For a long time, the dirty little secret in LCD flat panel TVs was its inability to refresh fast enough to avoid on screen motion artifacts characterized as "motion blur." Anyone who has done their homework before shopping for one of these thin-flat-bright and beautiful displays has known to ask the salesman: "…what is the (rise-fall) response time?" with the knowledge that faster (smaller numbers usually in milli-seconds) were better.

Steve Sechrist
Senior Analyst and Editor

Well, now! Independent testing guru, Dr. Raymond Soneira and his DisplayMate Technologies Corp., in collaboration with Insight Media, takes a look at this issue in a recent technology review. Soneira’s report "LCD Response Time and Motion Blur" makes the happy conclusion that: "[T]here was no notable difference in motion blur between the top-of-the-line models (which all had 120 Hz refresh or LED strobing) and the mid-line models (which all had standard 60 Hz refresh), and which cost less than half of the high-end models.

This conclusion was "consistent across the board" from "everyone that participated in the image evaluation. When people thought they saw motion blur, with only a handful of minor exceptions, the blur was either in the source video or a temporary visual illusion that disappeared when the segments in question were reviewed."

The interesting point to this research is, even with all of these recent image improvement technologies from LCD makers, the report documents photographic evidence of motion blur on LCDs when static images are scanned across the screen at various speeds.

Soneira also conducted a human viewing test that included 8 LCD TVs, 2 plasma TVs and a Sony Professional CRT monitor as the reference standard. Various types of video were used and viewers were allowed to compare questionable scenes multiple times using a TiVo. It seems the complex nature of live action video on the display eliminates all perceptible motion blur, giving the LCD-TV makers a stunning, fast motion, blur-free image. This occurs even in TVs without 120 Hz refresh rates, strobed LED backlighting, or advanced motion enhancement processing, according to the findings.

Here’s Soneira’s explanation: "Unlike the moving test patterns and moving photographs, the eye is unable to detect the blur in live video because the images are much more dynamic and complex, and undoubtedly because of the way the brain processes and extracts essential information from visual images."

Soneira said when it comes to true picture quality improvement, some of the more traditional approaches often do more harm than good. "Most either introduce objectionable artifacts into the images or are just ineffective marketing gimmicks." Soneira said. These include methods like pixel "overdriving" (temporarily exaggerating the drive voltage to give the liquid crystal "…an extra hard kick in the pants") or "edge enhancement" (using high frequency peaking) or even the popular approach of increasing the refresh rate from 60 Hz up to 120 Hz or more.

We asked Soneira about the timing of LCDs progress in overcoming motion blur and when did the technology get to the point where the response time was no longer creating motion artifacts visible to the human eye? Soneira said "LCD motion blur has been steadily decreasing over the last decade. In the last few years it has decreased to the point where it is no longer detectable in live video, so further improvements are no longer necessary…"

While at first sight Soneira’s results might appear to antagonize the large consumer brands, the real message here is that the manufacturers have finally beaten the motion blur problem. So both consumers and manufacturers can forget about this and move onto the more productive technical and marketing issues for the next generation of 3D displays.

If you take Soneira’s advice, forget the marketing hoopla and simply go for "mid to top tier models from the reputable brands, you should ignore Response Time specifications, not worry about LCD motion blur, and don’t spend extra for 120 Hz or higher refresh rates, strobed LED backlighting, or advanced motion blur processing." With the extra money you save, how about a nice Blu-ray disc player… - Steve Sechrist
(Ed. Note: Look for an expanded version of this story complete with the full details on test procedures and results in the November Issue of Large Display Report)