Difference between revisions of "Glossary"

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*'''{{term|chromaticity diagram}}''' - a horseshoe-shaped graph of the Yxy color space where the Y component has been removed and the x and y components are then graphed in 2 dimensions. [[#1|[1]]] <br>See also: [http://en.wikipedia.org/wiki/Chromaticity_diagram Wikipedia]
 
*'''{{term|chromaticity diagram}}''' - a horseshoe-shaped graph of the Yxy color space where the Y component has been removed and the x and y components are then graphed in 2 dimensions. [[#1|[1]]] <br>See also: [http://en.wikipedia.org/wiki/Chromaticity_diagram Wikipedia]
  
Color model
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*'''{{term|color model}}''' - a mathematical model to describe colors and handle them mathematically, such as points in a coordinate system. This is the more theoretically abstract background of color computation. Practically this term is often used synonymously to [[#color space|color space]]. Examples are CIELAB, XYZ and RGB.
A mathematical way of predicting the behavior of human vision or color devices (see Color Space) [1]
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*'''{{term|color space}}''' - a geometric representation of color in space, usually of 3 dimensions [[#4|[4]]]. While color models are the theoretical background color spaces describe the set of visible or reproducable colors [[#2|[2]]]. Practically this term is often used synonymously to [[#color model|color model]]. To get a visual notion of various color spaces and their relationships see [http://www.brucelindbloom.com/WorkingSpaceInfo.html#Viewer Bruce Lindblooms 3D Gamut Viewer] demo. Examples are AdobeRGB, sRGB and Wide Gamut RGB.
  
 
{{right|[[#Table of Contents|Table of Contents]]}}
 
{{right|[[#Table of Contents|Table of Contents]]}}

Revision as of 14:13, 5 January 2014

This glossary holds definitions important for the GIMP development. These include functional definitions i.e. from computer graphics and color theory, photography, terms from BABL and GEGL etc.

Table of Contents

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

References


A

  • 'A (uppercase)' -
    • The alpha channel in a color model, for instance in RGBA.
    • In babl the alpha value in a color model. If combined with alpha-premultiplied color channels: the alpha value each color channel R, G, B was multiplied with to achieve Ra, Ga, Ba. Needed to get from RaGaBa back to RGB. The same applies to R'aG'aB'aA, YaA, Y'aA.
  • 'a (lowercase)' -
    • The axis in the CIELAB color space which denotes the magenta-green component of the image. One end of the axis is green and the other end magenta.
    • In babl: marks a color channel to be premultiplied with alpha , for instance RaGaBa is premultiplied alpha RGB
  • 'Alpha' - opacity. An alpha value of 0 means 'transparent', an alpha value of 100 means 'fully opaque', values in between mean 'partly opaque'.

B

  • 'B (uppercase)' -
    • Blue color channel in the XYZ and RGB color models.
    • brightness component of the HSB color model.
    • In photography: symbol for brightness: obsolete, but may be found on older light meters. [2]
    • Bulb (in photography): Used for long exposures timed by the photographer. Setting for shutter at which shutter opens when shutter button is pressed and stays open as long as shutter button is kept down. [2]
  • 'b (lowercase)' - the axis in the CIELAB color space which denotes the blue-yellow component of the image. One end of the axis is blue and the other end yellow. [1]
  • 'babl' - a dynamic, any to any, pixel format translation library.
    See also: babl website
  • 'brightness' - attribute of a visual perception according to which an area or color appears to emit, or reflect, more or less light. This correlates directly with the amplitude of the lightwave. [1] [4] Translation glossary

C

  • 'C (uppercase)' -
    • Cyan color component of the CMY and CMYK color model.
    • chroma component of the LCH color space.
    • the programming language most of GIMP is programmed in.
  • 'CIE' - Commission Internationale de l´Eclairage (International Commission on Illumination). Independent, non-profit organization for recommendations on photometry and colorimetry. Its aim is to exchange information on all matters relating to the science and art of light and lighting, colour and vision, photobiology and image technology worldwide. It is recognized by ISO as an international standardization body. The CIE has defined several "color spaces" that describe the range of visible colors in unambiguous numerical terms. [1] [4]
  • 'CMY' - Cyan, Magenta, Yellow. The three "subtractive" primary colors used as the basis of all dye or pigment-based printing systems and color photography. A full range of colors including neutral grays and blacks can be produced with good cyan, yellow and magenta colorants (e.g. color film dyes) but typical printing inks are less than perfect. [1]
  • 'CMYK' - Cyan, Magenta, Yellow, Key color (usually Black). The four colors commonly used in process color printing. Black is added to CMY to enhance the density of dark areas and solve gray balance problems encountered when trying to make neutral grays with CMY alone. [1]
  • 'color gamut' - the specific range of colors seen by or reproduced by a device. [1]
  • 'color temperature' - temperature of an ideal black body radiator whose radiation has the same chromaticity as that of a given stimulus. Unit: K (Kelvin). [4]
  • 'chroma' - saturation. It's the colorfulness of an area judged as a proportion of the brightness of a similarly illuminated area that appears white or highly transmitting. The higher the chroma, the more saturated this area appears. [1] [4]
  • 'chromaticity' - The color properties of a sample judged independently of luminance, i.e. in terms of hue and saturation only. [1]
  • 'chromaticity diagram' - a horseshoe-shaped graph of the Yxy color space where the Y component has been removed and the x and y components are then graphed in 2 dimensions. [1]
    See also: Wikipedia
  • 'color model' - a mathematical model to describe colors and handle them mathematically, such as points in a coordinate system. This is the more theoretically abstract background of color computation. Practically this term is often used synonymously to color space. Examples are CIELAB, XYZ and RGB.
  • 'color space' - a geometric representation of color in space, usually of 3 dimensions [4]. While color models are the theoretical background color spaces describe the set of visible or reproducable colors [2]. Practically this term is often used synonymously to color model. To get a visual notion of various color spaces and their relationships see Bruce Lindblooms 3D Gamut Viewer demo. Examples are AdobeRGB, sRGB and Wide Gamut RGB.

D

E

F

G

  • 'GEGL' - Generic Graphics Library, a graph based image processing framework. It is GIMP's foundation for nondestructive image editing in high bit depths. GEGL provides the infrastructure to do demand based, cached, nondestructive image editing on larger than RAM buffers. Through babl it provides support for a wide range of color models and pixel storage formats for input and output. GEGL support in current GIMP versions is experimental and will be official part of GIMP in version 2.10.
    See also: GEGL website, GEGL porting matrix
  • 'GSoC' - Google Summer of Code. Annual mentoring program hosted by Google Inc. to offer and award students to work on open source projects during summer. GIMP has been participating for many years.
    See also: GSoC website, GIMP's GSoC participation

H

I

J

K

  • 'K (uppercase)' -

L

  • 'LGM' - Libre Graphics Meeting. Annual conference of developers and users of graphics open source software. GIMP has been participating for many years. Website
  • 'light, linear' - light as it is in nature and captured by camera sensors (and thus is encoded in RAW images).
  • 'light, percepted' - light as it is processed by eye and brain. The difference between linear and percepted light is that human eyes react to the same change of (linear) light with different sensitivity in dark or light environments. Percepted light is the basis of color (e.g. color is the result of light, processed by eyes and brain).

M

  • 'M (uppercase)' - Magenta color component of the CMY and CMYK color models.

N

O

P

Q

R

S

T

U

V

W

X

Y

  • 'Y (uppercase)' -
    • Yellow color component of the CMY and CMYK color models.
    • In babl: grayscale color model.
    • relative luminance in XYZ color model.
    • luminance in xyY color model.

Z

References

1

CHROMiX ColorWiki

2

idigitalphoto dictionary

3

Wikipedia:HSL and HSV

4

CIE International Lighting Vocabulary