Thursday, January 18, 2007
Digital Camera Fundamentals
A useful glossary to help you decode some of digital's terminology
LD, ED and UD Glass (Low-Dispersion, Extra-Low-Dispersion and Ultra-Low-Dispersion Glass) All these terms refer to a glass type used in lenses. They denote rare or specially formulated glass that corrects the path of light rays as they pass through the lens, making all colors in the color spectrum focus at the same point.
Megapixel (one million pixels) The number of photodiodes (also known as photosites or pixels) on an image sensor is expressed in megapixels, which in turn is the resolution of the device (a camera, scanner, etc.). Most sensors have one photodiode for each pixel in an image. For example, a 5-megapixel camera has five million photodiodes.
Noise Image artifacts caused by statistical variations with color that manifest themselves as grain on an image. Excessive noise usually results in an objectionable-looking image. Smaller image sensors with physically smaller photodiodes are more subject to noise than sensors with larger photodiodes.
RAW An image-capture option containing the maximum information available from a sensor. The format is offered by many high-end compact digital cameras as well as D-SLRs. Each camera company has its own RAW format and corresponding software to support the format.
Resolution Camera resolution expressed in the number of photodiodes (megapixels) on the image sensor. More megapixels equals higher resolution. It's important to note that many factors go into image quality, and resolution is only one of them. If you have a poor-quality lens on a high-resolution camera, you'll get a high-resolution image of poor quality. Higher-resolution image files can be enlarged with less interpolation than lower-resolution image files.
TIFF (Tagged Image File Format) A standard image file format for bitmapped graphics. TIFF files are uncompressed and, therefore, very large compared to compressed formats. Because TIFF is a standard, TIFF image files can be read by all image-processing software.
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