How A Computer Scanner Works

Scanners can play a vital role in a home office by allowing a user to take various documents and convert them to images, which can then be used in many applications. There are several types of scanners, such as flatbed scanners, sheet-fed scanners, handheld scanners and drum scanners, with each allowing a user to feed a document into the scanner in different ways. A majority of home offices make use of a flatbed scanner, which may be a separate unit or could be part of multifunction copier (MFC). An MFC can scan a document or picture and produce a copy if necessary. Now let’s look into how a computer scanner works:

Photosites And Diodes

The basic concept behind a scanner is very similar to a digital camera. When a document is placed on or into the scanner, the CCD, or charge-coupled device, harnesses the power of photosites, which are diodes. Digital cameras also contain CCDs. These photosites emit an electric charge when exposed to light. The more light exposed to a photosite, the greater the charge. When a strong light is shined on the document, the information from these tiny diodes are collected in the CCD, which interprets the charges into images that become files. These files are then transferred over to the computer that is connected to the scanner.

The scanner’s main goal is to make sure the CCD runs as smoothly as possible, allowing it to completely capture the details of a document without interference. A scanner is not “reading” a document, it is simply interpreting the information from the diodes, which can be a slow process. Software tracks the timing and position of the CCD to understand what part of the document is being scanned.

File Conversion

Once the document is converted into a file, the user can manipulate that file as he or she wishes. A computer can use OCR (optical character recognition) software to extract text from a scanned image. The quality of the text extracted is dependent on the quality of the scan. High-end scanners can produce near exact copies of a document under optimal conditions. If software manipulation users decide to scan photos, the computer allows them to use photo manipulation software to make changes. However, the quality of a scanned photo can be lower than that of a digital image. The reason for this is the pixelation in the image.

When zooming in on an image, a person can see blocks of color, or pixels. Higher quality images have more pixels, or more small blocks of color that can be used to represent a wider spectrum. When a scanner scans a color document, it does make several passes, using a filter to interpret each color layer (red, blue and green). These layers are then merged to create the color image. In the process of the merger, pixels may lost, reducing quality.

How A Computer Scanner Works: Conclusion

A business or home may use a scanner to archive text documents or photos composed prior to the age of scanners. Through a complex series of diodes, the CCD and computer software, a user can enjoy the benefits of a scanner, opening up a door to new possibilities.


  1. Ray
  2. Liane Markus
  3. kathleen
  4. Sarthak Kaushik
  5. Peter