Achromatic Colour:
Achromatic colour refers to the primary RGB colours of light. These primary colours are utilised by many of the scanners, computer monitor and other computer devices.

Alignment:
Alignment refers to the position of the scanner or the light source with respect to the position of the receiving element.

Anti-aliasing:
It is the process of removing the stepping effect that is found in the diagonal lines of the image. And the process involves insertion of in between tone dots along the edges.

Aperture:
Aperture is an integral part of the optical path in devices such as scanners, camera, etc. Usually they are circular in shape, but rectangular and elliptical apertures are also available.

Aspect Ratio:
Aspect ratio refers to the relative proportion of the dimensions of an image. That is, if you scan an image with original dimensions of 4 by 6 inches, then its aspect ratio is the ratio of its width and height.

Automatic Document Feeder:
It is a device attached to the scanner that automatically feed the documents in to the scanner in one page at a time. And thus enables you to scan multiple pages at a time.

Binary:
Binary refers to the numbering system to base 2. In binary format any number can be represented as a combination of digits 0 and 1. In computing, these are represented electrically by off and on.

Bit:
Bit is an abbreviation of binary digit 0 or 1. Scanners usually use multiple bits to represent the information about the pixels of an image.

Bitmap:
It is an image format in which the information about the image is represented as pixels in a row and column format.

Calibration:
It is a way of correcting the variation between the output when compared to the original image data from the scanner.

Charge Coupled Device:
It is a type of solid state sensor used in most of the modern scanning devices. It captures light that are transmitted or reflected by the original.

CMOS:
CMOS abbreviated as Complementary Metal Oxide Semiconductor Sensor is a latest type of sensor that is used in many of the modern camcorders, scanning devices, etc. It functions based on the digital electronics rather than the traditional analogue electronics.

Colour Correction:
Colour correction is the process of adjusting the colour balance of an image so as to generate more accurate representations of the colours in an image. Colour correction helps in rectifying the undesired colour balance in the original image.

Contact Image Sensor:
This is a type of sensor that has some limitations on its resolution. Hence, used in smaller and low cost scanners.

Contrast:
Contrast refers to the range of lightest and the darkest tones in an image. In a highly contrasted image, the shades of all the colours fall at the extremes of the range (i.e.) between the black and white colours.

Device Driver:
Device driver is software that is used to instruct the operating system about how to control the given hardware.

Dithering:
Dithering is the process of simulating the gray colour tones by grouping the dots. And then the grouped dots can be merged in to intermediate colour tones.

Dots per Inch:
Dots per Inch usually abbreviated as dpi, is used to represent the resolution of the printed page. And it is expressed in the number of dots per inch scanned.

Filter:
It is an image transformation tool that is used to process an image. It performs various processes such as sharpening, blurring, diffusing, etc on the images. Filters can be implemented by using both hardware and software.

Gamma Compensation:
Gamma compensation is the process of adjusting the image so as to correct the gamma of the device that is used to reproduce the image. The image would look more dark if gamma compensation is not done.

Graphics Interchange Format:
It is a compressed image file format that is more popular over the internet. GIF was the most commonly used image file format.

Interpolation:
Interpolation is the process of changing various attributes of an image like size, colours, resolution, etc. It is done by mathematically calculating the pixel values that are used to represent the new image.

Joint Photographic Experts Group:
It is the most commonly used image file format that offers a compression scheme that makes image file size smaller when compared to any other file format. It does so my eliminating some information about the image.

Monochrome:
Monochrome refers to single colour. An it is usually used to refer the black and white images.

Optical Resolution:
Optical resolution refers to the resolution of the scanner. And it is calculated by taking the ratio of width of the scanned area to the number of pixels in the charge Coupled Device.  Optical resolution is usually called as true resolution and it does not include any additional interpolation to increase the pixels.

Pixel:
An image is made up of number of pixels. And it refers to single dot in a digital photograph.

Raster Image:
Raster image is an image that is defined by rows and columns of pixels. Most of the scanners used to capture images in the raster form, and may or may not convert it in to vector form.

Resolution:
Resolution refers to the number of pixels or dots per inch in an image.

Sharpening:
It is process of improving the sharpness of the original image. And it is done by increasing the contrast between the adjacent colour tones.

Threshold:
It is a fixed predefined level used by the scanners to check whether the pixel should be represented as a black or white.

Tagged Image File Format:
It is a graphical image file format that was developed specifically for scanners. And it can be used to store both the gray scale images and the colour images.