New calibration disc

[Ursa]

Originally Posted by gregr

But if you created patterns with black at RGB-Video (16,16,16) then it appears that this was really about how to represent values below black, not how to represent black. And in that case, I guess the question was how to represent a below black RGB-Video (0,0,0) value as a YCbCr value. The answer to that is simple. You can't in Rec 601. The RGB-Video (0,0,0) value is reserved in Rec 601 and shouldn't be used as a video value on a DVD. The minimum value you should use is RGB (1,1,1) which is YCbCr (1,128,128). (I'll resist the impulse to ask why you want to encode signals that far below black in the first place).

Greg - I think we are on the same page. Scott had asked me why RGB(0,0,0) was illegal. My response was that was what was in the Rec. I also did not know whether YCbCr(0,0,0) was illegal, but that seems to also be what the Rec says (the free copy is pretty sparse on explanatory language for us lay people). I'd leave it up to Scott for anything else, since I wasn't a participant in the discussion beyond just what the Rec says.


Later,
Bill

[GetGray]

Greg, I believe I answered incorrectly re "that's exactly what I do". It is not. Let's see if this helps. Here IS what I do.

Take for example a 0% amplitude pattern. It has a window that is encoded as RGB 16/16/16. The "frame" of that window is intentionally encoded below black, the maximum below. The original pattern's frames were created using RGB 0/0/0. Ursa suggested that technically this shoudln't be done and it would be more proper to use 1/1/1. Whether or not this is correct may be technically moot since no one's properly calibrated display is going to show levels of 1 or 0, valid or not.

To create the pattern, I take the RGB (photoshop) image and convert it to YCbCr studio levels using a C program. This YCbCr is fed to an mpeg encoder that accepts YCbCr natively, and created the mpeg structure from it.

RGB 0/0/0 converts to YCbCr 0/128/128 with my C program. This is meant to be "below black" information, and the lowest value of below black possible. Also, the mpeg encoder is set to accept values 0-255 so it does not clip the <16 information back to 16.

For a "0% amplitude" video black window, the level is RGB 16/16/16. That is converted to YCbCr as 16/128/128 before being encoded to mpeg.

The disc is intentionally created to be able to show above white (236-255) and below black (0-15) information. It is meant to be used to adjust so 16-235 is the tuned black and white level (+/-).

The issue came about when saying a RGB 0/0/0 (which is converted to YCbCr 0/128/128) was technically a valid level (or not).

Like Dave said, it's academic at this point since if adjusted correctly the display wouldn't get anywhere near actually displaying digital level 1, much less 0. It will clip anything below 16 (or slightly lower if one tuned to allow some BTB to show).

It was whether or not it was correct to use YCbCr 0/128/128 as the lowest possible value of black or was it more correct to use RGB 1/1/1 (YCbCr 1/128/128).

That help clear up what the question/issue was?

[GetGray]

Originally Posted by gregr

But if you created patterns with black at RGB-Video (16,16,16) then it appears that this was really about how to represent values below black, not how to represent black. And in that case, I guess the question was how to represent a below black RGB-Video (0,0,0) value as a YCbCr value. The answer to that is simple. You can't in Rec 601. The RGB-Video (0,0,0) value is reserved in Rec 601 and shouldn't be used as a video value on a DVD. The minimum value you should use is RGB (1,1,1) which is YCbCr (1,128,128). (I'll resist the impulse to ask why you want to encode signals that far below black in the first place).

And I believe that answers the original question, and agrees with Ursa. The "maximum" level of black to be on a DVD in YCbCr should be YCbCr 1/128/128 (RGB1/1/1). For this discussion, call it "Maximum black" unless there is a better/proper name for it.

As to why such a value was used, I knwo I could have used say level 10 for exapmle to be sufficently "below black". I used Maximum Black in places where I wanted to ensure the display was displaying as black as possible. Places where teh display should, in as much as possible, be "off", not giving any color information.

If someone had their brightness too high, a 0% amplitude window would be visible on the darker BTB (and in my disc's case Maximum Black) background. If I was to have a BTB area/element for the sole purpose of being as dark as possible, I decided it might as well be the "Maximum Black" value. In addition to having that level as the background for the gray window patterns, I have one full screen "Maximum Black" window. Those are the only palces I remember having "Maximum Black" off the top of my head.

The Maximum Black pattern is intended to be used to measure on-off contrast. I know this does not account for the brightness setting (if higher), but my intent was to be able to measure a maximum on-off contrast ratio as-calibrated. So if one had their display set to display some below black information, this "Maximum Black" pattern will show that exact level, instead of the brightness of a level 16 pattern which could be slightly higher in luminance, resulting in a worse contrast ratio calculation.

So Claus, I'll straighten out the 0 and 1 thing in my rev.12 and pass back to you.

Greg, thanks very much as always for taking the time to give input.

Everyone else, the "Maximum Black" levels on the current DVD's are already RGB 1/1/1, YCbCr 1/128/128 and are correct.

Cheers,
Scott

[Daryl L]

Originally Posted by CT_Wiebe

Daryl L -- I was concerned that you had missed that fine point in your display's set-up. It sounds like you've covered all the bases with your combinations of set-ups. This is surprising to me, since LCD projectors have the capability of displaying BTB and WTW (at least mine do – including the one I no longer have).

I just looked at my cheap Proview 17" 16:9 LCD TV (in the spare bedroom - Component inputs from the DVD player) and it can’t display BTB either (it also can’t go any higher than 95% on the white level). I did not do any adjusting of the Brightness and Contrast controls on the connected DVD player though (they are set at their defaults). The Proview apparently doesn't do a good job of deinterlacing either, since the Belle-Nuit pattern is only good with the cheap DaeWoo ($50) player set to progressive scan (480p).

Thx anyhow for your input. I had to just edit my previous post to add an important point I left out where my Sharp LCD will infact display a BTB image but only over the HDMI input but just not through the component inputs. I added the below info.

(EXCEPT: through the HDMI input. I have HBOHD's Off Air SMPTE test pattern recorded on my HD DVR Cable box which has below black/video black/above black bars below the color bars and through the HDMI input the Sharp LCD will display the BTB bar). But no matter what combination of settings I use on my LCD and DVD players BTB will not display through the component inputs from the GetGray or DVE discs.

Since this is the wrong thread for this I let it go at that.

[gregr]

Originally Posted by GetGray

... Whether or not this is correct may be technically moot since no one's properly calibrated display is going to show levels of 1 or 0, valid or not.

... The issue came about when saying a RGB 0/0/0 (which is converted to YCbCr 0/128/128) was technically a valid level (or not).

... Like Dave said, it's academic at this point since if adjusted correctly the display wouldn't get anywhere near actually displaying digital level 1, much less 0.

The reason the values 0 and 255 are prohibited isn't related to how a display would show the values. These values are prohibited because they are used to code timing information in the ITU-R BT.656 standard. The BT.656 standard defines a 4:2:2 YCbCr parallel (and serial) interface for transporting video data. One of its applications is to move digital video data between ICs in video products (for instance inside a DVD player between the output of an MPEG decoder and a video DAC or DVI transmitter). Therefore, if you include the values 0 or 255 in the YCbCr video information, it could confuse the sync timing of ICs that receive 4:2:2 YCbCr video using the BT.656 interface (shorten video lines, change the length of fields, etc.). So technically what is prohibited in Rec 601 is the use of the 8-bit values 0 and 255 in 4:2:2 YCbCr video, but since 4:4:4 YCbCr or 4:4:4 RGB values ultimately get converted to 4:2:2 YCbCr for BT.656 interfaces in video products, 0 and 255 must not be used in those formats either.

[CT_Wiebe]

Thank you Greg, you've helped educate me too. From Scott's latest email to me, I believe he's made the corrections.

Scott, I edited it and sent it back (forgot to change the header though). Based on what Greg & Bill said, you need to make sure that your "C" program does not encode 0 or 255 (i.e. it clips at 1 and 254, or even 2 and 253 to be on the safe side).

Daryl L -- I agree. Thanks for the update.

[GetGray]

Originally Posted by CT_Wiebe

Based on what Greg & Bill said, you need to make sure that your "C" program does not encode 0 or 255 (i.e. it clips at 1 and 254, or even 2 and 253 to be on the safe side).

Actually it's more simple than that. I just don't use RGB 0/0/0 when creating. No need to do it programatically. No need to clip, definately not at 2/253. If 1/254 are proper limits for YCbCr, that's exactly what they will be. Actually, black is already set that way. I will change white 255 to 254 in about 3 places.

S

[GetGray]

OK guys. I've released Beta 6.0 Try not to get it all at once. By popular request it has a basic set of full field patterns. I do not recommend their use however unless you have avery specific need and fully understand why you need them over a window pattern.

The current revision of the documentation is also available on the download page to contributors.

Beta 6.0:

Corrected 2 pixel error on "Letterbox" line of alignment/Overscan pattern. Renamed "Letterbox" indicator to more correct 2.35:1
Changed opening screen and disc info/credits
Changed menu wording to Maximum White, Maximum Black.
Added 1 sequence of 10% step full field gray patterns, labelled.
Updated opening screen to production version
Updated credits screen to rolling credits with contributors, info, etc.
Reduced volume on auto gray pattern beeps

Scott

[CT_Wiebe]

You have updated Instructions (just emailed it about a half hour ago). All the errors should be corrected now and all the pictures have been updated too. We're getting there.

I can send you my PDF version, if you desire.

[Anim]

GetGray

Could I join the beta or do you have enough people now?

Thanks
Anim
(TX200 + AE100)

[rickie]

Originally Posted by GetGray

OK guys. I've released Beta 6.0 Try not to get it all at once. By popular request it has a basic set of full field patterns. I do not recommend their use however unless you have avery specific need and fully understand why you need them over a window pattern.

The current revision of the documentation is also available on the download page to contributors.

Beta 6.0:

Corrected 2 pixel error on "Letterbox" line of alignment/Overscan pattern. Renamed "Letterbox" indicator to more correct 2.35:1
Changed opening screen and disc info/credits
Changed menu wording to Maximum White, Maximum Black.
Added 1 sequence of 10% step full field gray patterns, labelled.
Updated opening screen to production version
Updated credits screen to rolling credits with contributors, info, etc.
Reduced volume on auto gray pattern beeps

Scott

Ok, LOL, I contrubuted yesterday and dowloaded the 5.x beta. (I assume I can just go back in in a few days and download the latest beta.).

One observation, after using it to calibrate a Tosh, 65HX93 RP-CRT. fed by a OPPO 971 Upconverting over DVI outputting 720P.

Most of the screens (not all of them) seem to "jiggle". It was rather distracting at first, but i finally got to where I could ignore it. I've used same DVD writer to burn other DVD's without issue, so I don't thikn it's a writer problem.

If you want, I can go though and see which screens are shaking. I can also check different outputs on the OPPO. If you want that info, let me know.

Rick

[CT_Wiebe]

rickie -- Go get the latest update, some of those problems should be fixed (if it's associated with the encoding of the files). Use the same name and password that you originally got (keep it in a safe place - you'll need it again too). I don't know if Scott has had a chance to update to the absolute latest "Instructions", but even the one that was on his site yesterday is still prettry good, but has a few errors (mostly spelling).

Anim -- See the calibration web site: www.calibtate.tv. You can also send him an email, see the address at the bottom of that page. Remember, if you're not familiar with display calibration, you need to do a lot more reading first (you can start with the documentation that is free, also on the site).

[rickie]

Originally Posted by CT_Wiebe

rickie -- Go get the latest update, some of those problems should be fixed (if it's associated with the encoding of the files). Use the same name and password that you originally got (keep it in a safe place - you'll need it again too). I don't know if Scott has had a chance to update to the absolute latest "Instructions", but even the one that was on his site yesterday is still prettry good, but has a few errors (mostly spelling).

Thanks, I'll probably wait a few days to get new docs at same time. I should have edited my post above, after I [osted it occurred to me to search the thread, and I see that the problem I mentioined was already identified.


Thanks,
Rick

[GetGray]

Originally Posted by rickie

Thanks, I'll probably wait a few days to get new docs at same time. I should have edited my post above, after I [osted it occurred to me to search the thread, and I see that the problem I mentioined was already identified.


Thanks,
Rick

Rick: See docs, Q&A section: "Can I use the Get Gray DVD to calibrate my CRT device?". (Answer is, it's not designed for CRT's). But FWIW, all of the patterns with the exceptions of Y/C delay, Frequencey Bursts, andthe rolling credits are created from an identical process. If some "jiggle" (on unsupported CRT) and some do not, I would be curious as to which do and don't.

Best,Scott

[mooney]

Claus.
Link is www.calibrate.tv

Just trying to help

[GetGray]

Originally Posted by mooney

Claus.
Link is www.calibrate.tv.com

Just trying to help

Thanks for the help, but...No, it's not. Website is www.calibrate.tv

"tv" is the TLD (top level domain) not "com" . I chose the tv TLD for obvious reasons, even though it's not what tv really stands for...

[GetGray]

Originally Posted by gregr

The reason the values 0 and 255 are prohibited isn't related to how a display would show the values. These values are prohibited because they are used to code timing information in the ITU-R BT.656 standard. The BT.656 standard defines a 4:2:2 YCbCr parallel (and serial) interface for transporting video data. One of its applications is to move digital video data between ICs in video products (for instance inside a DVD player between the output of an MPEG decoder and a video DAC or DVI transmitter). Therefore, if you include the values 0 or 255 in the YCbCr video information, it could confuse the sync timing of ICs that receive 4:2:2 YCbCr video using the BT.656 interface (shorten video lines, change the length of fields, etc.). So technically what is prohibited in Rec 601 is the use of the 8-bit values 0 and 255 in 4:2:2 YCbCr video, but since 4:4:4 YCbCr or 4:4:4 RGB values ultimately get converted to 4:2:2 YCbCr for BT.656 interfaces in video products, 0 and 255 must not be used in those formats either.

Oops, missed your reply. Thanks very much for the technical detail as to the whys. Version Beta 6.0 of the DVD now has no occurances of RGB 0/0/0 nor 255/255/255. 0/0/0 was already out, I had to step 255 to 254 in about 3 places which is done.

Thanks again, Scott

[GetGray]

OK guys, I think that will wrap it up, or close. Claus and I are on back and forth iteration #20 of the documentation and the current version is available on the website (again that's www.calibrate.tv). I've added the requested full-field patterns. I haven't left out much that was ever requested. I'll be going over the patterns one last time carefully and presuming nothing else is identified, version Beta 6.0 is a release candidate.

Time to look into PAL.

[maxleung]

You guys are awesome! I can't wait to try it out.

Maybe in a few months we can start talking about the H.264 AVC version?

[GetGray]

Originally Posted by maxleung

You guys are awesome! I can't wait to try it out.

Maybe in a few months we can start talking about the H.264 AVC version?

Don't laugh. I'm salivating over the encoder now. Only $499. I'll need a lot more contributors before doing it though

[CT_Wiebe]

There were only a few minor (cosmetic) errors in the documentation (#21), which have been corrected and sent to GetGray. The latest Video_TS files work smoothly too (on my laptop, I haven't had the chance to try it out on my HT system though).

Note to CRT users: You'll also need AVIA or DVE to set the maximum Contrast first, since these test patterns are not in the Caldisc as GetGray has stated (and documented in the "Instructions"). Since this disc is intended for fixed digital displays, there also may be some "flickering" on CRTs (analog display) as also stated above.

[gorman42]

Originally Posted by GetGray

Time to look into PAL.

Yes!!!

[mikea28]

Originally Posted by rickie

Ok, LOL, I contrubuted yesterday and dowloaded the 5.x beta. (I assume I can just go back in in a few days and download the latest beta.).

One observation, after using it to calibrate a Tosh, 65HX93 RP-CRT. fed by a OPPO 971 Upconverting over DVI outputting 720P.

Most of the screens (not all of them) seem to "jiggle". It was rather distracting at first, but i finally got to where I could ignore it. I've used same DVD writer to burn other DVD's without issue, so I don't thikn it's a writer problem.

If you want, I can go though and see which screens are shaking. I can also check different outputs on the OPPO. If you want that info, let me know.

Rick

You probably should try the 1080i output on your Oppo since your TV, being a CRT RPTV, is probably a 1080i native resolution set. This may or may not fix your jiggling problem, but it may make your image quality better since you won't be scaling twice.

[jvincent]

Originally Posted by GetGray

If some "jiggle" (on unsupported CRT) and some do not, I would be curious as to which do and don't.

As one of those who reported "jiggling", it's still there on Belle Nuit, Y/C delay, the colour ramps, colour bars, overscan, the colour windows (75% and 100%), the mix black/white bars in the br/cr section.

It's definitely not there in the frequency bursts.

Not sure what's going on, but this is a minor issue IMHO. One thing I did notice, which I think is an issue that needs to be fixed is the credits.

The grey background has equally spaced horizontal lines going through it. Very unprofessional looking.

It's only there on the credits chapter, and it's definitely in the pattern because I see it both on my display and when I'm VNC'd into the HTPC.

[Murray1080]

Just checking to see how far off are we for all the finals on our Getgray discs?
Do we get the final posted to us or do we burn our final?

many thanks I love using it!

[GetGray]

Well guys, it's been a long road getting to this announcement. Much longer than I originally expected. I guess that's the way projects go sometimes, especially one that's this popular. This is not a message to say the project is over, but one to announce it has reached a major milestone.

It's been educational and fun for the most part. The disc would not be where it is today without all the help and input from those here. It's taken about 4 1/2 months of picking away at it in all our spare time, but the result is what I think is a fine DVD indeed. All patterns have been scoured and checked, tested and triple checked. It has been tested and used by professionals and novices alike. It is already in use all over the world which is quite flattering for me. I've even made some friends in other countries from this project.

That said, this message is to announce that I am declaring the version Beta 6.1 as the first NTSC production release, GetGray Digital Video Calibration Version 1.0.

I would like to say a special thanks to Claus Wiebe who has worked with me extensively behind the scenes on the documentation. The final documentation draft version was #24. That's 24 revisions after I started "helping" with the documentation . I am proud of the finished documentation as well as the DVD. For those who followed along from the beginning, you know my original intent was to provide no docs other that some technical details in a text file. This is a far cry from that plan. Thanks to Claus's help and patience, together we have cobbled it into a professional piece of documentation. Claus continues to help me by helping others here on the thread. I don't have the resources to answer a lot of the questions, especially from new folks, but Claus has taken the time and has the patience to help. So again, a special thanks to Claus's participation. Maybe he'll be comfortable recommending his work now

I would also like to sincerely thank the experts here who have chimed in, especially:

Ron (dr_1394) for his outstanding input, programming, and behind the scenes assistance on the RGB to YCbCr details of which the disc would have been impossible without. We can thank Ron for having a DVD that is perfect in levels and color encoding.

Greg Rogers, extremely well known and highly respected in the AV community, who's input was timely, very welcome, and extremely valuable. To have someone of his caliber take time to contribute has been incredible.

Chris Wiggles whose original documentation works on Blacker than Black were my first learning experience on the subject a good long time ago.

Bob Sorel one of our resident AVS HTPC Forum Moderators, for giving me the impetus to go on and do the thing which I contemplated every time I switched calibration discs to get the pattern I wanted.

And to all the other folks I referred to early on as "big dogs" (a compliment ), as well as everyone who provided input and constructive criticism, thank you very much for the help as well.

The project is not complete yet. I like to think of it as a "living work" however this release makes it much less live . The next step is to deal with a PAL version. So any of you technical folks don't run away .

As for the future of the NTSC DVD, I remain open minded about it and will watch for opportunities to improve it with out complicating it, thus defeating it's original purpose. We'll keep an eye on the Ruby/DI issue and I might put something together for that purpose after dealing with PAL.

Now, for downloading the production version, please, don't everyone hit my server at once. If you don't need it right away, wait until you do, then download it to get your copy of the NTSC version 1.0 DVD. Note that the zip file contains BOTH the VIDEO_TS folder and the documentation pdf. You should burn them both to the DVD just as they exist in the zip file.

Everyone is required to read and agree to the License agreement and warnings before use. Page 1 of the document pdf.

See the first link of this thread for links to the patterns and documentation

next, on to PAL land..... the cycle begins again

Cheers,
Scott

[Murray1080]

The last disc I burned of getgray was 5.1, is there a 6.1 that I should be burning or am I missing something?

[GetGray]

No, 6.0 was the last Beta released to the public. Now we skip (back) to production version NTSC 1.0. It is uploading now. Be ready for everyone tomorrow. Moving credits take a lot of room. Disc is 70+Mb now.

[Murray1080]

Originally Posted by GetGray

No, 6.0 was the last Beta released to the public. Now we skip (back) to production version NTSC 1.0. It is uploading now. Be ready for everyone tomorrow. Moving credits take a lot of room. Disc is 70+Mb now.

I thought we we all to get notification to all the new versions? 6.0 is one I never got Im still on 5.1?

[Murray1080]

[quote=
Do we get the final posted to us or do we burn our final?

many thanks I love using it! [/QUOTE]

Any answer to this Q?