This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (September 2007)

A comparison of the chromaticities enclosed by some color spaces.

A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components (e.g. RGB and CMYK are color models). However, a color model with no associated mapping function to an absolute color space is a more or less arbitrary color system with no connection to any globally understood system of color interpretation.

Adding a certain mapping function between the color model and a certain reference color space results in a definite "footprint" within the reference color space. This "footprint" is known as a gamut, and, in combination with the color model, defines a new color space. For example, Adobe RGB and sRGB are two different absolute color spaces, both based on the RGB model.

In the most generic sense of the definition above, color spaces can be defined without the use of a color model. These spaces, such as Pantone, are in effect a given set of names or numbers which are defined by the existence of a corresponding set of physical color swatches. This article focuses on the mathematical model concept.

Understanding the concept[link]

A comparison of RGB and CMYK color models. This image demonstrates the difference between how colors will look on a computer monitor (RGB) compared to how they will reproduce in a CMYK print process.

A wide range of colors can be created by the primary colors of pigment (cyan (C), magenta (M), yellow (Y), and black (K)). Those colors then define a specific color space. To create a three-dimensional representation of a color space, we can assign the amount of magenta color to the representation's X axis, the amount of cyan to its Y axis, and the amount of yellow to its Z axis. The resulting 3-D space provides a unique position for every possible color that can be created by combining those three pigments.

However, this is not the only possible color space. For instance, when colors are displayed on a computer monitor, they are usually defined in the RGB (red, green and blue) color space. This is another way of making nearly the same colors (limited by the reproduction medium, such as the phosphor (CRT) or filters and backlight (LCD)), and red, green and blue can be considered as the X, Y and Z axes. Another way of making the same colors is to use their Hue (X axis), their Saturation (Y axis), and their brightness Value (Z axis). This is called the HSV color space. Many color spaces can be represented as three-dimensional (X,Y,Z) values in this manner, but some have more, or fewer dimensions, and some, such as Pantone, cannot be represented in this way at all.

Notes[link]

When formally defining a color space, the usual reference standard is the CIELAB or CIEXYZ color spaces, which were specifically designed to encompass all colors the average human can see.

Since "color space" is a more specific term for a certain combination of a color model plus a mapping function, the term "color space" tends to be used to also identify color models, since identifying a color space automatically identifies the associated color model. Informally, the two terms are often used interchangeably, though this is strictly incorrect. For example, although several specific color spaces are based on the RGB model, there is no such thing as the RGB color space.

Since any color space defines colors as a function of the absolute reference frame, color spaces, along with device profiling, allow reproducible representations of color, in both analogue and digital representations.

Conversion[link]

Color space conversion is the translation of the representation of a color from one basis to another. This typically occurs in the context of converting an image that is represented in one color space to another color space, the goal being to make the translated image look as similar as possible to the original.

Density[link]

The RGB color model is implemented in different ways, depending on the capabilities of the system used. By far the most common general-used incarnation as of 2006^[update] is the 24-bit implementation, with 8 bits, or 256 discrete levels of color per channel. Any color space based on such a 24-bit RGB model is thus limited to a range of 256×256×256 ≈ 16.7 million colors. Some implementations use 16 bits per component for 48 bits total, resulting in the same gamut with a larger number of distinct colors. This is especially important when working with wide-gamut color spaces (where most of the more common colors are located relatively close together), or when a large number of digital filtering algorithms are used consecutively. The same principle applies for any color space based on the same color model, but implemented in different bit depths.

Partial list of color spaces[link]

CIE 1931 XYZ color space was one of the first attempts to produce a color space based on measurements of human color perception (earlier efforts were by James Clerk Maxwell, König & Dieterici, and Abney at Imperial College)^[1] and it is the basis for almost all other color spaces. Derivatives of the CIE XYZ space include CIELUV, CIEUVW, and CIELAB.

Generic color models[link]

Additive color mixing: Three overlapping lightbulbs in a vacuum, adding together to create white.

Subtractive color mixing: Three splotches of paint on white paper, subtracting together to turn the paper black.

RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. Light is added together to create form from out of the darkness. RGB stores individual values for red, green and blue. RGBA is RGB with an additional channel, alpha, to indicate transparency.

Common color spaces based on the RGB model include sRGB, Adobe RGB and ProPhoto RGB.

CMYK uses subtractive color mixing used in the printing process, because it describes what kind of inks need to be applied so the light reflected from the substrate and through the inks produces a given color. One starts with a white substrate (canvas, page, etc.), and uses ink to subtract color from white to create an image. CMYK stores ink values for cyan, magenta, yellow and black. There are many CMYK color spaces for different sets of inks, substrates, and press characteristics (which change the dot gain or transfer function for each ink and thus change the appearance).

YIQ was formerly used in NTSC (North America, Japan and elsewhere) television broadcasts for historical reasons. This system stores a luminance value with two chrominance values, corresponding approximately to the amounts of blue and red in the color. It is similar to the YUV scheme used in most video capture systems^[2] and in PAL (Australia, Europe, except France, which uses SECAM) television, except that the YIQ color space is rotated 33° with respect to the YUV color space. The YDbDr scheme used by SECAM television is rotated in another way.

YPbPr is a scaled version of YUV. It is most commonly seen in its digital form, YCbCr, used widely in video and image compression schemes such as MPEG and JPEG.

xvYCC is a new international digital video color space standard published by the IEC (IEC 61966-2-4). It is based on the ITU BT.601 and BT.709 standards but extends the gamut beyond the R/G/B primaries specified in those standards.

HSV (hue, saturation, value), also known as HSB (hue, saturation, brightness) is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSV is a transformation of an RGB colorspace, and its components and colorimetry are relative to the RGB colorspace from which it was derived.

HSL (hue, saturation, lightness/luminance), also known as HLS or HSI (hue, saturation, intensity) is quite similar to HSV, with "lightness" replacing "brightness". The difference is that the brightness of a pure color is equal to the brightness of white, while the lightness of a pure color is equal to the lightness of a medium gray.

Commercial color spaces[link]

• Munsell color system
• Natural Color System (NCS)

Special-purpose color spaces[link]

• The RG Chromaticity space is used in Computer vision applications. It shows the color of light (red, yellow, green etc.), but not its intensity (dark, bright).

Obsolete color spaces[link]

Early color spaces had two components. They largely ignored blue light because the added complexity of a 3-component process provided only a marginal increase in fidelity when compared to the jump from monochrome to 2-component color.

• RG for early Technicolor film
• RGK for early color printing

See also[link]

Wikimedia Commons has media related to: Color spaces

• Color theory
• List of colors

References[link]

1. ^ William David Wright, 50 years of the 1931 CIE Standard Observer. Die Farbe, 29:4/6 (1981).
2. ^ Dean Anderson. "Color Spaces in Frame Grabbers: RGB vs. YUV". http://www.sensoray.com/support/frame_grabber_capture_modes.htm. Retrieved 2008-04-08. 

External links[link]

• Color FAQ, Charles Poynton
• FAQ about color physics, Stephen Westland
• Color Science, Dan Bruton
• Color Spaces, Rolf G. Kuehni (October 2003)
• Colour spaces - perceptual, historical and applicational background, Marko Tkalčič (2003)
• Color formats for image and video processing - Color conversion between RGB, YUV, YCbCr and YPbPr.
• C library of SSE-optimised color format conversions.
• Konica Minolta Sensing: Precise Color Communication

John Paul Caponigro (born June 23, 1965 Boston) is an Environmental Fine Art Landscape Photographer. He is the son of the American photographer Paul Caponigro and Eleanor Caponigro a graphic designer.^[1] John Paul attended Yale University, and the University of California, Santa Cruz where he was trained as a painter and later as a photographer. After college John moved to Maine and became an artist in residence at The Center for Creative Imaging.^[2] John now works with photo-based digital imaging as his primary medium. Dan Steinhardt of Epson considers John Paul "...one of the great mentors of the photographic medium".^[3] The American photographer Joyce Tenneson has said, "John Paul Caponigro is the rare combination of gifted artist and master technician. He works from the heart to create images that are poetic and evocative, and at times, mystical. He is someone whose sensitivity and intelligence work to break new ground, and someone I will enjoy watching in the years to come.".^[4] He has been awarded membership into many photographic organizations including the Photoshop Hall of Fame,^[5] the Epson Stylus Pros,^[6] Xrite Coloratti,^[7] and the Canon Explorers of Light.^[8] His work crosses the lines between photography and painting and displays knowledge of painterly composition and color theory, coupled with content of modern science, psychology, primal cultures, and the environment.^[2] The photographer Arnold Newman stated,"...Caponigro's mysterious and magical images go beyond reality or surrealism. He has created a wonderful new world of his own".^[9] John Paul Caponigro lives in Cushing, Maine with his photographer wife Arduina, and their son.

Exhibits[link]

From 1990 to 2011 John Paul Caponigro has had over 110 group and solo shows.^[10] He has shown internationally in Italy at the Museo Archeologico Regionale, Val d’Aosta,^[11] and the VIR, SpA, Milan. John has shown his work in the United States in galleries and museums such as the Palm Beach Photographic Centre Museum, Delray Beach, FL and the Pingree Gallery in East Hampton, NY, and the Pasadena Museum of California Art, CA. He has a yearly gallery showing of his newest work each August at his gallery/studio in Cushing, ME.^[12]

Collections[link]

John Paul's photographic work is included in corporate and museum collections. These include Estée Lauder and Pfizer, Princeton University and The Museum of Fine Arts Houston. The Smithsonian Museum of American National History has a collection of John Paul's work that includes one of every media that he has used. This collection includes his early silver gelatin prints, his current pigmented ink prints, preliminary sketches and his print-on-demand books. The Smithsonian is also collecting the tools he uses to produce his work, this includes his software, computers, printers, cameras and cell phones.^[13]

John interviewed over 40 of the great American photographers from 1995 through 2007. These dialogs were published in Camera Arts Magazine the audio tapes of which are now archived at the Eastman House Library, Rochester New York. The transcripts of these dialogs can be viewed on John Paul Caponigro's website.

Lectures[link]

John Paul Caponigro lectures at trade-shows, professional organizations, educational institutions, and corporations, including: MIT, Penn State, RIT, Microsoft, Photo Plus, ASMP and Photoshop World. In 2010 John spoke on creativity for TEDx Dirgo.^[14]

Awards[link]

In 2002 Caponigro won the honor of being voted one of Zoom Magazine's 15 Best Artists of Past 30 Years.^[15] In 2003 he was Photo District News' Annual Winner,^[16] and in 2008 he won the Communication Arts Award of Excellence.^[17]

Workshops[link]

Caponigro runs International and American landscape workshops. He has traveled to Antarctica 3 times ^[18] leading photographic workshops. Pieces of his Antarctica work have been shown at the Peabody Essex Museum in Salem Massachusetts in 2008.^[19] He has done workshops in South Africa and Namibia, and works with Focus on Nature in Iceland doing workshops with them since 2008. In 2010 John and fellow Canon Explorer of Light photographer, Seth Resnick, began running international workshops together through Digital Photo Destinations, an international field workshop company which holds workshops in Antarctica, Greenland and Patagonia. His American field destination workshops included desert destinations such as White Sands, New Mexico, Arches National Park in Utah, Death Valley,CA and Santa Fe, New Mexico. John teaches field photography workshops on Maine Islands, and Maine Fall Foliage out of his studio in Cushing, Maine.

Next Step[link]

John runs printing and creativity workshops out of his Maine studio. Known as a master printer ^[20] he offers printing workshops for students who wish to turn their images into fine art prints. The John Paul Caponigro Next Step Alumni Group was formed in 1998 when a handful of students requested custom workshops to increase their photographic creativity.^[21] The Next Step group has grown from this small body of students to just under 100 photographers. Membership into this group is by invitation only, and group dynamics are a factor in nomination. The Next Step group have held exhibitions of their work at the Maine Media Workshop in Rockland, Maine ^[22] and at the Renaissance Gallery in Carmel, Indiana.^[23] They have produced two books on their work.^[24]

Books / Articles/ DVD's[link]

John Paul's art is the subject of published articles and books on photography and creativity. A Camera Arts article by Sean Kernan in 1999, Paul Slaughters 2007 AfterCapture article,^[25] and a 2010 Scott Sheppard Nik Radio interview,^[26] discuss John's creative process. His images have been included in over 20 books on Fine Art Photography.^[27]

John Paul contributes to photographic and news publications. These include - Camera Arts, Digital Photo Pro, Apple,^[28] and The Huffington Post.^[29] In 2000 Adobe Press published his first book "Adobe Master Class". It was followed up with a second printing in 2003.^[30] This book describes techniques and use of digital technology for artistic purposes. He has also self-published catalogs of his work.^[31] John has authored ten DVDs on Photoshop techniques through Acme Educational,^[32] a digital media learning resource.

Reading[link]

John Paul Caponigro started his website Illuminating Creativity in 2005. The educators website includes information on his workshops, seminars, books, DVDs, prints, gallery exhibits, links to environmental groups, a current calendar of lectures and seminars and the artists' curriculum vitae. The website includes downloadable PDF's on creativity, printing and photographic techniques and bookmaking.

References[link]

External links[link]

• www.johnpaulcaponigro.com
• www.digitalphotodestinations.com
• http://jpc.acmeeducational.com/jpc/index.html
• http://www.focusonnature.is/page/John_Paul_Caponigro_Destination_Iceland

Paul Caponigro (born December 7, 1932), is an American photographer.

Photography career[link]

Caponigro was born in Boston, Massachusetts. He studied with Minor White and has been awarded two Guggenheim Fellowships and three grants from the NEA. His best known photograph is Running White Deer. Caponigro's first one-man exhibition took place at the George Eastman House in 1958. In the 1960s Caponigro taught photography part-time at Boston University while consulting the Polaroid Corporation on various technical research.

In 1971, his work was exhibited in group exhibition "Le Groupe Libre Expression : Expo 5", presented by Jean-Claude Gautrand, at Les Rencontres d'Arles festival, France.

Caponigro's work is included in the collections of the Guggenheim, Whitney, Norton Simon Museum, Museum of New Mexico and San Francisco Museum of Modern Art. His son, John Paul Caponigro, is a noted digital photographic artist.

Quotes[link]

• “I often see the materials of photography as being a type of terrain. Emulsions, liquid developers, silver salts, and fixers interact, and I construct a landscape that I need to first explore in my mind’s eye if I am to make it manifest as an artful image in silver.”
• "Photography is a medium, a language, through which I might come to experience directly, live more closely with, the interaction between myself and nature."
• "At the root of creativity is an impulse to understand, to make sense of random and often unrelated details. For me, photography provides an intersection of time, space, light, and emotional stance. One needs to be still enough, observant enough, and aware enough to recognize the life of the materials, to be able to 'hear through the eyes'."

Books[link]

• Veiled Yet Revealed: Masterworks from Fifty Years
• Paul Caponigro: Masterworks of Forty Years
• Paul Caponigro - New England Days
• Paul Caponigro: Of the Earth, Still Life Studies 2001~2004
• Megaliths
• [New England Days ISBN 978-1-56792-216-5]
• [Landscape ISBN 978-0-07-009780-3]
• [The Wise Silence ISBN 978-0-8212-1548-7]
• Sunflowers

External links[link]

• Artcyclopedia, Paul Caponigro
• Amico Public Collection