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  • A/V outputs
    "Video or A/V outputs are fairly common on digital cameras

  • Aberration
    (1) Something that prevents light from being brought into sharp focus, disenabling the formation of a clear image. (2) Lens flaw - the inability of a lens to reproduce an accurate, focused, sharp image. Aberration in simple lenses is sub-categorized into seven types:
    Astigmatism - lines in some directions are focused less sharply than lines in other directions,
    Chromatic aberration or Axial chromatic aberration - different wavelengths of light coming into focus in front of and behind the film plane, resulting in points of light exhibiting a rainbow-like halo and reduction in sharpness,
    Coma - the image of a point source of light cannot be brought into focus, but has instead a comet shape,
    Curvilinear distortion - distortion consisting of curved lines,
    Field curvature - the image is incorrectly curved,
    Lateral chromatic aberration also known as Transverse chromatic aberration - variation in the magnification at the sides of a lens (this aberration type used to be termed lateral colour),
    Spherical aberration - variation in focal length of a lens from center to edge due to its spherical shape - generally all parts of the image, including its center.?The effects of lens aberration usually increase with increases in aperture or in angle of field.

  • Absolute colorimetric
    A rendering intent that aims to maintain colour accuracy at the expense of preserving relationships between colours, used to predict how images will appear when printed on paper or other substrate with a distinct colour cast, such as newsprint. With absolute colorimetric rendering intent, colours that falls inside the destination gamut remain unchanged, while out-of gamut colours are clipped. Colours are not scaled to the destination white point.

  • Achromatic
    Is a lens system that has been corrected for chromatic aberration.

  • Acutance
    A measure of the sharpness with which the film can produce the edge of an object.

  • AD conversion
    Analog-Digital Conversion. In order to process a continuous analog signal in a computer (e.g. a photo), it must first be digitized, which means, converted into a specific mathematical format of binary code. Pictures are usually digitized with the help of a digital camera or a scanner.

  • Adaptive compression
    A type of compression software commonly used to back up files. The method of compression changes with the type of file, and is not recommended for photographic images because it may destroy original data.

  • Additive colour model
    The color model in which colours are produced by combining various percentages of red, green, and blue light. In the additive colour model, white is produced by mixing 100% of each primary, whereas black is produced the absence (i.e., 0%) of each primary. The additive colour model is used by computer monitors to produce their display.

  • additive primaries
    Red, green, and blue light that produce white light when added together.

  • Additive primary colours
    "Red, Green, Blue

  • Adobe colour engine (ACE)
    The colour management model created by Adobe Systems, Incorporated that is the default conversion engine used for ICC colour-managed colour conversions with Adobe applications.

  • Adobe RGB (1998)
    The RGB working space created by Adobe Systems, incorporated that provides a fairly large gamut of colours and is well-suited for documents that will be converted to CMYK

  • Aliasing
    "When a line or any shape (curve, circle or font text character) is painted, and its edges are not perfectly horizontal or vertical, some pixels are only partially covered. The resulting jagged-edged lines are said to be aliased. Aliasing gives lines a "stair-step" or "jaggie" appearance. The greater the number of dots or pixels on your display, the higher the display resolution, and the less noticeable aliasing is to the human eye."

  • Ambient light
    The natural light in a scene.

  • Analog to digital (A/D) converters
    A device which converts an analog signal into a digital signal. Complex waveforms are converted into simple strings of numbers.

  • Aperture
    The size of the lens opening, which regulates how much light passes through the lens to hit the CCD. Aperture is measured in f-stops. A higher number equals a smaller amount of light. Some digital cameras (such as digital SLR cameras) allow a user to manually adjust the aperture setting.

  • Application
    A computer program, such as an image editor or image browser.

  • Archival
    The ability of a material, including some printing papers and compact discs, to last for many years.

  • Artifact
    Colour faults or line faults that visibly impact the image negatively. Any visible degradation of an image caused by scanning, editing or compressing the image. Often artifacts are regular or repeating, rather than random.

  • ASCII
    (American Standard Code for Infor-mation Interchange) A standard format for representing data or text in 8-bit chunks.

  • Astigmatism
    A lens aberration or defect that is caused by the inability of a single lens to focus oblique rays uniformly. Astigmatism causes an object point to appear as a linear or oval-shaped image.