AVS HD 709 - Blu-ray & MP4 Calibration - Page 14

I haven't adressed HTPC, because honestly calibration there is more complex. You're dealing with a number of different decoders depending upon format, that part I'm somewhat sure about and there are some other items I'm not so clear on. With Blu-ray and HD DVD players basically we're making the assumption that mpeg2, AVC, and VC-1 will be correctly decoded to the same levels by the player. I've seen on my computer though that mpeg2 doesn't always necessarily match AVC levels, so I have to attribute that to the different decoders. Even using the PowerDVD trial, with my ATI card (known to have issues with affecting levels) I was running into apparently different levels based on the source type.

Basically where I'm going here is that it's probably more important on a computer, than a standalone, for the source to match the type of material you'll be playing back. If you're mainly playing back DVDs, then it seems to me that a DVD calibration disk would make more sense. If you're playing back recorded ATSC or QAM which might be HD mpeg2, then you probably want a HD mpeg2 source. The HD DVD here is mpeg2, but the container is basically specific to HD DVD. Generally if HD mpeg2 playback is what you use your computer for, then patterns at w6rz.net might make more sense because they're .ts which will likely be closer to the format of your meda.

If you were running HD DVD and Blu-ray on your computer I'd have a different response, but that wasn't the impression I got from what you wrote. All of these disks do originate from mpeg2 files outside of the Blu-ray and HD DVD formats, but currently we have not been hosting those files and it would be something that would have to be discussed. Honestly though, there are probably tools available to split the HD DVD and Blu-ray videos into more common formats that would play back on your current software if you are trying to calibrate for playing back HD files on your computer.

Generally for a first run you'll want to begin by setting the display's user controls with the Basic Settings area. Then you can "measure gray scale, primary, and secondary colors" with HCFR. The patterns which correspond to that selection in HCFR are the 10% Grayscale and 100% color sections on the disk. That will fill in all the charts on the left of HCFR that you can use to give you an initial impression of how the display is generally performing. If you're not familiar with how to read the charts, then I found http://www.avsforum.com/avs-vb/showthread.php?t=586691 useful when I first tried HCFR.

Measurements - When you make a selection under view with HCFR v2, it will list what patterns are expected for those measurements. To start out with, just try running the "gray scale" and then the "primaries and secondaries" measurements using the "10% Grayscale" and "100% Colors" sections from the disk. In the end, the only practical use of any reading here is if it helps you get your display closer to intended standards.

Windows vs. fields - Generally for most uses windows are fine. Maybe there are uses for fields, but the disk is mostly centered around windows because from what I've read more displays will run into fewer issues running windows than might happen for fields.

Terminology - I generally use the definitions from TomHuffman's CMS thread. Although Avia defines saturation differently, I just ignore the Avia definition and use the ones from that thread. On a Sony color is probably a luminace control, it's just a brightness control for color.

IRE vs Percentages - If you keep things digital like using HDMI or DVI then IRE is completely irrelevant. Again Avia is sort of the odd duck out because they use IRE while most everything else uses percentages. Even if you're using component, which is analog where IRE applies, I think for most applications it's entirely fine to discuss things by percentages and not to worry about understanding what IRE really means.

My last TV, that had color decoder controls, had a little bit of difference between 100% measurements and 75% measurements. I thought that http://www.avsforum.com/avs-vb/showthread.php?t=852536 used to address this item, but it really doesn't now. My impression was that 75% might be considered a little closer to average program material. The reason this disk includes both is just that on the last version of HCFR there wasn't an option to measure gray with colors (to look at color decoding), so it was easiest to do a 100% color run right after a 10% grayscale run. In the end I'm not sure it really matters one way or another, because the differences weren't very far apart on my TV.

They probably are meant to mean the same. Most people don't use IRE exactly as it seems to be defined. At the end of the GetGray documentation http://www.calibrate.tv/docs/GetGrayCalDiscReadme.zip there is some information about IRE. In one of the postings here by ChrisWiggles there are more technical details like analog voltages and such things. Personally I have no use for the word IRE because almost all of my sources are digital connections.



Saturation as defined in the CMS thread generally seems to be how far from white a point appears in xy coordinates. If a xy coordinate is at red that would be 100% saturated red and a gray would be 0% saturation as far as I can tell.

Hue as defined there is basically how an xy coordinate relates to white by angle. After you can take measurements you'll find that by changing the hue control that the secondaries will move along the CIE triangle, which changes the angle in relation to white.