HOW-TO: Calibrating Display to Match HTPC Output - AVS Forum
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post #1 of 486 Old 03-24-2005, 10:02 AM - Thread Starter
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This has been discussed many times in many threads, but to bring it to the top and give it a thread of its own, here is a basic rundown of calibrating your display to display the proper levels for video playback, DVDs in particular.

_______________

Basic Display Brightness/Contrast Controls Overview:


"Brightness" affects the amount of light in the darks/colors on-screen. So turning it up increases the overall "brightness" of the screen. But in fact you need to turn it up/down in order to set the black level of the display. That is to say, that by using "brightness" to adjust the amount of light in the screen, you are able to make sure that "black" has no light, and that 1%, 3%, 5%, 25% grey and so on are at the correct "brightness" (have the correct amount of light).

Contrast will set where the white level is on the display. This will make the display darker/brighter. Try turning it down all the way and see what happens. You set "contrast" where what should be white, and not 99% or 95%, is white. If you set this too high, the upper percentages bleed together and you lose details in whites, like clouds and white shirts, etc.


In display technology, brightness=black level, and contrast=picture=white level.

Read this for a basic rundown of adjusting by eye, and what the different user menu controls do:
http://reviews.cnet.com/4520-6463_7-...2.html?tag=dir

_____________________

Always adjust at your display device if at all possible. Adjusting the output through ffdshow levels, video card adjustments, Powerstrip, etc. can have adverse affects on the picture, such as creating banding, crushing blacks/whites, etc. Only use source-side adjustments for final calibrations if you have no way of adjusting levels on the display device.

If you use a computer with a computer monitor, that monitor should have come calibrated to PC levels to show a range of 0-255.

Using Overlay with PC levels of 0-255, DVDs should have proper levels for blacks and whites. This is because Overlay is being "expanded" in a sense so that reference black and white show up properly, even though those values are at 16 and 235, respectively, and should actually appear as dark grey and light grey. This may be done by clipping the values, depending on the video card settings. This is something you can check on your own if you wish to use Overlay rather than VMR9. To do this, use Overlay and turn up the brightness/black level adjustment on your display until you either see the btb information, or nothing where the btb information should be. The former means you have btb data of course, and the latter means that information is being clipped.


VMR9, the other main video rendering mode, done in 3D using video card hardware, rather than 2D like Overlay, carries the full 0-255 range of values. So when you view something with btb/wtw data, such as the THX dropshadow screen attached post 31 (second page of this thread) on a display calibrated to show 0-255, you see the btb information (values at 7 and 10) -- and reference black (16) and reference white (235) appear as dark grey and light grey respectively.. Although VMR9 carries the 0-255 range of data, you must confine that to 16-235 (or slightly above 235) to insure reference black/white are at the correct levels, or shown as black and white rather than dark grey and light grey. To adjust a display set to 0-255 PC levels, you lower brightness (black level) and contrast (white level / picture), using contorls on the display itself. If set correctly using proper tests (DVE, etc.), this will give you correct blacks and whites, and at the same time insure that you are leaving the btb/wtw data intact so it can be used by the display to create a more accurate picture.


A quick test for seeing if your display is set to PC levels is this post. Bring up the THX image attached to it, and see if you are at PC levels (0-255) or video levels (16-235). Another good tool to use are the image files created by 3no in this post. One represents the black end of the spectrum, and the other represents the white. The backgrounds are 0 and 255, respectively, IIRC, and each have 25 vertical bars from 1-25 and 230-255. If I need to quickly verify my brightness level on my DVI/HTCP, this is what I use.

The Phillips Pattern Generator, available HERE is also another way to fine tune PC levels, with the CRT Adjustment screens being especially useful, giving you 1%-5% steps on both top/bottom end for greyscale, plus red, green and blue.


_____________________


Viewing video that is set to video levels, meaning that the reference "black" is at level 16 and the reference "white" is at level 235, with room in the 0-15 and 236-255 range for extra data, such as the screenshots taken from DVE here ( http://mistermax.smugmug.com/gallery/429986 ) through Overlay or VMR9 results in the following:


Overlay...
This will get rid of, or "clip" 0-15 and 236-255, showing video levels (16-235) as they should appear, by expanding the 16-235 range to 0-255. This shows level 16 black at level 0 of PC levels, and level 235 white at 255. This stretches out the whole range of values and may create unwanted side effects because it discards or clips any information that may be encoded below/above 16 and 235. It does, however, allow DVDs to be viewed with black/white at the proper level without adjusting the brightness/contrast level of the display itself, which may be necesary due to the uses of the HTPC, constraints of the display, etc. etc..

VMR9...
This will maintain or "pass through" the full 0-255 range, keeping btb/wtw information, any data encoded below 16 and above 235, intact. So, what you have to do in order to calibrate going from 0-255 PC levels to achieve proper 16-235 Video levels for VMR9 DVD playback, is lower the brightness (black level) to show level 16 reference black, the lowest black on a DVD, to appear as "black" on the display (not dark grey, as it appears when the display is set to 0-255), and have all information/levels below that blend in with the black. Then you adjust "contrast" (white level) up so that level 235 reference white on a DVD appears as white, and all information/levels above 235 appear to blend in with the white* (see NOTE below for info on this contrast/white setting).



Which is better, Overlay or VMR9?

Well, the general consensus seems to be that VMR9 renders a better-looking picture with more detail and more natural colors. It also passes the full 0-255 range, where Overlay may or may not depending on different video card settings, etc. And whether btb/wtw values are clipped or not may not matter to you anyway. You can read Chris's Source Settings Guide and decided for yourself how important you think it is to preserve those values. I myself prefer VMR9, as do many others, and feel it provides a better picture, more natural colors, and more subtle details in textures, faces/skin, etc.. But ultimately the choice of which to use is your own. You may like the VMR9 picture better, or need to use Overlay because of other uses you have for your HTPC, etc.

From Ursa:
In deciding between Overlay or VMR, many people are concerned that they lose color information by changing reference black from 0 (in PC Video) to 16 (in Studio Video) and by changing reference white from 255 to 235. Since commercial video is mastered using Studio Video levels, there is no color information to be lost when choosing to use VMR9. In fact, the opposite is typically the case and is why hard-core HTPC users are excited about using VMR.

_____________________

How to calibrate your display for VMR9 to show video 16-235 levels, rather than 0-255 PC levels:


To check, use this DVE screen, either through your VMR9 Video levels DVD playback software (if you have the DVD), or on this website:
http://mistermax.smugmug.com/gallery/429986
This is a test for blacker-than-black and whiter-than-white, and shows grayscale and ramps. If your display is set to PC levels of 0-255, the spot where the white dots are for black will show grey, not black at the white dots, with true black not being achieved until the right side of the dots. And the black dots in the white section will show a very light grey at the spot where the dots are, with true white not being achieved until the very left side.

To calibrate your display to show Video levels of 16-235, as they should be for DVD playback in VMR9 (Zoom Player), adjust the brightness (black level) adjustment on the display DOWN so that the greyscale block below the white dots is black, and that the spot in the greyscale gradation right at the white dots is black, you can still see grey to the left of the dots, and to the right of the dots appears as all black. Then adjust contrast (white level) UP the same way, so that the greyscale block below the dots is white, the point in the grayscale gradation at the dots is white, with visible grey to the right of it and all white to the left of it. (NOTE that I'm referring to the top half of the shot. You will probably need to open up the ORIGINAL size, save it, and show it on a screen with a black background to be able to see the black end of the scale easier). Note that if you try to view any image/picture, etc. that has important black/dark detail down below 16, that detail will be lost at this video levels 16-235 setting.

This is just one good example of calibrations screens that show btb/wtw information to help calibrate black/white levels. There are many other screens and other DVD setup discs as well. However, I have heard that Avia Pro has BTB/WTW screens, while the regular Avia does not - something to investigate and be aware of.

(Added 4/15) One thing to be aware of with digital displays is, it may not be ideal to calibrate white level (Contrast setting) to put your display's peak white at the 235 level. There are various reasons for this, including keeping an overhead range available for possible information encoded above 235 on certain DVDs, in order to maintain that detail. But with digital displays, you may find that your display is capable of very, very bright whites, much higher than they need to be. And trying to set this highest white the display is capable of may adversely affect the picture. See my Case Study using Finding Nemo below for my own experience with this issue. (/end new addition)

Now, if you are using some other playback software with VMR9 or Overlay, and you find that the above information for Overlay and/or VMR9 doesn't match, all you need to know is that all you have to do is calibrate with a test disc playing through that software to get the correct white/black levels, and you should be fine - for black/white levels at least, as color calibration is another story (see this thread for that: http://www.hdtvarcade.com/hdtvforum/...pic.php?t=1482 ).




REMINDER: When using the DVE test disc to calibrate, screens are shown as static images. This means you may have to skip chapters forward and then back to view any changes made in the software side. Avia and Avia Pro show patterns as actual running video, so changes can be made in real time. However, be aware that the commercial version (non-Pro) of Avia does not feature proper btb/wtw tests, so DVE may be a better choice for such tests. -- Thanks, Chris, for this addition.

**NOTE:** As mentioned in Chris's Source Settings Guide, some people prefer to set the white level so that "white" is above 235. The reason for this is because it helps preserve details that may be encoded on the DVD above the 235 level. So "235" will be slightly below the "white" level of the display, and any bright information that may fall above 235 on a DVD, such as cloud detail, details in white shirts, etc., can be displayed. Whether you set your white/contrast level to sit at 235 or slightly above is up to you. Again, refer to Chris's Source Settings Guide to see both sides of the discussion.


Here is the long, technical explination behind all that, the "Go-To Guide for Source Options" by ChrisWiggles:
http://www.avsforum.com/avs-vb/showt...hreadid=494606

And here is a thread on using calibration disk test patterns. (Added 4/20/05)

_ADDED 3/28_______________________________


Calibrating for Digital Displays - Case Study == Using Finding Nemo as a Gauge:
(NOTE: This is based on my own experience calibrating my Samsung DLP, so your mileage may vary with your own display)


While the brightness/black level adjustment advice holds true, and you should match the brightness setting to show level 16 blacks as black, with good gradation up from there, with digital displays the contrast/white level setting may not work the same way.

The idea of course is to set the darkest black your display is capable of to be at the level 16 black, making sure you can see detail in the dark values, etc. But on some digital displays, like my DLP, the display is capable of extremely bright whites. I found that if I adjusted the contrast/white level setting in my service menu up until I found the brightest white it is capable of producing, and set that level to level 235 white, the upper range of the greyscale was adversely affected, shifting to yellow or red at certain %'s.

For reference, the "normal" contrast setting in my service menu is about 103. I could take it up to about 125 to produce the brightest whites the set is capable of, and depending on the level of the red/green/blue gains, I could take this up to 130-140 and get the "brightest white" the set can produce set to 235.

When I tested out DVDs with this higher contrast setting, they all seemed to look fine, albeit brighter than I remember them of course. But one DVD was extremely messed up, with banding, macroblocking, etc. I had seen banding on the DVD before, and was aware that it could show such problems if the display (and video chain) aren't up to par. The DVD? Disney's/Pixar's Finding Nemo, of course. The PQ of this DVD has been fervently debated, some people saying it's perfect reference quality, and others saying it has banding, blocking, etc., and then the people who don't see those issues say it's the video chain/display that's bad if you see issues. See this thread, started late 2003, to see what I'm talking about.

So, with my high contrast settings, thinking I was setting the "white level" at the correct spot, Finding Nemo looked like trash. Banding was slight with certain scenes, but at the end of Chapter 14, when Marlin and Dory come out of the swarm of jellyfish, I saw 3! colors of blue, with saw blade-like blocking between the different tones. Lost and trying to tweak levels, I spent the better half of Saturday (much to my wife's dismay) "fiddling" with the TV and computer. I settled on some decent settings Saturday night, something I could be satisfied with (for a day), back at an acceptable level of banding on Finding Nemo that I had grown accustomed to seeing.

But I was obsessed with nailing down the settings to get Finding Nemo to look better, even though every other DVD I tested looked "fine". So Sunday, I spent about 2-3 hours (took much less time this time) tweaking. I started off by lowering my contrast down to around the previous level, and the extreme banding in the scene described above went away. So from there, I used DVE greyscale screens to adjust red/green/blue gain/offset balance. I had a hard time with this, and found that using the Phillips Pattern Generator a much more complete and convenient tool, although I still checked the DVE screens for black level and overall status. The Phillips Pattern Generator has greyscale bars and many other test patterns, but I found the CRT color/b-w adjustments to be the most useful. I was able to nail down the red-green-blue gain/offset adjustments with the greyscale bars. Then I nailed down the contrast level and color saturation (in the user menu) to create a proper 0-100 gradation for each color, with clear distinctions at the 1%-5% steps on both the top and bottom end (although the bottom end, about 0-10% or so, required moving brightness/black level to 0 instead of 16 temporarily). Too much contrast, and the upper range of the colors bands together, as seen in the Finding Nemo example. The same applies to the Color saturation setting, as too much color will lose the differentiation between 100% and 99%, etc. Working through my Samsung's Service Menu reverts the user menu controls to the "Dynamic" mode, which has Contrast at 100/100, Brightness at 50/100, Color at 65/100, and Sharpness at 65/100(?). So after getting the brightness and contrast levels dialed in with the service menu, I exited and went back to the user menu controls to turn off the sharpness and dial down the color to fine-tune the color gradations and get proper differences between single % changes with the Phillips program.


Basically, this meant that for my digital Samsung DLP display, I lowered my brightness/black level to set "black" at 16. But I kept my contrast/white level lower, not going for the absolute brightest white it was capable of. I went for the proper greyscale gradation through the whole 0-255 range using the Phillips Pattern Generator, aside from the lowered brightness for black=16, and found those results were the best. The "white" level appeared light grey compared to the maximum white the display can achieve on a greyscale ramp, but even at the lower contrast/white level setting, a screen of all "white" is still plenty bright, and looks "white" anyway.

I was a little nervous as I brought up Finding Nemo, but was pleasantly surprised. On all scenes tested -- 0:30 opening, aquamarine-colored water under "butt" boat, Dory's blue skin/scales at the beginning of Chapter ? right after Marlin and Dory first meet, water around deepsea fish's antenna, water where Marlin and Dory come out of jellyfish swarm, etc. -- banding was gone or reduced to so slight a level I had to stare and look to see it. I couldn't have been more pleased with myself, and the results, and every other DVD I tested looked great like before, with seemingly better gradations, colors, detail, etc. I had a good calibration before, after I got my new light engine installed a few weeks ago, but redoing it (light bulb losing a bit of brightness after first 100+ hours of use, etc.) this time, I think I have my settings better than ever before. And there is less noise in the picture than I remember from before as well - on the DVDs I tested, I could only make out the noise by pausing the DVD and advancing frame by frame.


Lessons (I) learned from this experience:

A) Digital displays can be very finicky, where a CRT may seem to hide/blend colors together for less banding, at least with DVD sources, or computer+DVD sources.
B) The Finding Nemo DVD is a great test to gauge your digital display for proper color/br/ct balance. If the settings are off just a little, you'll see banding and artifacts.
C) Brightness/black level is easy enough to set, but contrast can be a bit trickier (at least on digital displays with a high amount of light output), so testing with finicky real world material like Finding Nemo can help put things into perspective. Other DVDs with distinct green/red/orange/blue looks can also help see if you have your green or red, etc. up/down a few notches too far, as you can tell a green looks too green or doesn't have enough green more in a scene you know, than on a greyscale where it may not show up as well in the greys.
D) Using an HTPC as a DVD player gives you a lot of control and options that normal DVD players don't, not only with playback, but especially with calibrations. Being able to use the Phillips Pattern Generator, etc. to dial in my settings meant that I can have (near) perfect settings without needing fancy, expensive signal generators, light meters, etc. Too bad this only applies to the DVI/HTPC input.


So, that's my digital display calibration experience for you. Your mileage may vary, but hopefully some of this will help people trying to calibrate their own digital displays.

UPDATE: ADDED 4/29/05


GSB (Gary) has detailed a nice method of calibrating Service Menu adjustments on (Samsung) DLPs HERE by tying the contrast level to the maximum red to achieve 6500K color temp. I have not yet tried this method, but it seems to work very well.


UPDATE: ADDED 6/23/05


An easy way to check greyscale and color temperature, if you are using component cables, is to unplug the red/blue cables, leaving only the green luminance. This will produce a b/w image of whatever you are viewing. This may give you a better view of how your greyscale looks, and if there are any problems (discolorations from off-temps, etc). I myself used this technique recently to touch up my three component inputs (HD cable, Xbox, and STB DVD player).



UPDATE: ADDED 12/07/2005

In the Calibration forum here at AVS, there is a new CALIBRATION FAQ thread.
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post #2 of 486 Old 03-24-2005, 10:16 AM - Thread Starter
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BTW, Moderators -- I would say this even if it wasn't my own thread, but I think this would be a good candidate for a sticky on this forum...
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post #3 of 486 Old 03-24-2005, 10:19 AM
 
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Another thing to remember, is that if you are adjusting settings within the PC software, such as in TT, that VMR9 will only show you the changes if video is playing. With DVE this means flipping chapters back and forth. Avia and Avia PRO use moving patterns, so the video is playing and you should see the changes real-time.

Thanks cyberbri, this is a good writeup, I will be sure to keep it handy, and link it in my thread!

-Chris
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post #4 of 486 Old 03-24-2005, 10:30 AM - Thread Starter
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Hey, Chris. Glad to do it. And thanks for the addition. I'll add it to the top message.

I've written the same stuff over and over so many times lately, I thought I'd take the latest one and just make a new thread.

I know I've consulted your Source Settings Guide a number of times. It was a lot to process the first time, but after experimenting with my HTPC a lot, looking at test patterns, going between Overlay and VMR, I finally understood enough to really understand what all the technical talk (in your thread) is all about.
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post #5 of 486 Old 03-24-2005, 10:51 AM
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Not to be picky, but I "think" that what cyberbri has written about white level contradicts (may not be the right word - maybe disagrees) what it is in ChrisWiggles "Source Settings Guide."

For example, cyberbri recommends to clip WTW (blend in after 235) - which is what I do on my 4805. It gives me max contrast and after trying both, it works for me.

However, ChrisWiggles refrains from calling this WTW saying that we should not blend it - that we should see it, not clip it.

I was wondering if either of you had anything to add - I've seen many special members advice one or the other. Is it personal preference or is there really a "right" answer to this?

BTW, thanks cyberbri for doing this - it will really help folks. I had to dig around thread after thread to figure out all this stuff. It's nice that it has a thread of its own.

We contend that for a nation to tax itself into prosperity is like a man standing in a bucket and trying to lift himself up by the handle. (Winston Churchill)
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post #6 of 486 Old 03-24-2005, 10:58 AM - Thread Starter
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Yes, I thought about adding that but didn't want to confuse the issue. I will add a special note about wtw that it may be best to leave a little room for extra detail, and refer to the Source Settings Guide.

Will add now. Thanks.
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post #7 of 486 Old 03-24-2005, 11:05 AM - Thread Starter
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Chris,

As a suggestion, you may want to link this thread from Section 4 / HTPC on the first post of your guide, so it links to this thread rather than, or in addition to, the HTPC forum.


EDIT:
Chris, I just realized you're the guy with kexp in his sig. I'm originally from Seattle, and love KEXP. I've been in San Jose since January 04, but still listen to kexp streaming at work a lot.
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Quote:


Is it personal preference or is there really a "right" answer to this?

This is something I've discussed a bit in the later pages/posts in my thread, but I will not be so stringent as to say that clipping peak whites to maximize the CR range of a digital display is "wrong" but rather not generally ideal.

The "right" thing to do would be to use a CRT...

I would recommend including peak whites as visible at the display, but if you spend some time with each and prefer utilizing your limited contrast range differently, that's certainly your choice. Having spent a good bit of time with digital displays will full peak white displayed, I would strongly prefer keeping them like that rather than clipping.

edit: DJ Riz is my favorite of all time
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post #9 of 486 Old 03-24-2005, 11:43 AM
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Quote:


it helps preserve details that may be encoded on the DVD above the 235 level.

Quote:


I will add a special note about wtw that it may be best to leave a little room for extra detail

It would be great to show some A/B frame grabs that document this extra detail'. At least some titles and timestamps? I tried to here.

Dave
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post #10 of 486 Old 03-24-2005, 12:14 PM
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Cyberbri - good write-up! This will help a lot of folks out. One thought, though, is to make sure that you distinguish reference white and reference black from peak white and peak black. Digital 16 in sRGB is reference black, not the "lowest" black. Similar is true for digital 235 and white. If you set your absolute black to 16, and your absolute white to 235, then that is when clipping occurs. Of course, calibrating this distinction (i.e., getting a good gamma at a near-constant color temperature of 6500K) is probably the trickiest of any of the steps.

You may want to reference Charles Poynton's website (http://www.poynton.com/) for folks to read his FAQs on Gamma and Color (even though it is referenced in Chris' thread as well). Also the biology of spectral response here: http://www.poynton.com/PDFs/Guided_tour.pdf is really good for those trying to translate the (outdated now, I guess) traditional spectrum of light into the biology of color. I know it got me over a few big hurdles.

Later,
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post #11 of 486 Old 03-24-2005, 12:38 PM
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Nice work! Maybe later you can incorporate an Advanced section detailing the use of DGIndex to make reference framegrabs and using the print-screen method to capture VMR9 output and comparing RGB values. This will ensure that no clipping is done on the PC playback side.
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post #12 of 486 Old 03-24-2005, 12:58 PM
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Quote:


Originally posted by maxleung
use of DGIndex to make reference framegrabs and using the print-screen method to capture VMR9 output and comparing RGB values.

This method doesn't work on an ATI Radeon 9700 Pro. When I change the contrast/brightness it must do it in hardware.

For example I used DGIndex to save a calibration image from DVD to bmp format using IEEE-1180 Reference and TV Scale. I opened up the .BMP calibration image in photoshop and noted the colours, black RGB=16,16,16 and white RGB=235,235,235. I changed my default color settings in the ATI Catalyst control panel and took a printscreen screenshot when black looked black and white looked white. When I checked the colours in photoshop, black was still 16,16,16 and white was 235,235,235. On Nvidia cards I presume when you change the contrast/brightness, and press printscreen, then paste it into a paint program like photoshop, the eyedropper tool picks up the changes in the brightness/contrast?

If it doesn't how can you compare what the real colour is when changing brightness/contrast and checking with printscreen/eyedropper in paint.
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post #13 of 486 Old 03-24-2005, 02:48 PM
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To be more general, the method I have outlined works to only guarantee that your DVD playback software isn't modifying the video outputs out of spec (ie. away from studio RGB). You want the playback chain until just before the display device to be as clean as possible!

Your best bet is to always leave the videocard's color controls at neutral (ie. default) values as much as possible, and calibrate your display only.

The only way to be absolutely sure the colors you are getting on your display are accurate, after ensuring the playback chain is clean, is to use a colorimeter (or scope it).

Changing brightness, contrast, saturation, gamma, etc should never be done on the PC side as much as possible - unless there is a display device deficiency that can't be overcome through the display's controls. For example, a CRT device's gamma that is too high - you would need to use something like Powerstrip's gamma profiles to compensate in that case (or the ATI control panel or whatever).

BTW steve, your comment can apply to all modern videocards - they all allow you to change brightness/contrast/color in the display panel. You have to trust that they are set to neutral values by default. I believe they should never be touched unless absolutely needed.
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post #14 of 486 Old 03-24-2005, 02:56 PM
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Originally posted by maxleung
BTW steve, your comment can apply to all modern videocards - they all allow you to change brightness/contrast/color in the display panel. You have to trust that they are set to neutral values by default. I believe they should never be touched unless absolutely needed.

How much can we trust that they ARE neutral? I'm assuming that we need equipment to tell for sure.

On my x700 pro, I have everything at default, and calibrated TT 2.1.18 with DVE blue filter to basically perfection.

Since it is perfect with DVE blue filter and color bars, I am good to go, right?

Oh and the reason I adjusted TT color controls and not my 4805 color controls is because over progressive, color and tint are not available.

We contend that for a nation to tax itself into prosperity is like a man standing in a bucket and trying to lift himself up by the handle. (Winston Churchill)
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post #15 of 486 Old 03-24-2005, 03:03 PM
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Yeah, we would definitely need equipment to be sure!

You have a great example there for why the color controls on the PC need to be fiddled with. The DGIndex method is great for establishing a baseline - but if you can't adjust the display directly at least you are starting from a reference point before you hammer on the PC controls.

If everything looks good to you, then you're good to go.
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post #16 of 486 Old 03-24-2005, 05:55 PM
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I have a Mitsubishi DLP TV. A WD-52525. I have Media Center. I am using a normal VGA cable as the input to the TV. The RGB input on my TV bypasses most of the filters (sharpness included). I can still adjust contrast and brightness, though. I get a perfect 1:1 pixel ratio with the VGA input.

I can adjust the brightness on the TV so that the top 2 bars are black. But I can't adjust the contrast high enough so that the bottom 2 bars are white. If I am reading your post right, that is what you want to have happen.

Is your post correct for calibration of my setup?

If I can't get the top 2 whites to be the same level, should I venture into the contrast setting for the video card?

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post #17 of 486 Old 03-24-2005, 06:20 PM
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I'm not sure what screenshot you are referring to...can you clarify?

You might be okay anyways...in the meantime, try watching some DVDs or other demo material and see how it looks.
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post #18 of 486 Old 03-24-2005, 06:25 PM
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I'm talking about this one:
http://mistermax.smugmug.com/gallery/429986/1/17263868

The one that pops up first.

DVDs look awesome with the adjustments I made. I, Robot, in particular is amazing.

But recorded HDTV looks a little washed out, and they are both using the same MPEG2 decoder.

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post #19 of 486 Old 03-24-2005, 10:38 PM
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When you say top two bars, I guess you meant the leftmost black bars on the bottom of the screen? Yeah, they should be black.

The rightmost white bars on the bottom part doesn't matter as much - they can both be visible. In fact, it is probably better that way - you will preserve white detail (like little details in clouds) better. So you should be fine.
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post #20 of 486 Old 03-25-2005, 09:32 AM - Thread Starter
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EDIT 3/25:
Modified certain areas of the above. As pointed out by Owen on a different thread, VMR9 uses, or displays, PC levels of 0-255. This is why when your display is calibrated to PC levels, using VMR9 to view DVE screens, etc., black-16 appears as black-16, and you can see all the way down to btb-0 on the test screens. Because VMR9 is showing the whole PC levels 0-255 scale, you have to adjust the display and set the black/white display levels hide that. Overlay, when viewed on a display set at PC levels, shows 16-black as the blackest area. Whether it is passing 0-15 and 236-255 information may depend on video card settings, etc. But VMR9 is still recommended for picture quality and because you are ensured you hae 0-15 and 236-255.
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post #21 of 486 Old 03-25-2005, 10:08 AM
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VMR9 uses studio levels. Overlay uses PC levels. That's the reason VMR9 can preserve BTB/WTW data. Studio levels place reference black at 16 and ref white at 235. PC levels place black (reference and absolute) at 0 and white (reference and absolute) at 255.

Your text is mostly correct in terms of the effects of the differences between VMR9 and overlay, but your terminology is wrong (or at the very least, quite confusing)
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post #22 of 486 Old 03-25-2005, 10:24 AM
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This is the part that reads a bit misleading to me:

Quote:


Viewing a DVD in VMR9 -- or viewing an image that has video levels, meaning that the lowest "black" is at level 16 and the highest "white" is at level 235, such as the screenshots taken from DVE here ( http://mistermax.smugmug.com/gallery/429986 ) -- what should be "white" (235) appears at 235 out of 255, or a slight grey, and what should be "black" (16) appears as 16 out of 255, or dark grey. Viewed on a display calibrated to PC levles, 0-15 and 236-255 appear visible as well. But you don't want this when watching DVDs.

Change "lowest black" to "reference black" and "highest white" to "reference white" and you will be much clearer for the average user struggling with BTB and WTW (and who does not want to read Don Munsils and Stacy Spears posts linked in Chris Wiggles' settings thread, or any of Charles Poynton's stuff...).

Later,
Bill
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post #23 of 486 Old 03-25-2005, 02:27 PM
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Quote:


Digital 16 in sRGB is reference black,

I don't believe that the term 'sRGB' (Standard RGB) is synonymous with the term 'Studio RGB'. sRGB uses the range of 0-255 for 8 bit integers.

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The nonlinear sR'G'B' values are then converted into 8 bit integers by:
R8bit = round(255.0 ´ R'sRGB)
G8bit = round(255.0 ´ G'sRGB)
B8bit = round(255.0 ´ B'sRGB)

See http://www.srgb.com/basicsofsrgb.htm

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post #24 of 486 Old 03-25-2005, 02:50 PM
 
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I'm not very familiar with a term "sRGB" further, this appears stylisticaly similar to "RGBs" or "RGsB" where "s" means sync. Thus I don't think the term "sRGB" is really a good one, or clear. Saying Studio RGB or Studio Levels is probably more appropriate, and PC RGB or PC Levels. (Of course, for complete clarity, one may want to prime R'G'B', but I don't feel it's needed unless you are in an engineering environment, and then you should know enough to know...)
Further, I also tend to think that saying that a system "Maintains Video Levels" or incorrectly "Expands to PC Levels" is the most clear you can be.
If you have test material, stating that it is "at PC Levels" or "Studio Levels" has gotten ambiguous for me, as a pattern that includes the full 0-255 range, including outside nominal reference white and black for video, you might say is "PC Level" pattern, but to maintain it correctly all the way would require maintaining Studio Levels. You can see why this can confuse some people.

So a statement like this one is very unclear to me:
Quote:


sRGB uses the range of 0-255 for 8 bit integers.

Both Studio RGB and PC RGB use the 8-bit range 0-255. It's *HOW* they use that range that varies, and how data points within that range are used to define image attributes. This is why loose terminology can be problematic, and why I really try to be, if anything, redundant when dealing with these topics, to make sure everyone is on the same page when we're discussing things.
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post #25 of 486 Old 03-25-2005, 03:21 PM
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Quote:


Originally posted by Sokoloff
VMR9 uses studio levels. Overlay uses PC levels. That's the reason VMR9 can preserve BTB/WTW data. Studio levels place reference black at 16 and ref white at 235. PC levels place black (reference and absolute) at 0 and white (reference and absolute) at 255.

Your text is mostly correct in terms of the effects of the differences between VMR9 and overlay, but your terminology is wrong (or at the very least, quite confusing)

Now there are two conflicting posts in this thread - one states that vmr9 displays 0-255 (PC levels).

This quote states that vmr9 displays Studio levels (16-235). This is what I thought as well - and that overlay uses 0-255.

Which is it

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post #26 of 486 Old 03-25-2005, 03:24 PM
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Quote:


Thus I don't think the term "sRGB" is really a good one, or clear.

Blame HP and MS. It's also known as IEC 61966-2-1 see http://www.w3.org/Graphics/Color/sRGB
Quote:


Hewlett-Packard and Microsoft propose the addition of support for a standard color space, sRGB, within the Microsoft operating systems, HP products, the Internet, and all other interested vendors.

Quote:


Saying Studio RGB or Studio Levels is probably more appropriate, and PC RGB or PC Levels.

Agreed. I've just seen the term sRGB used here as a synonym to Studio RGB and I think they are different standards and not interchangeable.
Quote:


Both Studio RGB and PC RGB use the 8-bit range 0-255.

No, Studio RGB does not use values of 0 or 255 to represent data. PC RGB (and sRGB) does.
Quote:


This is why loose terminology can be problematic

Agreed.

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post #27 of 486 Old 03-25-2005, 03:26 PM - Thread Starter
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Quote:


Originally posted by Ursa
This is the part that reads a bit misleading to me:



Change "lowest black" to "reference black" and "highest white" to "reference white" and you will be much clearer for the average user struggling with BTB and WTW (and who does not want to read Don Munsils and Stacy Spears posts linked in Chris Wiggles' settings thread, or any of Charles Poynton's stuff...).

Later,
Bill


I will make those changes.
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post #28 of 486 Old 03-25-2005, 03:30 PM
 
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Geno, again, this is why terminology can get confusing. I actually addressed this in a roundabout way in my post.

VMR9 *Maintains* Video levels, while Overlay *expands* the video range to PC levels. BOTH use the 0-255 range, but they use it differently. VMR9 *maintains* Video levels properly, and maintains the data on the disc, which is (quickly for simplicity) 0-255, with the nominal reference range of 16-235. If you use overlay, or otherwise perform an expansion to PC levels, that range will be expanded such that 16-235 is now mapped to 0-255 and values outside the 16-235 range will be clipped.

Quote:


Now there are two conflicting posts in this thread - one states that vmr9 displays 0-255 (PC levels).

I'm not sure where that is stated/inferred.
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post #29 of 486 Old 03-25-2005, 03:32 PM
 
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Dave:

Quote:


quote:
--------------------------------------------------------------------------------
Both Studio RGB and PC RGB use the 8-bit range 0-255.
--------------------------------------------------------------------------------


No, Studio RGB does not use values of 0 or 255 to represent data. PC RGB (and sRGB) does.

I was being simplified for a moment, and while codes 0 and 255 are illegal in video, they can actually be coded for image content. There are patterns on Avia PRO that contain codes 0 and 255 as image content. They are the only illegal values in Studio RGB.
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post #30 of 486 Old 03-25-2005, 03:42 PM
 
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Dave, BTW thanks for the sRGB link. It is interesting, though it's all the more reason not to use sRGB as a term to mean Studio RGB, as it's very obviously PC Levels and Graphics-defined colorspace, not for video applications.
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