pctechguide.com

  • Home
  • Guides
  • Tutorials
  • Articles
  • Reviews
  • Glossary
  • Contact

Scanner File Formats

The format in which a scanned image is saved can have a significant effect on file size – and file size is an important consideration when doing some image and document scanning, since the high resolutions supported by many modern scanners can result in the creation of image files as large as 30MB for an A4 page.

Windows bitmap (BMP) files are the largest, since they store the image in full colour without compression or in 256 colours with simple run-length encoding (RLE) compression. Images to be used as Windows wallpaper have to be saved in BMP format, but for most other cases it can be avoided.

Tagged image file format (TIFF) files are the most flexible, since they can store images in RGB mode for screen display, or CMYK for printing. TIFF also supports LZW compression, which can reduce the file size significantly without any loss of quality. This is based on two techniques introduced by Jacob Ziv and Abraham Lempel in 1977 and subsequently refined by Unisys researcher Terry Welch. LZ77 creates pointers back to repeating data, and LZ78 creates a dictionary of repeating phrases with pointers to those phrases.

CompuServe’s graphics interchange format (GIF) stores images using indexed colour. A total of 256 colours are available in each image, although what these colours are can change from image to image. A table of RGB values for each index colour is stored at the start of the image file. GIFs tend to be smaller than most other file formats because of this decreased colour depth, making them a good choice for use in WWW-published material.

The PC Paintbrush (PCX) format has fallen into disuse, but offers a compressed format at 24-bit colour depth. The JPEG file format uses lossy compression and can achieve small file sizes at 24-bit colour depth. The level of compression can be selected – and hence the amount of data loss – but even at the maximum quality setting JPEG loses some detail and is therefore only really suitable for viewing images on-line. The number of levels of compression available depends on the image editing software being used.

Unless there is a need to preserve colour information from the original document, images stored for subsequent OCR processing are best scanned in greyscale. This uses a third of the space of an RGB colour scan. An alternative is to scan in Line art mode – black and white with no greyscales – but this often loses detail, reducing the accuracy of the subsequent OCR process.

The table below illustrates the relative file sizes that can be achieved by the different file formats in storing a native 1MB image, and also indicates the colour depth supported:

File format Image size No. of colours
BMP – RGB 1MB 16.7 million
BMP -RLE 83KB 256
GIF 31KB 256
JPEG – min. compression 185KB 16.7 million
JPEG – min. progressive compression 150KB 16.7 million
JPEG – max. compression 20KB 16.7 million
JPEG – max. progressive compression 16KB 16.7 million
PCX 189KB 16.7 million
TIFF 1MB 16.7 million
TIFF – LZW compression 83KB 16.7 million
  • Scanner Operation
  • PMT Scanners
  • CCD Scanners
  • CIS Scanners
  • Scan Resolution
  • Scanner Interpolation
  • Color Scanners
  • Bit-Depth Printers
  • Dynamic Range Scanners
  • Scan Modes
  • Scanner File Formats
  • TWAIN Drivers
  • Color Calibration
  • OCR Technology
  • Photo Retouching

Filed Under: Scanners

Latest Articles

Virtual Memory

Video Covering Virtual Memory - Part of our Fix Slow Computer tutorial found on  https://www.pctechguide.com/how-to-fix-your-slow-computer Transcription From Video Hi, this is Jacob with pctechguide.com. In this video series, we're covering how to speed up your slow computer and this is … [Read More...]

Fatal Exception OE Errors

Anybody who owns a PC has probably seen enough error screens to last a lifetime. Out of all of these possible error messages, one of the most annoying continues to be the fatal exception OE error screen. The reason that fatal exception errors are so annoying is because there are so many … [Read More...]

FusionPlayer

The whole premise of FusionPlayer is that it will let you create media play lists using videos on the computer and videos from the Internet. That is its hook and the incentive to install the program. The truth is, however, this is a PUP (potentially unwanted program)that is nothing more than a … [Read More...]

Why Cross-Chain Trading Is the Future of Crypto Investing?

The rapid growth and evolution of the cryptocurrency market have opened up exciting opportunities for investors. Within this dynamic landscape, … [Read More...]

Revolutionize Your Internet Experience with Orbi 960 – The Ultimate WiFi System

In a world where seamless connectivity is essential, slow and unreliable internet connections are a major problem. Whether you are running a business, … [Read More...]

Do You Need a VPN When Trading Cryptocurrency?

There’s no doubt that the biggest global industries in 2023 are tech-driven, while there remains a significant crossover between many of these … [Read More...]

Goodbye Bitcoin: the 3 alternative cryptocurrencies that have great upside potential, according to experts

Bitcoin has been a very lucrative investment for people that got into it early. One report from The Motley Fool pointed out that $10 of bitcoin … [Read More...]

Self-driving cars face their Achilles’ heel and may be targets of hackers

The market for self-driving cars is booming. Customers spent $22.22 billion on these autonomous vehicles in 2021 and they will likely spend more in … [Read More...]

How to avoid scams with bitcoin and other cryptocurrencies

Cryptocurrencies got a bad reputation when scams multiplied like ants on a piece of cake. Even today many people associate bitcoin and other … [Read More...]

Guides

  • Computer Communications
  • Mobile Computing
  • PC Components
  • PC Data Storage
  • PC Input-Output
  • PC Multimedia
  • Processors (CPUs)

Recent Posts

HR Software Market to Reach $30 Billion as New Solutions Introduced

The market for HR software applications is growing at a tremendous pace. One study predicts that the market will be worth $30 billion by 2025. The … [Read More...]

A Peak at the Lumia 950

Its coming. The new phone from Microsoft, the Luma 950 is due any time now. This will be the flagship Windows phone and Microsoft will be unveiling it … [Read More...]

Joysticks

A joystick is a PC peripheral or general control device consisting of a handheld stick that pivots about one end and … [Read More...]

[footer_backtotop]

Copyright © 2023 About | Privacy | Contact Information | Wrtie For Us | Disclaimer | Copyright License | Authors