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.
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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.
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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.
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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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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.
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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.
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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 .