Calibration. The act of adjusting the color of one device to match that of another. For example when you match the calibration of your screen to that of your printer to ensure what you see is what you print. It is also used in the film SLR's Canon EOS-3 and EOS 5 which have eye-controlled focussing. You calibrate the cameras focussing to where your eye is looking in the viewfinder. (Some fighter planes also have this. The missile follows the trajectory of the pilot's eye).
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Card Reader. Used for transferring data from your flash memory card to your PC. A better way of transferring your image files than connecting the camera to your PC. Sometimes the cameras circuitry can become corrupt. Better to fry a memory card than your camera.
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CCD (Charged Coupled Device). This is a light sensitive chip used in your digital camera for image gathering. The CCD Pixels gather the color from the light and pass it to the shift register for storage. CCD's are analogue sensors, the digitising occurs when the electrons are passed through the A to D converter. This "Analogue to Digital" converter converts the analogue signal to a digital file or signal.
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Centre -Weighted. Term used to describe an automatic exposure system that uses just the centre portion of the image to adjust the overall value. So in effect, the exposure will be weighted to what you see towards the centre of your viewfinder.
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CF. Compact Flash card. Used in your digital camera to record images. Storage space ranges from 16MB up to 12GB. A company in Japan is currently developing a CF card that will store 2TB of information or 2,000 Megabytes.
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Channel. One piece of information stored with an image. For example, a true color image has 3 channels, red, green and blue.
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Chroma. The color of an image element or pixel. A chroma is made up of saturation plus the hue values, but is separate from the luminance value.
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Chromatic Aberration. Also known as purple fringing. It is fairly common in 2MP digital cameras and above, especially if they have long telephoto lenses. You can see it when a dark area is surrounded by a highlight. In between the dark and light, you may see a band of purple pixels that shouldn't be there. There are ways of removing this which I have covered in the Photoshop section.
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CMOS. Complementary Metal Oxide Semiconductor (now you can see why it is abbreviated) - Another imaging system used by digital cameras. These produce lower amounts of power consumption, but are not as popular as the CCD sensors used in most digital SLR's
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CMS. Color management system. A software program designed to ensure color matching and calibration between video and/or computer monitors and any form of hard copy output.
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CMYK. Cyan, Magenta, Yellow and BlacK. Colors used by most printers to produce your prints. Color shifts can be caused when the color management system tries to convert your PC's RGB files to CMYK. Before printing, try converting your images to CMYK and see what the difference is.
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Color Balance. The accuracy with which the colors captured in the image, match the original scene.
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Color Cast. This is a very unwanted tint of one color in an image caused by the wrong amount of Cyan, Magenta and Yellow. It can be corrected using your editing software.
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Color Correction. To correct or enhance the colors within an image.
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Color Depth. Digital Images can approximate color realism but the process is referred to as color depth, bit depth or pixel depth. Most modern computer displays use 24 bit true color. It displays the same number of colors that the human eye can discern, about 16 million.
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Color Space. Digital cameras use known color profiles to generate their images. The most common is sRGB or Adobe RGB. This along with all of the other camera data is stored in the Exif header of the Jpeg file. The color space information ensures that graphic programs and printers have a reference to the color profile that the camera used at the time of taking the exposure.
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Compact Flash. See CF. This is the most commonly used type of memory. It is small, removable and available in a wide range of sizes up to 12GB.
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Compression. A Digital photograph creates an image file that is enormous. To enable image files to become smaller and more manageable cameras employ some form of compression such as JPEG. RAW and TIFF files have no compression and take up more space.
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Continuous Autofocus. As it says. The auto focus system is continuously working on focussing on the subject.
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Contrast. The measure of rate of change of brightness in an image.
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CRW. The RAW CCD file format used by Canon Digital Cameras. Comes from Canon RAW.
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