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Optoma HD91 Projector - Special Features 2

Posted on June 11, 2014 by 
OPTOMA HD91 PROJECTOR - SPECIAL FEATURES PAGE 1:  Pure Color, UltraDetail, Dynamic Black

Pure Color

Pure Color – I haven’t quite figured out all the different factors at play, but the higher you dial it up the more vibrant the colors.  The question is at what point does it become over the top.  The control itself offers five steps, plus off.  Mostly I left it in default but when playing with it I wasn’t happy going above 3 on some content, 2 on others. Again, your decision will be based on what you like vs what is technically ideal.  And that’s “OK”.

I suspect that Pure Color is BenQ's custom implementation of TI's Brilliant Color, which the DLP folks have been making available to the DLP projector manufacturers for many years now.


UltraDetail performs as a dynamic detail enhancement solution, similar to those from Epson and others.  I would put it this way, the projector is attempting to sort through the and reprocess the data to reveal missing detail, but it’s a guessing game.

Taking 2K (1080p) data, for example, and upscaling to 4K, applying algorithms and then downscaling back to 1080p may give the perception of more detail, but it’s still not the real detail that true 4K content would have on a 4K projector.  None the less, dynamic detail enhancement is becoming a standard feature, at least on most new $2000+ home theater projectors.

A purist, in theory, would not engage Ultra Detail, but whether Ultra Detail or some other brand’s attempt often provide the look of more slightly sharpness and detail, which many will find attractive.  Better of course, that we quickly get to affordable true 4K projectors, as our “need” for such dynamic detail enhancement features, is mostly due to the current “low” resolution standard of 1080p.   1080p may be gorgeously sharp and clear on a 65” LCDTV viewed at 12 – 20 feet (which is typical), but 4K (aka Ultra-HD) has four times the resolution, and that’s really needed for a really sharp picture on a 100” screen viewed at 8-10 feet, for serious “theater like” immersion.  Bottom line:  try it, use judiciously.

The first setting should be acceptable, it certainly is for action flicks etc. but a tends to look “hard” at times.  I wouldn’t normally recommend the higher setting HD+.  I’d call it over the top. But, to each his own.  These images were taken with UltraDetail On, but not on HD+.

Dynamic Black Performance - Light Source Dimming

Dynamic Black in the HD91 is what would normally be called a lamp dimming solution, but this is an LED projector not lamp.  There are three settings, aptly named Dynamic Black 1, 2, and 3.  And, Off, of course.

In this case Dynamic Black has the same function as traditional dynamic irises.  Dynamic 1 offers the least amount of dimming range, so has the least, but still significant effect on dark scenes.  DB3 offers a lot more range and delivers a darker scene.  DB2 in the middle sometimes seems to behave like DB1 other times more like DB3.

My issue is that the "iris action" (or dimming action) is somewhat slow and often too noticeable.  That's more of an issue with DB3 than with DB1.  Interestingly, even moderately bright scenes show the action.  Let's start there.  In our player is a sequence of the Russian Ambassador in Hunt for Red October.  I used the Epson (right side) for a "control".  Note the change in brightness of the man's face, and also the mantle behind him on the Optoma over a few frames.   The Optoma, when this scene opens, starts bright and dims down a bit, and you can see that when watching, and when looking at these images.  Any Epson change is minimal by comparison.

Similar occurs in dark scenes.  If you look at the three images taken a second or so apart in the bond train scene, again, a very visible change in overall brightness on the Optoma and little on the Epson.  In both sets of images DB3 was used, but DB1 exhibited similar behavior except to a lesser degree.

Many casual viewers may not notice the lamp dimming action, but for enthusiasts who tend to notice "everything" this could be a deal breaker.

You do have the option of turning Dynamic Black off.  What confuses me (not being an engineer) is why the light source dimming seems slow.  That tended to be a problem with lamps, but I would have thought an LED light source to be especially fast.

Optoma could take this projector up a full performance notch if they can get their Dynamic Black to function as smoothly as the Epson or the Sony HW55ES.


In these last two images, once again the Epson (right) is our control.  The first image is Dynamic Black Off, followed by Dynamic Black 3.

The goal of these two starship images was not to compare against the Epson.  You'll notice that the brightness of the Epson starship is darker than either HD91 image.   But the Epson starship in both images is exactly the same brightness, showing that both images were taken with the same exposure.  That results in Dynamic Black 3 having a distinctly blacker "deep space" and letterbox than the Dynamic Black Off image.

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