HOW-TO: Calibrating Display to Match HTPC Output - Page 13 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #361 of 486 Old 01-21-2007, 01:54 AM
AVS Special Member
 
maxleung's Avatar
 
Join Date: Mar 2003
Location: Calgary, Alberta, Canada
Posts: 3,495
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
mark, I just picked up a new LCD monitor for myself, and am discovering the problem of most LCD PC monitors having no options for video levels.

For example, my NEC 20 WMGX2 (the best LCD monitor I've ever seen, BTW) has brightness and contrast adjustments - but they don't behave quite the way I expected. Adjusting brightness appears to affect backlight strength along with black level, and same for contrast, except it favors the white level end. However, no combination of these settings can make level 16 with level 0 (true black).

For HTPC use, I have found a good workaround - if you use VMR you can adjust the player brightness controls (for example, in Zoomplayer or TheaterTek, which both support ProcAmp controls). Adjusting brightness in the negative range will do a linear level shift in that direction. For example, a brightness setting of -4 will reduce ALL levels in the image by 4, clipping levels of 4 and less to 0, IF contrast is kept at 0. If you increase contrast as well, then a level expansion is performed (and can cause clipped highlights - but if you don't go too far shouldn't be noticeable).

You'll have to experiment - on my LCD monitor I'm using a VMR9 brightness of -4 and kept VMR9 contrast at 0 to prevent level expansion and prevent contouring. Unfortunately, this does mean bright scenes are not as bright as they could be - which is why I did not try a brightness of -16 to clamp level 16 to 0 - the whole picture would be too dim unless I upped the contrast.
maxleung is offline  
Sponsored Links
Advertisement
 
post #362 of 486 Old 01-21-2007, 02:16 AM
AVS Special Member
 
maxleung's Avatar
 
Join Date: Mar 2003
Location: Calgary, Alberta, Canada
Posts: 3,495
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
More on calibrating my NEC 20WMGX2 for movie watching:

This monitor, like most LCDs, have a 2.2 gamma. This can be quite annoying because it appears most DVDs are mastered with 2.5 gamma in mind. This has the effect of uncovering large amounts of shadow detail and film grain - but with the unfortunate side-effect of also uncovering lots of mosquito noise and macroblocking inherent in video compression! Ouch!
maxleung is offline  
post #363 of 486 Old 01-21-2007, 09:46 AM
Senior Member
 
Charles Black's Avatar
 
Join Date: Sep 2003
Location: Lopez Island, Washington
Posts: 340
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I just increase the end to end gamma by .3 or so in ffdshow to get this under control. The ffdshow gamma control works OK, at least for small gamma adjustments. I have done the same thing with Powerstrip in the past and it worked too.
Charles Black is offline  
post #364 of 486 Old 02-21-2007, 11:02 PM
Member
 
Acrimony's Avatar
 
Join Date: Jul 2004
Posts: 27
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Do PCs represent black at 0 IRE or 7.5 IRE, or is it even relevant when discussing HTPCs?
Acrimony is offline  
post #365 of 486 Old 02-21-2007, 11:22 PM
 
ChrisWiggles's Avatar
 
Join Date: Nov 2002
Location: Seattle
Posts: 20,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Acrimony View Post

Do PCs represent black at 0 IRE or 7.5 IRE, or is it even relevant when discussing HTPCs?

It's not really relevant. Best just to deal with analog PC outputs in mV.

PS: this is discussed in the guide in my signature, which also references this thread which discusses this in further detail:

http://archive.avsforum.com/avs-vb/s...61#post4030461
ChrisWiggles is offline  
post #366 of 486 Old 02-22-2007, 04:44 AM
 
tbrunet's Avatar
 
Join Date: Jul 2005
Location: Savannah, GA
Posts: 2,750
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by maxleung View Post

This can be quite annoying because it appears most DVDs are mastered with 2.5 gamma in mind.

Color correction and encoding CRT reference monitors (Sony, Ikegami, ect) are designed to have a ruler straight (OETF) power transfer function of 2.20 all the way down to 1% of reference white.

Gamma itself is subjective, and definitely interacts with viewing ambient. The OETF(optical/electric transfer function) for most if not all consumer displays is so far from the theoretical inverse of the encoding function (2.20) it's totally irrelevant.
tbrunet is offline  
post #367 of 486 Old 03-01-2007, 08:43 AM
AVS Special Member
 
Ozy666's Avatar
 
Join Date: Jul 2003
Posts: 2,158
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by ChrisWiggles View Post

I vehemently agree with stranger89.

There are some that disagree with this and like to scope the PC and change it around, but I recommend against that.

As long as:
1) your PC is outputting the video correctly without clipping, etc, leave brightness/contrast controls be in the PC video card
2) your display has sufficient adjustment range to accomodate the PC's output correctly

Also, make sure you are using VIDEO level patterns from say Avia/DVE/getgray disc etc.

There are a lot of PC calibration patterns out on the net and almost 100% of them are for GRAPHICS levels, not video.

A question for you and/or stanger:

How would one calibrate the software/video card/display if one wanted to display both video and also PC material (games, etc...) properly?

It seems that one must be able to display both (0-255) and (16-235) and easily switch between the two. In this case, wouldn't it make sense to set the display and video card for 0-255 and use the video software to calibrate to 16-235?

Ozy
Ozy666 is offline  
post #368 of 486 Old 03-01-2007, 09:38 AM
AVS Addicted Member
 
stanger89's Avatar
 
Join Date: Nov 2002
Location: Marion, IA
Posts: 17,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 71 Post(s)
Liked: 120
I don't, I pick which one is more important (Video on my HTPC) and sacrifice the other.

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
stanger89 is offline  
post #369 of 486 Old 03-01-2007, 09:51 AM
 
ChrisWiggles's Avatar
 
Join Date: Nov 2002
Location: Seattle
Posts: 20,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by stanger89 View Post

I don't, I pick which one is more important (Video on my HTPC) and sacrifice the other.

I do the same.

If you do critical work, I would have two calibrations at the displa and switch between them. I do almost exclusively video on my HTPC as it's dedicated, basically only the GUI is the only thing I see that isn't video levels so it's not a big deal.
ChrisWiggles is offline  
post #370 of 486 Old 03-01-2007, 01:44 PM
AVS Special Member
 
maxleung's Avatar
 
Join Date: Mar 2003
Location: Calgary, Alberta, Canada
Posts: 3,495
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
If you really want to do both you could probably do it using GretagMacbeth's Calibration Tester tool. It can create and use text files that remap the videocard's lookup tables.

So, you could remap the 16-235 range to 0-255 (crushing potential highlights and clipping BTB) or if you want to preserve highlights, you could expand 16-255 to 0-255, clipping only BTB. You could even remap 16-255 down to 0-235, preserving highlights but making a huge sacrifice in brightness. The videocard's LUTs are your oyster.

The advantage to this is that you won't need to fiddle with display presets, or deal with a display that cannot be calibrated for video levels. You also have more precise control over how much banding you wish to tolerate.

I believe Powerstrip also has LUT control options - which could be assigned to a hotkey, but I haven't tried this feature yet.
maxleung is offline  
post #371 of 486 Old 03-01-2007, 04:45 PM
AVS Special Member
 
JKohn's Avatar
 
Join Date: Jan 2001
Location: Houston, TX
Posts: 2,948
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The downside to making signficant changes to the LUT is that it's a pretty blunt tool and you're likely to introduce banding and posterization if you make those kinds of changes. IMHO it's a shame the concept of video levels carried over to HD/ATSC. There's just no reason to have black at RGB=16, this is a holdover from the analog days.
JKohn is offline  
post #372 of 486 Old 03-01-2007, 06:36 PM
AVS Special Member
 
dlarsen's Avatar
 
Join Date: Mar 2001
Location: Beaverton, OR, USA
Posts: 1,908
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by JKohn View Post

IMHO it's a shame the concept of video levels carried over to HD/ATSC.

Interesting comment JKohn. We were just discussing this VERY subject in this thread over HERE. You might find it interesting

Dave
dlarsen is offline  
post #373 of 486 Old 03-01-2007, 07:18 PM
AVS Special Member
 
maxleung's Avatar
 
Join Date: Mar 2003
Location: Calgary, Alberta, Canada
Posts: 3,495
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
JKohn, I already outlined how you can avoid banding and posterization - just do the shift without any expansions. And you can shift only a little bit - instead of going from 16-255 down to 0-235, you can try going to 12-251. I've done that myself on my LCD display - it works well, because the difference between level 0 and level 12 is very small when you eyeball it.

But if you have a well-designed display (ie. 10 bit internal processing, "understands" video levels, etc.) then you are okay.
maxleung is offline  
post #374 of 486 Old 03-01-2007, 09:26 PM
AVS Special Member
 
JKohn's Avatar
 
Join Date: Jan 2001
Location: Houston, TX
Posts: 2,948
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
JKohn, I already outlined how you can avoid banding and posterization - just do the shift without any expansions. And you can shift only a little bit - instead of going from 16-255 down to 0-235, you can try going to 12-251. I've done that myself on my LCD display - it works well, because the difference between level 0 and level 12 is very small when you eyeball it.

Where are you suggesting this shift take place? Desktop color settings? Display settings? Neither would solve the original problem because they would also affect non-video sources. The only way I can see that working is if it were supported in the video playback software.

The problem is, there's no way to calibrate for both video and PC levels. If you calibrate for video levels everything else on your PC will be wrong. And there's just no good reason for this whole mess, studio levels are an anachronism with no reason to exist in digital video.
JKohn is offline  
post #375 of 486 Old 03-01-2007, 10:13 PM
AVS Special Member
 
dlarsen's Avatar
 
Join Date: Mar 2001
Location: Beaverton, OR, USA
Posts: 1,908
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
The only sensible solution I can see (if one subscribes to the notion that rendering video at sRGB levels is filled with nasty dragons and must be avoided- I certainly don't) would be to render StudioRGB levels to the overlay. And no- overlay does not automatically mean sRGB levels as is a common misconception. It has independent gain and offset controls (B/C). That's the difference between StudioRGB and sRGB. Gain and Offset.

Now if you subscribe to the notion that you shouldn't render to overlay, or EVER adjust a source, because again- that's filled with dragons and must be avoided, then I guess you are in a pickle and must do what Chris and Stanger do.

I recall Don and Stacy (when they were associated with MS) commenting about how LongHorn (the successor to XP) was going handle this whole issue between StudioRGB and sRGB. The OS was going to determine if one was viewing video' or graphics' and dynamically change levels on the fly. Remember that? What happened to that? I've seen no mention of this feature' making it's way into Vista. Musta gotten dropped? Why? Perhaps it turns out to be harder than it first seemed to make the distinction in the land of convergence. Perhaps the cure turned out much worse than the purported disease (or that it was made out to be a disease because MS had the cure' with what was to become MCE and PCs were broken' for video without MCE because of their sRGB levels)

I can suggest that perhaps one try rendering video to a properly calibrated sRGB environment and see for themselves if there are dragons there.

Dave
dlarsen is offline  
post #376 of 486 Old 03-01-2007, 10:32 PM
 
ChrisWiggles's Avatar
 
Join Date: Nov 2002
Location: Seattle
Posts: 20,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
I can suggest that perhaps one try rendering video to a properly calibrated sRGB environment and see for themselves if there are dragons there.

Many people do this. Guess what? You get banding unless you have a high-bitdepth pipeline all the way through to the display. You also get clipping, but you don't care about clipping as you have clearly said in the past. If we assume that one does have a high-bitdepth processing and transmission pipeline all the way through the display AND that we don't care about clipping, then there should be no degradation.
ChrisWiggles is offline  
post #377 of 486 Old 03-01-2007, 11:18 PM
Senior Member
 
Charles Black's Avatar
 
Join Date: Sep 2003
Location: Lopez Island, Washington
Posts: 340
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Ozy

Ffdshow is a good way to have an HTPC expand the 16 to 235 studio video levels to levels 0 to 255 which is correct for a PC monitor. As an added bonus it will also pixel double as well so that there is a lot less pixelization with DVDs. I would try that first if your HTPC is up to it since you may not notice any banding (I never see any banding!) and certainly no posterization. Ffdshow is a good place to do minor gamma adjustments too and can handle the RGB gammas individually. Many also use it to do some sharpening and de-interlacing. My main issues have been occasional short freezes of the image with computer O/S activity mainly related to hard to read disks and the XP file indexing service. If you HTPC is too slow stuttering can be a problem. Zoom player supports ffdshow and there are others as well. I have also calibrated my E8500 to studio video levels with equally satisfactory results but the level 255 internal setup screens and PC screens are in danger of burning the phosphor if the white reference is set to level 235. I use a Spyder2 Pro to make a profile that goes into the video card LUT giving a nearly perfect gray-scale calibration. If the CRTs are adjusted correctly the profile has little to do and is just barely noticable when clicking it on and off quickly. Some uses of the Spyder2 Pro have wanted the video to be not quite as warm looking. That is a matter of taste and is not really a problem anyway since Precal and Optical can be set to any temperature.

Charlie
Charles Black is offline  
post #378 of 486 Old 03-01-2007, 11:46 PM
Senior Member
 
Charles Black's Avatar
 
Join Date: Sep 2003
Location: Lopez Island, Washington
Posts: 340
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Dave,

I suppose MS found out that about the best a PC can do is to expand the studio video to 0 to 255!

Now the monitor is a different story. My son bought a $700 Visio (about 30") flat screen TV/monitor at Costco and it seems to do both jobs tolerably well. It uses the small HDMI connector for studio video and a larger PC style one for the PC as well as some other connection options. I don't imagine that it is stable enough for a serious calibration but who knows! Large viewing angles are OK and the screen ambient reflection is very low. Colors are "American Candy" if wanted and it's BRIGHT.

Charlie
Charles Black is offline  
post #379 of 486 Old 03-02-2007, 12:59 AM
AVS Special Member
 
dlarsen's Avatar
 
Join Date: Mar 2001
Location: Beaverton, OR, USA
Posts: 1,908
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Charles Black View Post

I suppose MS found out that about the best a PC can do is to expand the studio video to 0 to 255!

It sure seems like it's got folk like Nvida confused. They seem to toggle back and forth with every other driver release. Kinda like the SetTop HD-DVD players and game consoles, some go one way, some go the other. They can't decide if they are a computer or video appliance. Convergence is a mess and a BTB/WTW/banding myth is at the heart of it. Kinda tragic in a way. I'm like you, doing all rendering at sRGB levels in harmony with all other things PC and enjoying a ruler-flat gray-scale, great colorimetery, banding free image via custom LUTS and not a hint of non-source crushing- all at sRGB levels and have been for years. Like I said, I never saw those emperors new clothes that everyone's been raving about.

Dave
dlarsen is offline  
post #380 of 486 Old 03-02-2007, 01:15 AM
AVS Special Member
 
dlarsen's Avatar
 
Join Date: Mar 2001
Location: Beaverton, OR, USA
Posts: 1,908
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by ChrisWiggles View Post

Many people do this. Guess what? You get banding

More nasty dragons eh? Do you have a picture of these dragons you can show us? Can you tell us more specifically where and when you see these dragons?

Dave
dlarsen is offline  
post #381 of 486 Old 03-02-2007, 06:15 AM
AVS Addicted Member
 
stanger89's Avatar
 
Join Date: Nov 2002
Location: Marion, IA
Posts: 17,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 71 Post(s)
Liked: 120
Quote:
Originally Posted by ChrisWiggles View Post

Many people do this. Guess what? You get banding...

Just ignore him or this thread will shortly degenerate and be closed (I think the last few were).

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
stanger89 is offline  
post #382 of 486 Old 03-02-2007, 06:45 AM
AVS Special Member
 
JKohn's Avatar
 
Join Date: Jan 2001
Location: Houston, TX
Posts: 2,948
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:


The only sensible solution I can see (if one subscribes to the notion that rendering video at sRGB levels is filled with nasty dragons and must be avoided- I certainly don't) would be to render StudioRGB levels to the overlay. And no- overlay does not automatically mean sRGB levels as is a common misconception. It has independent gain and offset controls (B/C). That's the difference between StudioRGB and sRGB. Gain and Offset.

So how do the Brightness and Contrast controls affect the levels expansion that Overlay does?

Right now I do have my HTPC calibrated to PC levels. When I originally set this machine up I had trouble getting 1080i HD to playback reliably with VMR9, so using Overlay was the answer. But while the levels expansion does make calibration easier, it also does cause some occasional banding.
JKohn is offline  
post #383 of 486 Old 03-02-2007, 07:27 AM
AVS Special Member
 
Ozy666's Avatar
 
Join Date: Jul 2003
Posts: 2,158
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Charles Black View Post

Ozy

Ffdshow is a good way to have an HTPC expand the 16 to 235 studio video levels to levels 0 to 255 which is correct for a PC monitor. As an added bonus it will also pixel double as well so that there is a lot less pixelization with DVDs. I would try that first if your HTPC is up to it since you may not notice any banding (I never see any banding!) and certainly no posterization.
Charlie

I can certainly give that a try for DVDs and similar SD media. However, I was hoping for a solution to HD playback in PowerDVD as well. Perhaps, as a previous poster suggested, if I set up different profiles for the display driver which I can switch on the fly.

I'll probably have to tinker a bit to find an acceptable/optimal solution.

Ozy
Ozy666 is offline  
post #384 of 486 Old 03-02-2007, 08:33 AM
AVS Special Member
 
maxleung's Avatar
 
Join Date: Mar 2003
Location: Calgary, Alberta, Canada
Posts: 3,495
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
Quote:


Where are you suggesting this shift take place? Desktop color settings? Display settings? Neither would solve the original problem because they would also affect non-video sources. The only way I can see that working is if it were supported in the video playback software.

JKohn, I failed to mention one solution that works for me without losing PC levels for the desktop - use VMR9 procamp controls!

I leave my LCD monitor calibrated for sRGB (PC levels), and then in Zoomplayer and TheaterTek, I choose VMR9 for the video renderer. The default brightness is set to zero - but for my LCD I use -4. This lowers the 16-255 range to 12-251. Banding is impossible as long as I leave contrast at the default setting of 1.

So when I watch video on my LCD, I don't worry about messing up my desktop calibration.

My original suggestion used GretagMacbeth's Calibration Tester tool, which reads and modifies the videocard's LUTs. It overrides all player settings. Presumably it will affect overlay as well, but I haven't tested it. I despise Overlay anyways.
maxleung is offline  
post #385 of 486 Old 03-02-2007, 09:25 AM
AVS Special Member
 
JKohn's Avatar
 
Join Date: Jan 2001
Location: Houston, TX
Posts: 2,948
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:


I leave my LCD monitor calibrated for sRGB (PC levels), and then in Zoomplayer and TheaterTek, I choose VMR9 for the video renderer. The default brightness is set to zero - but for my LCD I use -4. This lowers the 16-255 range to 12-251. Banding is impossible as long as I leave contrast at the default setting of 1.

Have you done a screen-cap of something like a stepped grayscale to verify that all it does is shift the entire range downwared? Even so, having black at 12 instead of 16 might be an improvement but you're still not going to be getting the blackest blacks you can for video material if your display really is calibrated for PC levels. And on the other end, you've moved nominal white from 235 (not 255) to 231. I would think the end result of this adjustment would significantly compromise black levels and overall contrast ratio.
JKohn is offline  
post #386 of 486 Old 03-02-2007, 09:33 AM
AVS Special Member
 
maxleung's Avatar
 
Join Date: Mar 2003
Location: Calgary, Alberta, Canada
Posts: 3,495
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
JKohn, yes, I tested with a grayscale pattern from the DVE DVD disc and with 3no's levels patterns.

My LCD monitor is quite bright - around 130 cd/m^2, so moving nominal white wasn't a big deal. If I went lower than a brightness of -4 then yes, it would be too dim and I would also crush black detail.

The monitor's gamma is 2.2 as well - so I still get plenty of shadow detail with a lowered VMR9 brightness.

Since LCD's black levels aren't too great, black detail is easily crushed if I attempted to do a full 16-235 -> 0-255 level expansion, unless I raise the monitor's brightness, which I don't want to do.
maxleung is offline  
post #387 of 486 Old 03-02-2007, 10:09 AM
 
ChrisWiggles's Avatar
 
Join Date: Nov 2002
Location: Seattle
Posts: 20,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Charles Black View Post

Ozy

Ffdshow is a good way to have an HTPC expand the 16 to 235 studio video levels to levels 0 to 255 which is correct for a PC monitor. As an added bonus it will also pixel double as well so that there is a lot less pixelization with DVDs. I would try that first if your HTPC is up to it since you may not notice any banding (I never see any banding!) and certainly no posterization. Ffdshow is a good place to do minor gamma adjustments too and can handle the RGB gammas individually. Many also use it to do some sharpening and de-interlacing. My main issues have been occasional short freezes of the image with computer O/S activity mainly related to hard to read disks and the XP file indexing service. If you HTPC is too slow stuttering can be a problem. Zoom player supports ffdshow and there are others as well. I have also calibrated my E8500 to studio video levels with equally satisfactory results but the level 255 internal setup screens and PC screens are in danger of burning the phosphor if the white reference is set to level 235. I use a Spyder2 Pro to make a profile that goes into the video card LUT giving a nearly perfect gray-scale calibration. If the CRTs are adjusted correctly the profile has little to do and is just barely noticable when clicking it on and off quickly. Some uses of the Spyder2 Pro have wanted the video to be not quite as warm looking. That is a matter of taste and is not really a problem anyway since Precal and Optical can be set to any temperature.

Charlie

I strongly recommend against using FFDshow to do this. Much preferred is to use VMR9 and set the registry values (for nvidia drivers) appropriately and it will expand. FFDshow uses 8-bit processing so you definitely WILL get banding if you engage the levels slider/expander option in FFDshow. It has been quite a while since I played around with this so I do not know if ffdshow has been updated or changed in this regards, but if you are going to do an expansion you want to do it right and use higher bitdepth to do it. If you let the video card/VMR9 do it, it should be 10-bit or higher and you'll avoid the really severe banding that you'll get with the ffdshow levels filter engaged which again is only 8-bit I believe.
ChrisWiggles is offline  
post #388 of 486 Old 03-02-2007, 10:57 AM
Senior Member
 
Charles Black's Avatar
 
Join Date: Sep 2003
Location: Lopez Island, Washington
Posts: 340
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Ozy,

If you are calibrated for BT601 input you could try Tom Barry's BT709ToBT601() avisynth filter in Ffdshow to see what the difference is.

As far as converting Rec.601 to/from Rec.709 goes... The transformation from one set of primaries to another set of primaries requires a linear-light 3x3 matrix transform. The results of this may be negligible according to Poynton. The correction for the luma coefficients being different requires a 3x3 transform and it will be significant, also according to Poynton. The transforms are easily obtained.

Charlie
Charles Black is offline  
post #389 of 486 Old 03-02-2007, 11:04 AM
 
ChrisWiggles's Avatar
 
Join Date: Nov 2002
Location: Seattle
Posts: 20,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Charles Black View Post

Ozy,

If you are calibrated for BT601 input you could try Tom Barry's BT709ToBT601() avisynth filter in Ffdshow to see what the difference is.

As far as converting Rec.601 to/from Rec.709 goes... The transformation from one set of primaries to another set of primaries requires a linear-light 3x3 matrix transform. The results of this may be negligible according to Poynton. The correction for the luma coefficients being different requires a 3x3 transform and it will be significant, also according to Poynton. The transforms are easily obtained.

Charlie

You cannot correct for the chromaticity difference between 709 and SMPTE C using a matrix transform.

You can correct for the matrix coefficient differences between 709 and 601 with a matrix transform if necessay if for some reason color decoding is not being done correctly.

It sounds like you are confusing the chromaticity difference with the matrix difference. These two things are distinct. Chromaticity is physical to the display, the matrix difference is just a signal-flow encode/decode issue. They're quite distinct.
ChrisWiggles is offline  
post #390 of 486 Old 03-02-2007, 11:40 AM
Senior Member
 
Charles Black's Avatar
 
Join Date: Sep 2003
Location: Lopez Island, Washington
Posts: 340
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Chris,

I have often wondered why you experience banding with Ffdshow since I never have. Is it visible at some levels and not others on your HTPC?

The most likely culprit would be having the black reference set too high (on a pedestal). That would make very dark levels be more visible than they should be might create visible banding.

Charlie
Charles Black is offline  
Reply Home Theater Computers

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off