From GIMP Developer Wiki
Revision as of 22:34, 3 January 2014 by Scl
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 (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 (uppercase) -
- Blue color channel in the XYZ and RGB color models.
- Brightness component of the HSB color model.
- In photography: symbol for luminance (e.g. brightness): obsolete, but may be found on older light meters. 
- 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. 
- 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. 
- babl - a dynamic, any to any, pixel format translation library. (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 light waveform.   Translation glossary
- C (uppercase) - Chroma component of the LCH color space.
- 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.  
- color temperature - temperature of an ideal black body radiator whose radiation has the same chromaticity as that of a given stimulus. Unit: K (Kelvin). 
- chroma - 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.  
- chromaticity - The color properties of a sample judged independently of luminance, i.e. in terms of hue and saturation only. 
- K (uppercase) - Kelvin. Unit of color temperature.
- Mired - former, obsolete unit of reciprocal color temperature.