<P> Computers can use pixels to display an image, often an abstract image that represents a GUI . The resolution of this image is called the display resolution and is determined by the video card of the computer . LCD monitors also use pixels to display an image, and have a native resolution . Each pixel is made up of triads, with the number of these triads determining the native resolution . On some CRT monitors, the beam sweep rate may be fixed, resulting in a fixed native resolution . Most CRT monitors do not have a fixed beam sweep rate, meaning they do not have a native resolution at all - instead they have a set of resolutions that are equally well supported . To produce the sharpest images possible on an LCD, the user must ensure the display resolution of the computer matches the native resolution of the monitor . </P> <P> The pixel scale used in astronomy is the angular distance between two objects on the sky that fall one pixel apart on the detector (CCD or infrared chip). The scale s measured in radians is the ratio of the pixel spacing p and focal length f of the preceding optics, s = p / f . (The focal length is the product of the focal ratio by the diameter of the associated lens or mirror .) Because p is usually expressed in units of arcseconds per pixel, because 1 radian equals 180 / π * 3600 ≈ 206,265 arcseconds, and because diameters are often given in millimeters and pixel sizes in micrometers which yields another factor of 1,000, the formula is often quoted as s = 206p / f . </P> <P> The number of distinct colors that can be represented by a pixel depends on the number of bits per pixel (bpp). A 1 bpp image uses 1 - bit for each pixel, so each pixel can be either on or off . Each additional bit doubles the number of colors available, so a 2 bpp image can have 4 colors, and a 3 bpp image can have 8 colors: </P> <Ul> <Li> 1 bpp, 2 = 2 colors (monochrome) </Li> <Li> 2 bpp, 2 = 4 colors </Li> <Li> 3 bpp, 2 = 8 colors </Li> </Ul>

The number of bits of data describing each pixel in a display is referred to as ____