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Spears & Munsil HD Benchmark Blu-Ray 2nd Edition - Page 15

post #421 of 636
You aren't really "calibrating" when you use a PLUGE pattern to set the Brightness control and there is no way that any test/setup disc will help you get the right Contrast control. When you use a test/setup disc all you are doing is getting controls set reasonably well so that you can then REALLY calibrate the display with a meter (for measurements) and calibration software.

No test/setup disc will help you find the RIGHT Contrast setting. All a test/setup disc can to is reveal whether your TV clips white or not. And if it does clip white, you can learn what the HIGHEST Contrast setting is that can be used without clipping white. That HIGHEST setting is not necessarily the RIGHT setting for Contrast. In fact, most of the time, the highest Contrast setting you can use without clipping white is going to produce images that are TOO BRIGHT (unless you have the Backlight control turned way down - but backlight controls are their own problematic issue... you want the backlight set as low as possible so you get the darkest blacks, but that might make the light output of the backlight system get weird and you might have to use a higher setting to keep the lighting from negatively impacting the image, but you'd have to have a meter and calibration software to know if that was happening, otherwise you are just guessing).

The PLUGE pattern or digital steps pattern (0-25 or so) will let you get the Brightness control set correctly. Once that is done, you should NOT change the Brightness control. Turning it down more will remove shadow detail. Raising it will make black into a dark gray instead of black (or as close to black as your TV can get).
post #422 of 636
Trying to calibrate my Benq W1070 with the Spears and Munsil disc. But despite a midrange brightness setting, I'm finding the contrast pattern pretty useless, ie at both ends of the scale, and in the middle, I can see only a few of the off white numbered boxes I'm supposed to see, and none of the black squares inside the colored boxes.

As for brightness, nowhere on the spectrum can I get the left two vertical bars to show up, though I do see the right two vertical bars and can use the instructions to set brightness that way. I haven't tried to calibrate anything other than these two, because they seem like pretty crucial starting points before messing with anything else.

For what it's worth, I'm calibrating user 1 and 2, but with cinema mode specified, and in low-light output eco mode, projecting onto a Da-Lite Da-Mat high-contrast gray screen, sourced from a Panasonic DMP-BDT210 Bluray player (haven't tried to adjust anything on the player end). I found the out of the box image in cinema mode and eco lamp mode to be quite good with real-world content, my only major complaint would be pretty severe black crush, i.e. lack of detail in blacks, but I think that's a pretty common complaint with this projector, so I may only be able to minimize rather than eliminate that via calibration.

I must be making a newbie mistake with the contrast, but I'm at a loss. Help appreciated!
post #423 of 636
Quote:
Originally Posted by niccolo View Post

Trying to calibrate my Benq W1070 with the Spears and Munsil disc. But despite a midrange brightness setting, I'm finding the contrast pattern pretty useless, ie at both ends of the scale, and in the middle, I can see only a few of the off white numbered boxes I'm supposed to see, and none of the black squares inside the colored boxes.

As for brightness, nowhere on the spectrum can I get the left two vertical bars to show up, though I do see the right two vertical bars and can use the instructions to set brightness that way. I haven't tried to calibrate anything other than these two, because they seem like pretty crucial starting points before messing with anything else.

Your player or display (or receiver or processor) is clipping below and above the reference levels (16 and 235). This is bad, but it's not a disaster. You should still be able to get a reasonable picture, albeit with some amount of clipping at the high end, and perhaps some minor flatness in the deep shadow detail. Sometimes there is a mode switch that will get the player to stop the clipping. If you are using a receiver or video switcher that is clipping, bypassing it and going straight from the player to the display can fix this.

If you tell us the brand and model of player you're using, we can try to look up the manual and see if there's a likely setting. Or you can put up the PLUGE or Brightness pattern, turn the brightness on the display way up to ensure you'll see a change, and start toggling settings on the player and display to see if any of them will end the clipping.

If you can't get rid of the clipping, there is an alternative method for setting brightness detailed in the instructions: turn brightness down until the second bar from the left disappears, then up one notch, so it's just barely visible.

For contrast, the standard advice still works: try to make as many bars as possible appear. If that's only two or three bars, then that's the best you can do without getting different equipment that doesn't clip. Just move on to the rest of the adjustments.

You may find our expanded instructions handy, from our web site:

http://www.spearsandmunsil.com/portfolio/getting-started-with-the-high-definition-benchmark-2/

Hope all that helps! smile.gif
Edited by dmunsil - 12/13/13 at 3:35pm
post #424 of 636
Quote:
Originally Posted by dmunsil View Post

Your player or display (or receiver or processor) is clipping below and above the reference levels (16 and 235). This is bad, but it's not a disaster. You should still be able to get a reasonable picture, albeit with some amount of clipping at the high end, and perhaps some minor flatness in the deep shadow detail. Sometimes there is a mode switch that will get the player to stop the clipping. If you are using a receiver or video switcher that is clipping, bypassing it and going straight from the player to the display can fix this.

If you tell us the brand and model of player you're using, we can try to look up the manual and see if there's a likely setting. Or you can put up the PLUGE or Brightness pattern, turn the brightness on the display way up to ensure you'll see a change, and start toggling settings on the player and display to see if any of them will end the clipping.

If you can't get rid of the clipping, there is an alternative method for setting brightness detailed in the instructions: turn brightness down until the second bar from the left disappears, then up one notch, so it's just barely visible.

For contrast, the standard advice still works: try to make as many bars as possible appear. If that's only two or three bars, then that's the best you can do without getting different equipment that doesn't clip. Just move on to the rest of the adjustments.

You may find our expanded instructions with pictures handy, from our web site:

http://www.spearsandmunsil.com/portfolio/getting-started-with-the-high-definition-benchmark-2/

Hope all that helps! smile.gif

Appreciate the quick response! I tried to provide all the relevant equipment info in the post, but here it is again: Panasonic DMP-BDT210 Bluray player feeding Benq W1070 directly via HDMI, no pass through for now, projecting onto Da-Lite Da-Mat high-contrast gray screen, in a completely dark room with modest ambient light issues as a function of light-colored walls and ceiling.

I haven't made any adjustments at the Bluray player level (should I be?), just focusing on the projector for now. There, I've been calibrating user 1 and 2 modes, but with cinema mode specified, and in low-light output eco mode. Brightness has been 49-51, i.e. right in the middle, and as I mentioned, I set brightness using the alternative method specified in the instructions.

My experience seems to suggest that the contrast performance of my projector is atrocious. That seems odd; admittedly it's a budget projector, and it's definitely reported to have some black crush issues, consistent with my experience, but contrast is considered to be pretty decent on this projector. Right now the best I can do is to have about 3-4 bars visible, so apparently I'm clipping badly. Maybe this is my player rather than my projector's fault?
Edited by niccolo - 12/13/13 at 4:07pm
post #425 of 636
Quote:
Originally Posted by niccolo View Post

Appreciate the quick response! I tried to provide all the relevant equipment info in the post, but here it is again: Panasonic DMP-BDT210 Bluray player feeding Benq W1070 directly via HDMI, no pass through for now, projecting onto Da-Lite Da-Mat high-contrast gray screen, in a completely dark room with modest ambient light issues as a function of light-colored walls and ceiling.

Whoops! Sorry, I was reading too quickly and missed the player info. Yes, I believe that Panasonic clips by default. Change the Black Level setting in the player's Setup menu. I can't recall what their names are for the two settings but change it to whatever it's not set to now. That will (hopefully) stop the clipping.

As to whether you should change settings on the player, normally the answer is not at first. However, if your player is clipping, you do want to get that fixed first. We should probably have something about that in the "getting started" guide - I'll try to get that edited.

Keep in mind that clipping and the issues with the Contrast control have very little to do with actual measured contrast of the projector. "Contrast" is an overloaded word, referring to a measurement of the ratio between the brightest and darkest levels a projector can produce, and a picture control that allows you to set the overall gain on the luma channel (which by extension affects the other channels as well).
post #426 of 636
Quote:
Originally Posted by dmunsil View Post

Whoops! Sorry, I was reading too quickly and missed the player info. Yes, I believe that Panasonic clips by default. Change the Black Level setting in the player's Setup menu. I can't recall what their names are for the two settings but change it to whatever it's not set to now. That will (hopefully) stop the clipping.

As to whether you should change settings on the player, normally the answer is not at first. However, if your player is clipping, you do want to get that fixed first. We should probably have something about that in the "getting started" guide - I'll try to get that edited.

Keep in mind that clipping and the issues with the Contrast control have very little to do with actual measured contrast of the projector. "Contrast" is an overloaded word, referring to a measurement of the ratio between the brightest and darkest levels a projector can produce, and a picture control that allows you to set the overall gain on the luma channel (which by extension affects the other channels as well).

Great, I'll check that out when I get home. I was a bit dismayed my projector seemed to be clipping so badly, so glad it's probably just a setting on the player. And makes sense re clipping vs. contrast.

I'm assuming the link you sent is basically the same text as what's in the booklet with the disc, but let me know if not and I'll print that.

Really appreciate your help, the fact that both of you are on here, and responsive, makes me very happy that I purchased your disc over some alternatives.
post #427 of 636
Quote:
Originally Posted by niccolo View Post

I'm assuming the link you sent is basically the same text as what's in the booklet with the disc, but let me know if not and I'll print that.

The article on our web site is slightly expanded and edited. We made some adjustments after the booklet had gone to press. If it's convenient, I recommend the one on the web site.
post #428 of 636
Quote:
Originally Posted by niccolo View Post

Great, I'll check that out when I get home. I was a bit dismayed my projector seemed to be clipping so badly, so glad it's probably just a setting on the player. And makes sense re clipping vs. contrast.

I'm assuming the link you sent is basically the same text as what's in the booklet with the disc, but let me know if not and I'll print that.

Really appreciate your help, the fact that both of you are on here, and responsive, makes me very happy that I purchased your disc over some alternatives.

Sadly no luck so far, I'm still getting acute clipping. On the player, I have a Black Level Control with Lighter and Darker options, but contrast remains clipped either way. I can change HDMI Resolution from Auto to 1080p, and the image seems to change a little, but clipped contrast remains. I changed HDMI Color Mode to YCbCr 4:2:2 instead of 4:4:4, but doesn't seem to matter. Deep Color Output can be toggled on or off, but again makes no difference. I'm pretty sure my player is clipping, not my projector, but I'm stumped at this point.
post #429 of 636
Quote:
Originally Posted by niccolo View Post

Sadly no luck so far, I'm still getting acute clipping. On the player, I have a Black Level Control with Lighter and Darker options, but contrast remains clipped either way. I can change HDMI Resolution from Auto to 1080p, and the image seems to change a little, but clipped contrast remains. I changed HDMI Color Mode to YCbCr 4:2:2 instead of 4:4:4, but doesn't seem to matter. Deep Color Output can be toggled on or off, but again makes no difference. I'm pretty sure my player is clipping, not my projector, but I'm stumped at this point.

Well, that's frustrating.

Two possibilities:

- Your projector is clipping the inputs.
- Your player is clipping in both black level modes.

To be sure which it is, you'd have to connect the player to a display that you know doesn't clip, or connect a player that you know doesn't clip to your display. It could, of course, be that both are clipping. Or you can search for threads on AVS Forum about the player and projector and see if others have commented on clipping. You could certainly poke around in the display's menus and see if toggling any of the display settings affects clipping.

If you can't fix the clipping, and you don't feel like buying a new player or display, it's not the end of the world. You can still get a nice-looking picture. The effect of above-reference clipping is usually fairly subtle on most material. Occasionally it can be significant, but that's not the common case. And below-reference clipping is very subtle. Joe Kane has a demo he does that shows how below-reference clipping can be visible, but even then it's a fairly nuanced effect, and you have to find the right content to show it well. On most material it's effectively invisible. It makes it harder to set the Brightness control, and it kind of suggests the maker of the component that's clipping isn't paying attention to details. But it's not going to ruin the picture.
post #430 of 636
Quote:
Originally Posted by dmunsil View Post

Well, that's frustrating.

Two possibilities:

- Your projector is clipping the inputs.
- Your player is clipping in both black level modes.

To be sure which it is, you'd have to connect the player to a display that you know doesn't clip, or connect a player that you know doesn't clip to your display. It could, of course, be that both are clipping. Or you can search for threads on AVS Forum about the player and projector and see if others have commented on clipping. You could certainly poke around in the display's menus and see if toggling any of the display settings affects clipping.

If you can't fix the clipping, and you don't feel like buying a new player or display, it's not the end of the world. You can still get a nice-looking picture. The effect of above-reference clipping is usually fairly subtle on most material. Occasionally it can be significant, but that's not the common case. And below-reference clipping is very subtle. Joe Kane has a demo he does that shows how below-reference clipping can be visible, but even then it's a fairly nuanced effect, and you have to find the right content to show it well. On most material it's effectively invisible. It makes it harder to set the Brightness control, and it kind of suggests the maker of the component that's clipping isn't paying attention to details. But it's not going to ruin the picture.

The clipping seems very odd; both the Bluray player (Panasonic DMP-BDT210) and the projector (Benq W1070) are highly regarded and get great reviews from reputable reviewers like those at Projector Central. At this point I think I've toggled every setting, at both the player and projector ends, that seems like it might be clipping the high and low ends of the contrast spectrum. Unfortunately I don't have alternate Bluray players or display devices available for now to try to isolate which of these two is the culprit (and as you point out, it's not impossible both are).

My main complaint about my setup for now is black crush, i.e. loss of shadow detail, and I'm guessing this is both a function of the clipping and unlikely to be something I can do much about under the circumstances (setting black level to lighter on the player does seem to help a little with the black crush). I had hoped an amateur home calibration would let me improve this meaningfully. Instead I'm wondering whether I went with the wrong projector (and although I haven't seen any reports of clipping associated with the projector, there have been lots of reports of black crush, which is maybe the same thing?).

And with tint and color grayed out (I think this is common for digital HDMI connections to projectors), there's not much else, beyond Sharpness, for me to be tweaking in a basic amateur calibration. I've posted queries about whether the clipping is more widely observed in both the relevant player and projector threads, no responses so far.
Edited by niccolo - 12/14/13 at 9:32pm
post #431 of 636
Quote:
Originally Posted by niccolo View Post

The clipping seems very odd; both the Bluray player (Panasonic DMP-BDT210) and the projector (Benq W1070) are highly regarded and get great reviews from reputable reviewers like those at Projector Central. At this point I think I've toggled every setting, at both the player and projector ends, that seems like it might be clipping the high and low ends of the contrast spectrum. Unfortunately I don't have alternate Bluray players or display devices available for now to try to isolate which of these two is the culprit (and as you point out, it's not impossible both are).

My main complaint about my setup for now is black crush, i.e. loss of shadow detail, and I'm guessing this is both a function of the clipping and unlikely to be something I can do much about under the circumstances (setting black level to lighter on the player does seem to help a little with the black crush). I had hoped an amateur home calibration would let me improve this meaningfully. Instead I'm wondering whether I went with the wrong projector (and although I haven't seen any reports of clipping associated with the projector, there have been lots of reports of black crush, which is maybe the same thing?).

And with tint and color grayed out (I think this is common for digital HDMI connections to projectors), there's not much else, beyond Sharpness, for me to be tweaking in a basic amateur calibration. I've posted queries about whether the clipping is more widely observed in both the relevant player and projector threads, no responses so far.

Help me understand why clipping is tolerable, as you suggested and this does also: "The one area where the W1070 fell down was the Dynamic Range High test showing video levels above reference white (235) up to peak white (255). This test revealed that the W1070 was clipping all three primary colours and white, thus losing detail above video level 235. Whilst it would be nice to be able to see all the way up to peak white, because otherwise you might lose some detail in bright whites, it isn't a problem and certainly wouldn't adversely affect the projector's overall performance." http://www.avforums.com/review/benq-w1070-1080p-full-hd-3d-dlp-projector-review.493

Appreciated!
post #432 of 636
Quote:
Originally Posted by niccolo View Post

Help me understand why clipping is tolerable, as you suggested and this does also: "The one area where the W1070 fell down was the Dynamic Range High test showing video levels above reference white (235) up to peak white (255). This test revealed that the W1070 was clipping all three primary colours and white, thus losing detail above video level 235. Whilst it would be nice to be able to see all the way up to peak white, because otherwise you might lose some detail in bright whites, it isn't a problem and certainly wouldn't adversely affect the projector's overall performance." http://www.avforums.com/review/benq-w1070-1080p-full-hd-3d-dlp-projector-review.493

Appreciated!

Well, it's a controversial topic, and one with a ton of history and background I could go into. Most content is mastered so the bulk of the picture information is below 235. Some of it is even hard-clipped to attempt to keep everything below that point, because people misread the specs and think that's what they're supposed to do. In fact no broadcast video monitor (BVM) clips at 235, and the BVM is the gold standard of video. All movies and TV are mastered using BVMs. They all display information all the way up to 254 (because 255 is reserved as a signaling level used internally in studios). And while people are supposed to keep the important parts of the image in the range 16-235, in fact portions of the image stray above that level all the time. It's not usually highly visible, but if you're striving to get as close as possible to the BVM, then clipping is a no-no. You can actually demonstrate scenes in real movies that look different on a clipped display. Mostly the differences are quite subtle - things like flatness in clouds or steam, or color shifts in highlights and gleams on shiny objects. That's pretty minor in the grand scheme of things.

So we tell people to calibrate so the above-reference levels are visible, because that's how professional monitors are calibrated. But there are those who argue that you're dedicating a decent chunk of the brightest range of your display to levels that are really much less important to the image. We don't agree; most displays are plenty bright and contrasty enough that you still get a good picture with the above-reference range visible. We are joined in our opinion by many (but not all) of the top video experts in the industry.

In the computer industry, this all seems really odd, because monitors have a hard black at 0 and hard peak at 255, and there's none of this ambiguity. This is because computer displays evolved differently and have always been tied to digital imaging, while video has always had to stay compatible with analog standards. And so we're left with this distinction between reference level, which is 235, and peak level, which is 254. It's absolutely clear that levels up to 254 are intended to be visible. It's also clear that people mastering movies try very hard to keep the image levels mostly contained below 235.

So how important is it to display the above-reference range? It's entirely a judgment call. You can get a perfectly nice pleasing picture with clipped upper range. It's wrong, but it's rarely going to cause big picture problems that you'd notice.

Hope that helps you make up your mind.

Don
post #433 of 636
Assuming all aspects of your great Disc are complied with including clipping issues, how would my Display cope with the various Blu Rays and the different Gamma values that the mastering process them to.

In other words my Display may be calibrated perfectly but what confidence can I have that my choice of viewing media will match the calibration of my Display.
post #434 of 636
Quote:
Originally Posted by PE06MCG View Post

Assuming all aspects of your great Disc are complied with including clipping issues, how would my Display cope with the various Blu Rays and the different Gamma values that the mastering process them to.

In other words my Display may be calibrated perfectly but what confidence can I have that my choice of viewing media will match the calibration of my Display.

BVMs are generally calibrated to 2.4 gamma or very close, so there really isn't a huge range of gamma values. The idea of calibration is to get your monitor as close to a BVM as possible. You should have confidence that what you're seeing is as close as you can get to what the person who approved the transfer saw in the booth. And in fact different BVMs are actually all calibrated to be extremely close to each other. You can take a master tape from one post or mastering facility in Hollywood, take it across town to another house and it will look virtually identical. That's sort of central to the way home video mastering works. Many different companies will work on it over time, and they all are using calibrated monitors.
post #435 of 636
Quote:
Originally Posted by dmunsil View Post

Well, it's a controversial topic, and one with a ton of history and background I could go into. Most content is mastered so the bulk of the picture information is below 235. Some of it is even hard-clipped to attempt to keep everything below that point, because people misread the specs and think that's what they're supposed to do. In fact no broadcast video monitor (BVM) clips at 235, and the BVM is the gold standard of video. All movies and TV are mastered using BVMs. They all display information all the way up to 254 (because 255 is reserved as a signaling level used internally in studios). And while people are supposed to keep the important parts of the image in the range 16-235, in fact portions of the image stray above that level all the time. It's not usually highly visible, but if you're striving to get as close as possible to the BVM, then clipping is a no-no. You can actually demonstrate scenes in real movies that look different on a clipped display. Mostly the differences are quite subtle - things like flatness in clouds or steam, or color shifts in highlights and gleams on shiny objects. That's pretty minor in the grand scheme of things.

So we tell people to calibrate so the above-reference levels are visible, because that's how professional monitors are calibrated. But there are those who argue that you're dedicating a decent chunk of the brightest range of your display to levels that are really much less important to the image. We don't agree; most displays are plenty bright and contrasty enough that you still get a good picture with the above-reference range visible. We are joined in our opinion by many (but not all) of the top video experts in the industry.

In the computer industry, this all seems really odd, because monitors have a hard black at 0 and hard peak at 255, and there's none of this ambiguity. This is because computer displays evolved differently and have always been tied to digital imaging, while video has always had to stay compatible with analog standards. And so we're left with this distinction between reference level, which is 235, and peak level, which is 254. It's absolutely clear that levels up to 254 are intended to be visible. It's also clear that people mastering movies try very hard to keep the image levels mostly contained below 235.

So how important is it to display the above-reference range? It's entirely a judgment call. You can get a perfectly nice pleasing picture with clipped upper range. It's wrong, but it's rarely going to cause big picture problems that you'd notice.

Hope that helps you make up your mind.

Don

Thank you for taking the time to share this information, this is exceptionally helpful!

If I understand correctly, while clipping above reference white (235) entails a modest loss of detail as described in your post, clipping below reference black (16) does not entail a similar loss of detail (since 16 is already the blackest black), so the only thing non-clipping enables at the low end is a slightly more precise identification of the threshold based on which brightness should be set.
post #436 of 636
Quote:
Originally Posted by dmunsil View Post

BVMs are generally calibrated to 2.4 gamma or very close, so there really isn't a huge range of gamma values. The idea of calibration is to get your monitor as close to a BVM as possible. You should have confidence that what you're seeing is as close as you can get to what the person who approved the transfer saw in the booth. And in fact different BVMs are actually all calibrated to be extremely close to each other. You can take a master tape from one post or mastering facility in Hollywood, take it across town to another house and it will look virtually identical. That's sort of central to the way home video mastering works. Many different companies will work on it over time, and they all are using calibrated monitors.

Have things changed recently then?

Certainly your reply has not been the case causing many to despair at the almost cavalier approach to standerdisation by the mastering studios.

I notice you say ''generally'', why is this not a mandatory figure bearing in mind the patient attention to detail your disc displays?
post #437 of 636
Quote:
Originally Posted by niccolo View Post

Thank you for taking the time to share this information, this is exceptionally helpful!

If I understand correctly, while clipping above reference white (235) entails a modest loss of detail as described in your post, clipping below reference black (16) does not entail a similar loss of detail (since 16 is already the blackest black), so the only thing non-clipping enables at the low end is a slightly more precise identification of the threshold based on which brightness should be set.

As I mentioned earlier, Joe Kane has demoed visible effects in real-world material caused by below-reference clipping. To some extent it depends on where the clipping happens. If it's clipping in RGB (i.e. post-color-conversion), then that's not so bad. We don't like it, but its effect on the image is minimal. If the clipping is on the Luma or Cb or Cr channels before the RGB conversion, that can potentially be quite visible. We have built a pattern that shows a pretty stark difference between clipped Y and unclipped Y, and it's visible on a properly calibrated display. People forget that when Y dips below 16, that doesn't mean all three RGB channels are also below 16. So you can get faint shadow detail that's missing in very dark areas of the screen.
post #438 of 636
Quote:
Originally Posted by PE06MCG View Post

Have things changed recently then?

Certainly your reply has not been the case causing many to despair at the almost cavalier approach to standerdisation by the mastering studios.

I notice you say ''generally'', why is this not a mandatory figure bearing in mind the patient attention to detail your disc displays?

In the professional mastering world in Hollywood, everyone has been using the same gamma pretty much forever. Movies from the big studios are generally mastered on calibrated BVMs and always have been. There have been isolated examples of films that got messed up somewhere else in the disc mastering process, but those are not common.

I say "generally" because there's a lot of content out there and some mastering is done by random people in their basement on their computer. Do they have a BVM? Probably not. But since there's no way to know what their monitor looks like it's just not possible to match their display. If they're using a calibrated display then what you see will match what they see. If not, then it's just pot luck - you get what you get.

So recent Disney, Universal, Warner Bros, etc. - they'll all be done on a calibrated BVM. Random titles from random little companies - who knows? But you can't worry about that. Calibrate for the best content, and let the not-best content be whatever it is.
post #439 of 636
Quote:
Originally Posted by dmunsil View Post

In the professional mastering world in Hollywood, everyone has been using the same gamma pretty much forever. Movies from the big studios are generally mastered on calibrated BVMs and always have been. There have been isolated examples of films that got messed up somewhere else in the disc mastering process, but those are not common.

I say "generally" because there's a lot of content out there and some mastering is done by random people in their basement on their computer. Do they have a BVM? Probably not. But since there's no way to know what their monitor looks like it's just not possible to match their display. If they're using a calibrated display then what you see will match what they see. If not, then it's just pot luck - you get what you get.

So recent Disney, Universal, Warner Bros, etc. - they'll all be done on a calibrated BVM. Random titles from random little companies - who knows? But you can't worry about that. Calibrate for the best content, and let the not-best content be whatever it is.

I found this on the internet which alarmed me.
Perhaps you could comment on the different view it suggests:

http://forums.creativecow.net/thread/286/157

Chris Wiggles post half way down the page suggests that standerdisation is far from the case.
post #440 of 636
Quote:
Originally Posted by PE06MCG View Post

I found this on the internet which alarmed me.
Perhaps you could comment on the different view it suggests:

http://forums.creativecow.net/thread/286/157

Chris Wiggles post half way down the page suggests that standerdisation is far from the case.

Chris is right, but I think his concerns are with people somewhat outside the mastering world. CreativeCow is a forum for digital filmmakers, and they're arguing about how you should configure your editing bays and so forth. I personally think if your target is home video displays, you're foolish if you don't target approximately 2.4, but people get weird about gamma and I can't figure out why. The people on that thread that say that the monitors should be 2.2 for US are just wrong. No CRT ever had 2.2 gamma. Some existing displays have 2.2 (or some other) gamma when they ship from the factory, and for that reason (and others) they don't look like a BVM. But that's just another aspect of the whole "display manufacturers want their displays to look good at the Best Buy" issue. Lower gamma values look brighter, which makes displays stand out.

The original BVMs didn't really have adjustable gamma; they were CRTs and you got the gamma that you got. That gamma was approximately 2.4 by most measurements.

People doing special effects work and some other types of graphics work outside the video mastering world will use gammas that are kind of all over the map, and this causes some amount of consternation and difficulty, but not as much as you'd think. If an effects technician is doing compositing on a 2.2 gamma monitor, he or she is just seeing an extra bright image. They don't do the final color timing of the video. The final color timing is done on a BVM.

There have been some problems with some post or mastering houses that have been moving from CRT-based BVMs to newer flat panels and have gotten it into their heads that they should follow sRGB or BT.709 for the monitor gamma, and this is wrong. But slowly they're getting the picture, so to speak.

I don't want to downplay the problem of lack of knowledge of correct gamma standards for monitors. It's a real problem, but less so for home video enthusiasts than for the video and film industry. It's an "inside baseball" problem for the most part where, for example, the monitors that filmmakers watch dailies on might not be calibrated to the same standard as the mastering house, and that's sort of a problem but not much of one, because dailies never look like the finished product anyway. Home video mastering has been done on 2.4 gamma monitors, and mostly continues to be done on 2.4 gamma monitors, plus or minus about 0.05, which is trivial.

Mastering for digital cinema, on the other hand, is done on monitors calibrated for digital cinema. That has a different gamma. But the encoding gets readjusted when it's converted to home video, so the home video product matches the final look of the cinema product.
post #441 of 636
Thanks for the excellent post Don!

Now that BT1886 is making its way into the industry (or so I hear it is), things should be much better. Not only will the 2.4 exponent on the display end be explicitly defined, but the changes in luminance across the grayscale should be more perceptually uniform across a wider range of displays with differing black levels.

I hope this isn't too off topic, but what are your thoughts on the SMTPE-C primaries still being used after Rec 709 was introduced (while CRTs were still mainstream).
post #442 of 636
Quote:
Originally Posted by dmunsil View Post

As I mentioned earlier, Joe Kane has demoed visible effects in real-world material caused by below-reference clipping. To some extent it depends on where the clipping happens. If it's clipping in RGB (i.e. post-color-conversion), then that's not so bad. We don't like it, but its effect on the image is minimal. If the clipping is on the Luma or Cb or Cr channels before the RGB conversion, that can potentially be quite visible. We have built a pattern that shows a pretty stark difference between clipped Y and unclipped Y, and it's visible on a properly calibrated display. People forget that when Y dips below 16, that doesn't mean all three RGB channels are also below 16. So you can get faint shadow detail that's missing in very dark areas of the screen.

Got it. Thanks again for taking the time to patiently explain this stuff to a relative newbie.
post #443 of 636
Quote:
Originally Posted by dmunsil View Post

People doing special effects work and some other types of graphics work outside the video mastering world will use gammas that are kind of all over the map, and this causes some amount of consternation and difficulty, but not as much as you'd think. If an effects technician is doing compositing on a 2.2 gamma monitor, he or she is just seeing an extra bright image. They don't do the final color timing of the video. The final color timing is done on a BVM.

Then I'm curious why the calibration software on computers are recommending 2.2 as default. I've only had experience with Datacolor and X-Rite as they're recommending 2.2.
post #444 of 636
Quote:
Originally Posted by xvfx View Post

Then I'm curious why the calibration software on computers are recommending 2.2 as default. I've only had experience with Datacolor and X-Rite as they're recommending 2.2.

Because that's the calibration standard for computer graphics. Well, the calibration standard is a multi-part curve, but it's intended to be close to 2.2. Video standards are not the same as computer standards.
post #445 of 636
I want to ask this in Joe 6 Pack terms. Is 2.4 brighter or darker than 2.2? My Sammy has gamma settings from -3 to +3 with -3 making the entire picture darker and +3 makes it brighter and 0 is default. I'm having a heck of a time finding any setting that looks like 2.4

I thought -2 was close, but after looking again, I think 0 (brighter) is closer, but I'm not sure anymore. Any helpful hints other than what is on the disc?
post #446 of 636
the higher the exponent, the darker the image, especially below 50% gray. But a higher exponent will "accelerate" to white at a higher rate, above 50% gray.

(I think I've got that right).
post #447 of 636
lol So 2.4 is darker than 2.2?
post #448 of 636
agreed.
post #449 of 636
@ dmunsil

Hi Don,

Many thanks for your informative reply (see your post #440).

Particularly in reply to that post may I paste the part of Chris Wiggles post that I think relates to the end user the 'Consumer'' as he puts it:

You are right, EBU thankfully does explicitly define display gamma of 2.35. Forgot about that one.

I thoroughly agree with Poynton here about the need to define display gamma, because there are MANY people who think that 2.2 is reference gamma and sadly it has sort of just become a de-facto reference for a lot of people for absolutely no good reason except that there is no explicit standard and people are confused. And quite a few of them appear to think that 2.2 is defined somewhere as a display gamma, when that is not the case (except for sRGB which is not a video standard). So what mastering houses are doing is all over the map. This leaves consumers unable to calibrate to a single gamma, because you don't know if something was mastered at say 2.2, or 2.35, or 2.5, or 2.6, or what. And the difference between 2.2 and 2.6 is HUGE. We can quibble about slight gamma issues, but once you're talking about the ranges of gammas I hear people talking about calibrating to, you quickly realize that everyone is just flying by the seat of their pants and just making up whatever value they want because "it looks good to me." And that's not a way to run a professional technical field... frown.gif


http://www.poynton.com/notes/PU-PR-IS/Poynton-PU-PR-IS.pdf


Regards,
Chris


Surely this part has little to do with film making and everything to do with the mastering process that gives us our Blu Rays etc..

I am amazed that the Film Makers do not standardise the output gamma at this final stage if only to give some credibility to their wishes that the Fidelity of the original 'Art' is maintained.

I agree that we can only concentrate on making our calibrations accurate (with the help of your excellent disc of course), but that nagging doubt about the gamma of the Blu Ray remains.

Obviously things may have changed since Chris's post on CC but you did say that you agree with Chris in your post?
Perhaps I have misread this part of his post?

Edit:
Sorry, I forgot to mention your comment about the need to calibrate to a gamma value of 2.4.
This is not only good advice for the reasons you outline but it also narrows down the potential gamma value difference that a media source may have (Chris suggests 2.2 to 2.6 as possibilities)..
A nice intermediate value between the potential extremes of any source.

Peter
Edited by PE06MCG - 12/17/13 at 1:32am
post #450 of 636
PE06, please read the replies carefully. A number of people in a number of different threads have patiently answered the same question repeatedly. Everything you are asking is answered in Don's post
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