwise be reflected. Such a model is called "subtractive" because inks "subtract" the colors red, green and blue from white light. White light minus red leaves cyan, white light minus green leaves magenta, and white light minus blue leaves yellow.
   Similar to monitors, the inks used in printing produce a color gamut that is "only a subset of the visible spectrum" although both color modes have their own specific ranges. As a result of this, items which are displayed on a computer monitor may not completely match the look of items which are printed if opposite color modes are being combined in both mediums. When designing items to be printed, designers view the colors which they are choosing on an RGB color mode (their computer screen), and it is often difficult to visualize the way in which the color will turn out post-printing because of this.
   Process magenta is not an RGB color, and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color that is pure magenta ink. A typical formulation of "process magenta" is shown in the color box at right. The source of the color shown at right is the color magenta that is shown in the diagram located at the bottom of the following website offering tintbooks for CMYK printing: .
  
  Section::::Three major historical variations of magenta.:Web colors magenta and fuchsia (1990s).
   Process magenta is not an RGB color, and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there may be variations in the printed color that is pure magenta ink. A typical formulation of "process magenta" is shown in the color box at right.
  
  Section::::History.:Web colors magenta and fuchsia.
  
  At right is the web color magenta. It is one of the three secondary colors in the RGB color model.
  
  On the , magenta is the color between rose and violet, and halfway between red and blue.
   With CMYK printing, "halftoning" (also called "screening") allows for less than full saturation of the primary colors; tiny dots of each primary color are printed in a pattern small enough that humans perceive a solid color. Magenta printed with a 20% halftone, for example, produces a pink color, because the eye perceives the tiny magenta dots on the large white paper as lighter and less saturated than the color of pure magenta ink.
  
raw_presuppositions: Primary colors like red and blue would be more suitable than magnets and cyan used as printer ink colors. Primary colors like red and blue would be suitable for printer ink
raw_corrections: Primary colors do not produce black ink when combined like their negative color base counterparts do. Primary colors do not produce black ink when combined like their negative color base counterparts do.