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A monochrome image actually has two colors, the one in the image and the one in the background.
   technofile
Al Fasoldt's reviews and commentaries, continuously available online since 1983

What the jargon of image scanners really means


Oct. 22, 2000

By Al Fasoldt
Copyright ©2000, Al Fasoldt
Copyright ©2000, The Syracuse Newspapers

   Here's what all that jargon means when you're dealing with scanners and images:
   COLOR DEPTH: How many colors are "captured" in the scan. "Depth" is jargon for "bit depth," which indicates how image information is stored. (The more bits, the more colors can be shown.)
   RESOLUTION: A measure of how much detail can be "resolved" in a scan. It's measured in points (or dots) horizontally and vertically that can be detected in each inch of an image. This is called dots per inch or dpi.
   PIXEL: The smallest point, or dot, in an image on the screen. It stands for "picture element," with the "X" added for cuteness.
   LOSSY: Unable to maintain picture quality when an image is saved.
   LOSSLESS: Able to keep the full quality of an image when it is saved.
   JPEG: The most common way of storing the information that makes up an image, pronounced "jaypayg." It's also spelled JPG. (The term stands for Joint Photographic Experts Group, an international association). JPEG images are lossy (see above).
   BMP: An image in which the file that contains the image is a "bitmap" (an exact representation) of all the pixels that make up the image. The most common bitmap file format is the Windows BMP. It is a lossless storage method.
   GIF: An image storage format that uses lossless compression. GIFs normally can't show a lot of colors, which means they're not suitable for scanning photographs.
   TIFF: An image format widely used by professionals. It can be lossy or lossless. Don't use the TIFF format unless you know beforehand that all your software can deal with TIFF images. It's also spelled TIF. The term stands for Tagged Image File Format.
   TRUE COLOR: Able to depict all possible colors. A True Color display uses a color depth of 24 or 32 bits. If you have an Apple Macintosh computer, True Color is called "millions of colors."
   MONOCHROME: Literally, one color. But a monochrome image actually has two colors, the one in the image and the one in the background. So a monochrome image that seems to be black and white is really just black; the white part is supplied by the background on the screen or on the printed page.