Scanner

Scanner Introduction: Scanner is an input device. It reads the graphical images or line art or text from the source and converts it into digital information and send it to the computer.

Scanner

Cont., It reads the graphical images or line art or text from the source and converts it into digital information and send it to the computer. Scanners are used to give large volume of data as input to the computer.

Types of scanner Flat bed scanners Sheet fed scanners Hand held scanners

Flat bed scanners Sheet fed scanners Hand held scanners

Operation Scanner is operates on the principle of reflection. That is, when a light source falls on an image document, the incident light reflects. The reflection depends upon the color and size of the images in the document.

Structure of Scanner That is black or white spaces reflect more light than colored or inked letters or images.

Cont., The light from the lamp is made to fall on the document through the glass plate. The head receives the reflected light from the document with the help of mirrors (m). The reflected light is filtered with the help of R,G,B filters.

Cont., The filtered light is made to fall on a light sensor having 1024 elements using a mirror and a lens. The sensor converts the analog signals into digital signals and is given as output. The scan head is moved over the document with the help of a motor.

Cont., The scan head is move a fraction of an inch at a time. The minimum size of a document that can be scanned depends up on the size of the window.

Scan Resolution The number of dots or pixels per inch a scanner can resoluve for a document. In other words resolution relates to the fineness or clarity of the image scanned by the scanner.

Different Resolutions 200 dpi – Dots Per Inch 400 dpi 600 dpi and so on. The more dots per inch a scanner can resolve, the more clarity the resulting image will have.

Scan modes Line art Half toning Gray scale True color

Line art This mode scans the image and store it as a binary information I0 ‘s and 1 ‘ s). In this 1 represent black color and 0 represent white color. This mode is useful to scan text or line drawings. Picture do not scan well in this mode. This is used to scan black and white images.

Half toning This mode scans the image is such a way that it can be printed by a printer that will not support color printing.

Gray scale This mode scans the image and store it as a 256 gray level information. This is used to scan black and white images.

True color This mode scans the image and store it as color components RED GREEN BLUE This mode is well suited for large and complex images. In this scanning each point is represented by 24 bit- 8 bit for Red, 8 bit for Green, 8 bit for Blue.

File Formats The scanned image can be stored in different file formats. Bitmap File Format - BMP Tagged Image File Format - TIFF CompuServe's Graphics Interchange Format – gif JPEG - Joint Photographic Experts Group

Bitmap File Format Using this format we can store full color images without compression the size of bmp file is large.

Tagged Image File Format Using this format we can store color image with LZW compression. This format reduces the file size without any loss of quality.

CompuServe's Graphics Interchange Format Using this format we can store images using indexed color

Joint Photographic Experts Group Using this format we can store images in a lossly compressed manner. This reduces the file size. Color depth is 24 bits.

Color Scanner

Color Scanner A color scanner is a device capable of capturing images in color. After capturing it converts then into digital images that can be read by computer for display and storage.

The End ….. Thank you …..