Display motion blur

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Display motion blur, also called HDTV blur and LCD motion blur, refers to several visual artifacts (anomalies or unintended effects affecting still or moving images) that are frequently found on modern consumer high-definition television sets and flat-panel displays for computers.

Contents

Causes

Many motion blur factors have existed for a long time in film and video (e.g. slow camera shutter speed). The emergence of digital video, and HDTV display technologies, introduced many additional factors that now contribute to motion blur. The following factors are generally the primary or secondary causes of perceived motion blur in video. In many cases, multiple factors can occur at the same time within the entire chain, from the original media or broadcast, all the way to the receiver end.

Motion blur has been a more severe problem for LC displays, due to their sample-and-hold nature. [3] Even in situations when pixel response time is very short, motion blur remains a problem because their pixels remain lit, unlike CRT phosphors that merely flash briefly. Reducing the time an LCD pixel is lit can be accomplished via turning off the backlight for part of a refresh. [4] This reduces motion blur due to eye tracking by decreasing the time the backlight is on. In addition, strobed backlights can also be combined with motion interpolation to reduce eye-tracking-based motion blur. [5] [6] Timing when a pixel is lit can also reduce the effects of a slow pixel response time by turning it off during the transition or overshoot.

Fixes

Strobed backlights

Different manufacturers use many names for their strobed backlight technologies for reducing motion blur on sample-and-hold LCDs. Generic names include black frame insertion and scanning backlight.

Motion interpolation

Some displays use motion interpolation to run at a higher refresh rate, such as 100 Hz or 120 Hz to reduce motion blur. Motion interpolation generates artificial in-between frames that are inserted between the real frames. The advantage is reduced motion blur on sample-and-hold displays such as LCD.

There can be side-effects, including the soap opera effect if interpolation is enabled while watching movies (24 fps material). Motion interpolation also adds input lag, which makes it undesirable for interactive activity such as computers and video games. [18]

Recently, 240 Hz interpolation have become available, along with displays that claim an equivalence to 480 Hz or 960 Hz. Some manufacturers use a different terminology such as Samsung's "Clear Motion Rate 960" [9] instead of "Hz". This avoids incorrect usage of the "Hz" terminology, due to multiple motion blur reduction technologies in use, including both motion interpolation and strobed backlights.

Manufacturer Terminology:

Laser TV

Laser TV has the potential to eliminate double imaging and motion artifacts by utilizing a scanning architecture similar to the way that a CRT works. [25] Laser TV is generally not yet available from many manufacturers. Claims have been made on television broadcasts such as KRON 4 News' Coverage of Laser TV from October 2006, [26] but no consumer-grade laser television sets have made any significant improvements in reducing any form of motion artifacts since that time. One recent development in laser display technology has been the phosphor-excited laser, as demonstrated by Prysm's newest displays. These displays currently scan at 240 Hz, but are currently limited to a 60 Hz input. This has the effect of presenting four distinct images when eye tracking a fast-moving object seen from a 60 Hz input source. [27]

There has also been Microvision's Laser MEMS Based Pico Projector Pro, which has no display lag, no input lag and no persistence or motion blur. [28]

LED and OLED

Both OLED and Sony's Crystal LED displays use an independent light source for every pixel, without a traditional CCFL or LED backlight used in LCD. Sony's Crystal LED [29] uses individual light emitting diodes for each pixel, instead of using LED as a backlight. Several displays demonstrated at the CES 2012 have been the first modern high-definition television sets to overcome the motion artifacts by selectively blanking parts of the screen. [30] Both OLED and "Crystal LED" technologies also have response times far shorter than LCD technology, and can reduce motion blur significantly. However, all consumer OLED displays are sample-and-hold, [2] [31] which leads to the same amount of motion blur as a conventional LCD.

See also

Related Research Articles

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<span class="mw-page-title-main">Liquid-crystal display</span> Display that uses the light-modulating properties of liquid crystals

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not emit light directly but instead use a backlight or reflector to produce images in color or monochrome.

<span class="mw-page-title-main">Flat-panel display</span> Electronic display technology

A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment.

The refresh rate, also known as vertical refresh rate or vertical scan rate in reference to terminology originating with the cathode-ray tubes (CRTs), is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate, which describes how many images are stored or generated every second by the device driving the display. On CRT displays, higher refresh rates produce less flickering, thereby reducing eye strain. In other technologies such as liquid-crystal displays, the refresh rate affects only how often the image can potentially be updated.

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References

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  20. LG's TruMotion terminology
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  24. Sharp's AquoMotion terminology
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  31. Why Do Some OLED's Have Motion Blur?