Technical Articles and Editorials
- Written by Chris Heinonen
- Published on 08 May 2013
For The Reviewer
As a reviewer, I want different things that most users do. Most test discs are only structured for the end user, and getting some of those initial settings correct, and not for the reviewer or someone trying to seriously evaluate a product. Thankfully Spears & Munsil come from a background of evaluating a product to determine its performance, not just to get it setup correctly, and there are a ton of features in there to help me in my job, and help you find out what all a product can do.
One request I made to Stacey Spears was to include this uniformity test pattern, which is found in EBU Tech 3325. Using 13 squares located all around the screen, I can determine if the light output of a display or projector is uniform everywhere, or if it's too concentrated in the center. Usually people just measure the center of the screen, but in projectors, the cheaper the lens the less uniform the light output will be across the screen. Expensive lenses take expensive glass and most people don't realize the cost of getting a better lens on a projector, but this helps to measure this and show it to the reader.
Similarly, with 3D reviews we have been forced to rely on describing material that we have seen and hoping those artifacts that we see are caused by the display and not from the material itself. Now we can use these 3D test patterns to determine the amount of crosstalk in a 3D display and be certain it is from the display and not the source, and more easily use this number to compare different devices. We still watch 3D content, of course, but this is bringing an objective measurement to our subjective opinions.
One under-measured feature of displays is how well they handle motion. LCD and Plasma displays might both be 1080p, but that is with a still image. Start to have objects that move and LCDs will quickly start to smear details, while plasmas will remain sharper. With OLED and other technologies coming out, this will become more important for people to test to see the distinction in those.
I can also use these tests to evaluate the motion interpolation that many sets offer. Often you'll start to see sharper details when it's enabled, but also see artifacts that appear at the same time. Being able to partially quantify the benefit they offer but also see the drawbacks helps us to communicate how these perform to our readers. These patterns let us begin to assign numbers to a topic like motion, and let you easily see the difference with different settings enabled.
There are also a number of useful color ramps in Spears & Munsil that don't really let you calibrate off them or fix anything, but show the errors in the color handing of your display. For example, I can find that my display does blue perfectly, but red and green have slight bits of banding introduced into them. It isn't possible to correct this, at least without expensive outside video processors possibly, but it lets me better evaluate a display and decide how well it works, and if I should recommend it to readers or not.
Another problematic area for me as a review is evaluating scaling on a display device or Blu-ray player. I can go back to DVD transfers that I thought were incredible back then, like The Incredibles, but then I enter a realm of being purely subjective, and possibly not always looking at the exact same frame as before. On Spears & Munsil there is now a scaling test image, available at 480, 720, and 1080 resolutions, which has definite criteria to meet. Certain parts of the image should scale a certain way, and other objects in the image are designed to cause ringing, moiré, and other artifacts in poorly designed scalers. It still is a bit subjective, without a number we can assign to it, but it does have certain features that let us assign a passing or failing grade to a device we are testing.