Skip to main content

Image Enhancement

  • Living reference work entry
  • First Online:
Handbook of Visual Display Technology


When using displays outdoors, the readability of the content shown can degrade at large extent by reflections of bright ambient light, like on a sunny day outdoors. Technically speaking, the display’s luminance and the reflected luminance of ambient light superimpose in the eyes of an observer. Therefore, display quality parameters (contrast ratio, grayscale, and colour reproduction) are perceived significantly lower as indoors or the values provided in data sheets, which are measured under dark room conditions (no ambient light). Additionally, the effect of superposition is degrading the “darker” (lower gray levels) relatively more than the “brighter” content on displays.

This affects, besides mobile personal devices, many applications like displays in cars and e-signage (such as information terminals, signs, kiosk applications). There are many possibilities to enhance the image quality of a display for bright ambient light: high luminance of the display, reflection reduction, blocking ambient light by shields, or raise lower gray levels.

The latter method, which is called “image enhancement,” is presented here. Its advantage is that the costs are significantly lower compared to the other improvement methods as being only software based. Generally speaking, the original gamma value (typical γ = 2.2) is lowered so that the value of a low gray level, e.g., 50 (of 256 for 8 bit grayscale depth) is raised to, e.g., 70. There exist several methods, which are presented and discussed here. They differ basically in terms how the gray levels are modified and the artifacts which might occur. An essential point is that the colour of the original image should be kept as best as possible. However, image enhancement has its limits when, e.g., the luminance of the display is too low.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Institutional subscriptions

Similar content being viewed by others


CIE 1931:

Colour standard issued 1931 by the Commission International d’Eclairage


Colour management

Cr :

Contrast ratio

EAmb :

Illuminance of ambient light on a display surface


Grey level or value


High Dynamic Range


Human Machine Interface


International Telecommunication Union




Liquid Crystal (Display)


Low Dynamic Range

LR :

Reflected luminance of ambient light (EAmb) by a display surface


Red green and blue primaries of a colour display


Tristimulus coordinates of CIE


Abbreviation of CIE 1931 coordinates with Y as luminance


Gamma value


Weber’s fraction for luminance difference and luminance


  • Blankenbach K, Sycev A, Kurbatfinski S, Zobl M (2014) Optimizing and evaluating new automotive HMI image enhancement algorithms under bright light conditions using display reflectance characteristics. JSID 22(5):267–279

    Article  Google Scholar 

  • Cho H, Youn J, Choi M (2004) An image enhancement algorithm for flat panel display. In: Proceedings of IDW’04. pp 1591–1594

    Google Scholar 

  • Kykta M (2008) Understanding gamma correction for high dynamic range displays. SID 39(1):1336–1338

    Article  Google Scholar 

  • Mantiuk R, Daly S, Kerofsky L (2008) Display adaptive tone mapping. ACM Trans Graph (Proc SIGGRAPH) 27(3):68.1–68.10

    Article  Google Scholar 

  • Mantiuk R, Myszkowski K, Seidel H (2015) High dynamic range imaging. In: Wiley encyclopedia of electrical and electronics engineering. pp 1–42. Wiley, New York

    Google Scholar 

  • Sasaki H, Taguchi T (2003) Perceptually linear gamma correction for LCDs. JSD 34(1):936–939

    Google Scholar 

  • Xu X, Kerofsky L (2011) Improving content visibility for high-ambient-illumination viewable display and energy-saving display. JSID 19/9:645–654

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Jan Bauer .

Editor information

Editors and Affiliations

Rights and permissions

Reprints and permissions

Copyright information

© 2015 Springer-Verlag Berlin Heidelberg

About this entry

Cite this entry

Bauer, J., Sycev, A., Blankenbach, K. (2015). Image Enhancement. In: Chen, J., Cranton, W., Fihn, M. (eds) Handbook of Visual Display Technology. Springer, Berlin, Heidelberg.

Download citation

  • DOI:

  • Received:

  • Accepted:

  • Published:

  • Publisher Name: Springer, Berlin, Heidelberg

  • Online ISBN: 978-3-642-35947-7

  • eBook Packages: Springer Reference EngineeringReference Module Computer Science and Engineering

Publish with us

Policies and ethics