Mar
31
Upconversion
Filed Under Terminology | Leave a Comment
A lot has been said about upconversion and I’m sure a lot remains to be said. Personally I find it to be of little benefit, at least as it’s typically utilized in low-end to mid-range consumer electronics. There are some great examples of pro-broadcast upconverison but that’s of little use to the enthusiast.
Upconversion can be found in several different forms, DVD players can up-convert standard definition DVD’s to output at resolutions of 720p, 1080i, or even 1080p, but just keep in mind that resampled pixels are no substitute for more “real” pixels. Upconversion can also be found (increasingly) in surround receivers. This is a broader catch-all approach and obviously offers you the ability to upconvert video signals that otherwise would be passed on in standard definition.
The third most common form of upconversion is one that anyone with a digital display has the ability to use right now. It’s called turning on the television and watching anything with a different resolution than the displays native rate. Ok sorry for the sarcastic example but it’s true. All digital displays upconvert to some degree or another, if they didn’t you’d see 480i/p and 720p as a (postage stamp) “window” inside 1080p displays. You’ve seen that very thing you say? In all likelihood that was improperly flagged video or double pillar boxed (both vertically and horizontally) by the broadcaster.
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Mar
2
Contrast Ratio
Filed Under Terminology | Leave a Comment
I wanted to speak for a second about contrast ratio, as it seems to be one of the most misunderstood display measurements among consumers I’ve encountered. In a nutshell, a displays (be it plasma, LCD, DLP, SXRD etc) contrast ratio is the difference between the brightest image the display is capable of rendering versus the darkest. With that, it’s pretty easy to see why you’d want the highest contrast ratio possible. Just imagine high-noon in a western versus the darkest night possible in a horror movie and everything in-between.
Ok, so now we all know that (in theory at least) the higher the contrast ratio the better, so all we have to do is pick the display with the highest overall contrast ratio and the stars and planets will align right? If only it were that simple. Manufacturers are notorious for finding some pretty creative ways imaginable to get the best test results possible. This includes using tweaked product samples, conducting the tests in less than real word environments, and outright deception.
I generally advise clients to think of contrast ratios as a starting point, not the final destination. If you’re comparing model (a) to model (b) from the same manufacturer that’s fine, the numbers will generally be accurate but you’ll want to see a display first hand before making any judgment based on contrast ratio with displays from different manufacturers.
Feb
26
Digital Light Processing (DLP)
Filed Under Front Projection, Terminology | Leave a Comment
In order to discuss the different display technologies effectively (at a later date) we’ll need to define some of them upfront. I could have started with LCD, plasma, D-ILA, SXRD or any number of others but I wanted to start with DLP (Digital Light Processing) as its one of the most common front projection technologies in use and well, front projection is just plain cool. DLP was developed by Dr. Larry Hornbeck at Texas Instruments in the late eighties but believe it or not front-projection wasn’t one of the first implementations. It (DLP) was actually used to fuse red dyes (text and images) onto airlines tickets.
DLP uses millions of moving micro-mirrors to create the images we see on-screen, the mirrors are fixed to a chip called a Digital Micromirror Device (DMD) which is illuminated by the projectors lamp (gross oversimplification). The technology is known for its accurate colors, sharp images and often better than average contrast ratio.
DLP’s create color by focusing the light path through a color-wheel; multiple “colors” are projected by varying the speed of the color wheel. Early DLP’s were prone to smear colors (known as rainbow effect) due to the slow speed of color-wheel but this was all but eliminated in recent models by higher-speed, multi-segmented color wheels.
3-chip DLP projectors eliminate the color smearing problem altogether with the use of one DMD per primary color, i.e. red, green and blue. 3-chip DLP’s are quite expensive when compared to their single-chip counterparts but are generally perceived as superior in all regards.