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Simplex Dimming: providing a new generation of locally dimmed display devices

Ref-Nr: TA-WuT_2013/39


The invention provides an novel and efficient method for dimming a display device at reduced power consumption while maintaining a desired quality of the displayed image.


Local dimming (LD) is an established technique to reduce the power consumed by the multitude of different LEDs that generate the backlight of, e.g., a TV display device. In contrast to global dimming (GD), it acts on the different LEDs individually. The backlight in each pixel of the display may be modeled as a weighted combination of the influences of the different LEDs. Then, the sum of the power of all LEDs may be minimized under the restriction that each pixel achieves its necessary brightness aiming to achieve an energy-efficient dimming level of each individual LED of the display.

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Known solutions to this problem suffer from different drawbacks in terms of non-optimal efficiency and image quality.


Our new approach adapts the well-known simplex algorithm to obtain an appropriate iterative algorithm for locally dimming a multi-lit LED backlight device. It solves the underlying linear minimization problem while additionally fulfilling advantageous relations between the brightness levels of different LEDs. E.g., the first and/or higher order derivatives of the solution can be restricted, which is a very natural demand. The method not only calculates a LD solution with a high power saving but also with a high correlation of the image and the backlight in one step. The invention gives a warm start strategy which is very useful for movies to reduce the iterations to very small numbers. As the algorithm has a parallel structure in contrast to the sequential approaches of known state-of-the-art algorithms, computation time can be further reduced.


  • Smoothness: the algorithm allows for taking into account the brightness levels between of different LEDs and thus avoids “spotlights”
  • Efficient & natural: the algorithm guarantees the energy-efficient solution while fulfilling the demanded brightness relations and providing high correlation of the image and the backlight in one step
  • Speed-Up: warm start strategy for movies reduces iterations
  • Computation efficiency: the algorithm can be efficiently implemented (parallelized) on GPUs reducing processing time
  • Variability: the algorithm can be adapted to both direct- and edge-lit displays


edge-lit/direct-lit display devices, GPUs

Universität des Saarlandes Wissens- und Technologietransfer GmbH

Dr. Christof Schäfer
0681 302-6383
Universität des Saarlandes Wissens- und Technologietransfer GmbH, Campus, Gebäude A1 1
66123 Saarbrücken




  • LU 92598 erteilt
  • US 15/525,430 anhängig

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