Is a unit of measurement of light wavelength. A nanometer is one million of a millimeter.

A filter that attenuates light evenly over the visible light spectrum. It reduces the light entering a lens, thus forcing the iris to open to its maximum.

Are wavelength from about 400nm down to 250nm. Most photographic emulsions are sensitive to this range of bands.

Type of interpolation in which the value of the new pixel is an average of the neighboring pixels. Quick and dirty interpolation that gives rather ragged results.

A photographic image which tonalities and colours are reversed from the original scene. Usually the film negative is used to make a positive print.

A frame that holds a negative flat in an enlarger.

A series of concentric circles that appear on a scanned image when a thin layer of air exists between the glass scanner bed and the image being scanned. Newton rings appear when light waves are reflected from both top and bottom surfaces of the air between the glass and the image, interfering with the resulting scan.

"Noise can be summarized as the visible effects of an electronic error (or interference) in the final image from a digital camera. Noise is a function of how well the sensor (CCD/CMOS) and digital signal processing systems inside the digital camera are prone to and can cope with or remove these errors (or interference). Visible noise in a digital image is often affected by temperature (high worse, low better) and sensitivity (high worse, low better). Some cameras exhibit almost no noise and some a lot and all the time. It's certainly been the challenge of digital camera developers to reduce noise and produce a "cleaner" image, and indeed some recent digital cameras are improving this situation greatly, allowing for higher and higher ISO's to be used without too much noise. Noise can also affect certain colour channels more than others, this is because a typical digital camera sensor (CCD/CMOS) is more sensitive to certain primary colours than others (often sensors are less sensitive to blue light) and so to compensate, these channels are amplified more than the others. Noise is also often amplified by the JPEG compression algorithm which reacts badly to a very noisy image (often introducing hue errors which weren't in the original noisy image). There are several techniques for cleaning a noisy image, and several products which have been developed to specifically perform this task. Long Exposure "Stuck Pixels" - Another type of noise often referred to as "stuck pixels" or "hot pixels" occurs only with long exposures (1-2 seconds or more) and appear as fixed coloured dots (slightly larger than a single pixel). These stuck pixels can be fairly successfully removed by taking a "dark frame" either before or after the main shot and subtracting this from the original shot, this technique is detailed innoise reduction."

Image compression without loss of quality.