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

Simulators Change the Consumer Experience – But is that a Good Thing?

At PC Tech Guide, we have written extensively about the role of virtual reality. Virtual reality has changed the way we interact with games. It has helped flight schools better prepare pilots to thrive in their careers. Demand for virtual reality products is growing at a tremendous pace. The Sony … [Read More...]

RAID tutorial – installing the drivers

Now is the time to use the previously prepared floppy disk containing the RAID Controller driver software. Proceed as follows: Press F6 when invited to do so, to ...... install third party SCSI or RAID driver. Press S when invited to do so, to specify additional SCSI adapters, CD-ROM drives, … [Read More...]

PcSync Review

PcSync Review

PROS: The file shredder worked, albeit very slowly. CONS: As the long time runner in the data transfer market, LapLink's PCsync still offers a good product. Business users will find the software suitable in office environments. Home users with limited computer knowledge may find the … [Read More...]

AI-Driven Software Improves Trading Strategies for Investors

Artificial intelligence technology is changing the state of modern finance. A growing number of investors are utilizing AI to improve the … [Read More...]

What You Need to Know When Choosing the Best VPN for an iPhones

Today millions of people have smartphones; most use them to access the Internet. Research shows that more than 50% of Internet users access it with … [Read More...]

Must-Have Software and Apps Every Remote Worker Should Have on Their PC in 2023?

In the last few years, the future of work has changed permanently. In a survey conducted near the end of 2020, 72% of people were fully remote, with … [Read More...]

Cloud Technology Changes the Calculus of Risk Management in a Global Economy

Cloud technology has changed the state of the global economy in previously unimaginable ways. Ninety-four percent of enterprises utilize some form of … [Read More...]

Risk Management Considerations in an Artificial Intelligence Environment

Risk management is about identifying, assessing, evaluating, and prioritizing risk. Although risk management has been practiced in some ways since … [Read More...]

New Software and GPS Tools Help Parents Monitor their Children

More parents are using technology to keep their children safe. One survey from Pew Research in 2016 showed that 30% of parents use technology to block … [Read More...]

Guides

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

Recent Posts

Web Searches-Browser Hijacker Infection

The adware Web Searches are made to carry out multiply task not to benefit the users, but its sponsors and gain revenue. This is the sad reality of a … [Read More...]

What is an Antidetect Browser and how can it protect you?

To be everywhere and to be nowhere - it is the purpose of many users on the Internet making modern advertisement campaigns. Many websites banned the … [Read More...]

Motherboard Fan

In this case, the motherboard has two fan pin headers in addition to the CPU fan, designated as follows: JP2: System fan JP15: Power … [Read More...]

[footer_backtotop]

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