Optical input devices are those devices that use light as a source of input. The important use of these devices is that they eliminate the need of entering the data manually and accurate result can be obtained. There are three main types of optical input devices:
1- Bar Code Readers
2- Image Scanner
3- Optical Character Recognition
BAR CODE READERS
Bar code readers is one of the most commonly used type of optical input devices. It is also known as price scanner.
Bar code consists of a white background with black lines on it which is found on products like snacks, beverages, industrial products, etc. These lines contain information.
Bar code reader is an electronic device which is used to capture and read information contained in a bar code. It converts that information into code understandable by the computer. It is time saving and faster in speed otherwise the salesman has to compute the price manually which is sometimes not correct and other customers have to wait long.Whenever you go to the supermarket you see that the person on counter uses bar code reader to scan the information and price of the purchased product and it is automatically displayed on the computer. Optical character recognition (OCR) is the recognition of printed or written text characters by a computer. If you have scanned a text document you might want to use optical character recognition software to translate the image into text that you can edit. This process involves the scanning of letters word by word, analysis of the scanned images is done and then transmission of the characterized images into character code is made, such as ASSCI, which is commonly used in data processing.
BITMAP:
A bitmap is a grid of dots, each drop represented by one more bits. Bitmap comes from a computer terminology meaning “a map of bits”. The format of bitmap is used to store digital images.
FUNCTION OF OCR:
The job of OCR is to translate that array of dots into text that the computer can interpret as letters and numbers. In OCR processing, the scanned image identifies each and every letter or numeric value. When it recognizes a character it converts it into an ASCCI code. Especially designed circuit boards and computer chips for OCR are used to speed up the recognition process. Optical Character Recognition is fully automated process that converts these images, letters or numeric values into such language that is easily readable and understood by the computer software. After this the computer system can search the OCR generated text for words, phrases or other characters.
ADVANTAGE OF OCR:
For many documents as well as input tasks, OCR is the most cost effective and speedy without available each year OCR frees acres of storage space once given over to file cabinet and full of paper cabinet. Before the usage of OCR, the source material must be scanned using an optical scanner to read in the pages as bitmap
OCR is of great use in this present era it not only helped us to reduce our work but also helped us a lot in making of multiple copies in short span of time. Millions of books are being scanned and printed for various purposes rather it’s for recording various documents, educational and professional books, magazines, newspapers and onwards.In the past people used to write the whole book with their own hands but were only able to make only one copy of it. By the passage of time and advancement of technology the expertise were able to make such machines and systems that proved beneficial for us as well as for our work. Suppose we want to write a novel overnight. You could stay up all night typing and still not finished or you could use a high end scanner and in minutes can scan all of authors work into a computer using optical character recognition technology. This is the technology long used by libraries and government agencies to make lengthy documents quickly available to electronically. Advances in OCR technology have made its mark in the world through its enterprise.It is an input device. A scanner is just like a copier but instead of copy on to paper it creates an image file of scanned image. Once the image is in digital form you can easily store it on computer hard disk, add to any poster design, manipulate or use with graphics design program and many more. Scanners are also called image scanners.Once your image is being scanned, it then requires some software to convert digital code to a viewable image.
HOW AN IMAGE IS SCANNED?
A light source is being used across the printed page.
The light then bounces and passed through a lens
Then it passes through a light sensitive diode. Diodes convert light to electricity. There are 300 to 600 diodes per inch.
After it a circuit board is used to convert electricity and then sends the information to the computer for scanning.
TYPES OF SCANNERS
1) FLATBED SCANNERS:
Are the most versatile scanners. They are also called desktop scanners.
2) SHEET-FED-SCANNERS:
It is similar to flatbed scanners but in it document is moved and scan head is immobile. It looks a lot like small portable printers.
3) HANDHELD SCANNERS:
It works on the same technology as a flatbed scanner but it depends on the user to move it instead of a motorized belt. Handheld scanners cannot provide good quality image but it can be useful for quick capturing of text
4) DRUM SCANNERS:
Are used for detailed images by publishing industries. These scanners scan image with photomultiplier (PMT). Drum scanners uses three PMTs red, blue and green for reading.
5) FILM SCANNERS:
Film strips are placed in a carrier inside the film scanner. Thus carrier moves with the help of motor along with lens and a CCD (charged- coupled device) scanner.
6) 3D SCANNERS:
These scanners depend on the placement of marker that it uses to align the element’s position.
7) DESKTOP DIGITAL CAMERA SCANNERS:
This canner is all in one scanner with one printer and desktop digital camera scanner. This scanner has high speed.
8) SMARTPHONE SCANNERS:
It is very common and provides image output in JPEG and documents output in PDF formats. Apps can be downloaded on many smart phones to scan documents and digital camera exposure or images.
OBJECTIVES OF SCANNERS:
To reduce the time we spend on data input.
To capture the pictures, photo graphics or drawings directly in shorter time.
To save and secure the images for future uses.The first image scanner was used in 1957 at US National Bureau of standard by a team headed by RUSSEL A. KIRSCH. He scanned his three month old son’s image which was of 5cm square and black and white image having resolution of 176 pixels on a side.
USES OF IMAGE SCANNERS:
PHOTOSHOP: Editing of pictures which is now become a common practice
OCR: Optical Character Recognition converts graphical image to standard text that can be edited using word processing and text editing software
BIOMEDICAL RESEARCH: It is used as DNA microarrays. These scanners are of very high resolution system up to 1 pixel similar to a microscope.
COMMON SCANNER SOFTWARES IN EARLY STAGES
SANE: (Scanner Access Now Easy) is developed for UNIX and Linux operating systems.
TWAIN: (Technology without Acronyms Is Nothing) is used by most of the scanners. It is widely used for large volume scanning.
ISIS: (Image Scanner Interference Specification) it is used by large and departmental scale machines.
WIA: (Windows Image Acquisition) is used on Microsoft windows provided by Microsoft. It is an API (Application Programming Interface).
Now scanners are plug in play you attest the cable with the system and image is ready for scan.