Callibrating colors

[jbarr]

OK, I'm getting close to getting things looking good on my SageTV and new Westinghouse W4207 HD Monitor. After a number of tweaks here and there, I think I have the video looking as best as SD cable can be, but I now find that my colors are off.

As I see it, the best (only?) way to effectively callibrate colors is to adjust up to three main places:

1. Calibration of the both Hauppauge PVR-150's through SageTV's Color Calibration screen
2. Tweaking of colors through nVIDIA's display drivers
3. Tweaking colors on the W4207 HD monitor

So my plan is to reset everything to factory defaults, and start from the top. Obviously, each source will need to be tweaked independently to get them to match as best as I can. Then the display drivers would need to be tweaked. Then the HD Monitor would get adjusted.

I guess I could display some color bar images on the HTPC and callibrate the display drivers and HD Monitor to THAT, then go back to the sources and adjust them independently.

Does anyone have any other suggestions as to the best way to callibrate colors?

[IncredibleHat]

I find adjusting the tuner cards first is a better way to go, as they 'record' that calibration... so you have to make sure its recording proper. Only way I know to do that correctly, is to use a histogram type filter overlay while calibrating the cards. Ugly process, I ended up using dscaler (ugh I hate that thing).

Then from there, I did a small tweak to the nvidia control panel with a 'test pattern' visible on the desktop. I know thats not video, but it gets the 2d more rich. I then adjusted it a little (not much) for video playback which a video playing with a test pattern. To get the blacks to fall right, and whites etc.

I didn't touch my TV settings much, as it was basically set from that point. I only tweaked my 'brightness' setting a bit to get the 'blacks' from the htpc to look more close to the 'null black' of the pilarboxing (when in an aspect ratio for that). So that it wasnt a stark difference between the pilarboxed black, and the blacks in playback.

However, right now I've got a weird issue with my nvidia drivers, that looks like its posterizing the colors. I think its these new 93.71 drivers, they fixed a problem with my 6150, but the color quality is really crap (even with their reg hack suggestion).

The other issue I have, is my wastinghouse 42" HD monitor has this band (about 3 inches wide) on the right side that doesnt display 'greens' the same brightness as the rest of the screen. I cant seem to get any response from WH about this, so I dont know if its something covered under the bestbuy plan or not. But that has nothing to do with color calibration

[blade]

It is generally recommended to make all of your adjustments on the display if possible. Of course calibrating your capture cards are the exception. The HTPC playback settings are the last thing you should be adjusting if you adjust them at all.

Obviously the display is what you actually see so if it's not correct you're going to be over compensating with your HTPC settings to try and correct problems with the display.

I admit once I got my display and capture cards as close as I could I did make a few minor tweaks to my HTPC settings. One of the downsides to making adjustments on the HTPC is that it's easy for the settings to get changed. After upgrading drivers I've sometimes found my settings were reset to default, if you made changes to the decoder settings choosing a different decoder will really throw everything off, if you ever do a format and fresh install you're starting over from scratch with your calibration.

[kricker]

I agree with Blade. That's exactly how I set mine up as well. After all I use my TV for direct cable viewing, and before my HTPC, an external DVD player, it's built in memory stick viewer and an xbox. So it was very important the the display is setup properly first. This holds especially true in a multi TV viewing environment. If all your displays are not setup correctly, then adjusting the capture settings on one TV can really make them look like poo on a different TV. Of course two difffernt display devices will never ever look the same, but never the less you should try to get the setup a best as possible before you start messing with anything else.

[Polypro]

Here's how I do it:

1. Calibrate the Windows Desktop: Go to AVS's HTPC and Calibration forums (or try Google Images) and find 0-16 Brightness (Black Level) and 235-255 Contrast (White Level) images. Then grab an SMPTE Color Bars image. Get .bmp, .gif, or .png images, not .jpg, if you can. Get a Blue Filter (If you don't have one, go to Circut City and tell them you got an HDTV from them, but there was no Calibration pack inside. These contain Blue Filters and they have millions in the store that they remove from returns...or buy a blue filter). Make sure your graphics driver is zeroed out (in the middle, default) for it's settings. Use the TV controls to adjust B/C to PC levels - 1 & 254 barely visible. Looking through the Blue Filter, put up the SMPTE bars and adjust Hue/Tint so that Cyan and Magenta are the same color...and Color/Saturation so that Blue and White (or Gray) are the same color. The reason I calibrate the desktop to PC levels is that websites or forums look too dark when calibrated to Video Levels.

2. Calibrate SageTV to Video Levels Step 1: Your going to need a calibration disk. The one you might get from Circut City may do, but if you've got $25, AVS forum member "GetGray" made a great disk that can be downloaded:

http://www.avsforum.com/avs-vb/showthread.php?t=586139

http://www.calibrate.tv/

alternatively, there are some small calibration clips available in the above mentioned AVS forums. Either way, open up Sage in a window and play the clips/DVD. Double click the nVIDIA tray icon and open its config screen. Go to the color tab and like above, adjust Black Level so everything below 16 is the same color, and everything above 235 is the same color. Adjust Hue and Color like above. This will calibrate DVD's (either ripped or rented) and HDTV. Downloaded videos will be at the mercy of who encoded them.

3. NTSC through your capture card: Once you know your TV and Sage are at the proper levels, you just need to make your capture card is the same. I do it by running the calibration DVD through an RF modulator and adjust the cards' settings as above. There is also an FFDSHOW histogram available, but after you get the hang of it, you can probably do it by eye. Can you see the detail of a white shirt or snow scene? Dark suits? Skin too red?...green?

That's how I do it. It may not be the best way...may not be the right way...and isn't the only way

Notes:

1. I use nVIDIA decoders, 84.21 drivers, PVR500's, and VMR9/FSE via DVI. My display is an Olevia 542i LCD. YMMV with different stuff.

2. Some nVIDIA drivers remap Video to PC levels via DVI. There is a DWORD setting called VMRCCCSStatus that needs to be added to the registry to fix this. A setting of 1 keeps the desktop at PC levels, and video at video levels.

http://www.avsforum.com/avs-vb/showthread.php?t=718498

P

[kricker]

Originally Posted by Polypro

...
2. Some nVIDIA drivers remap Video to PC levels via DVI. There is a DWORD setting called VMRCCCSStatus that needs to be added to the registry to fix this. A setting of 1 keeps the desktop at PC levels, and video at video levels.

http://www.avsforum.com/avs-vb/showthread.php?t=718498

P

Is it really 1 or is it 3? I've read thru threads at AVS foum and others multiple times in the past and there seems to be some confusion as to which it should be.....at least it's confusing to me.

From the release notes:

Video color-space range for DVI-only* outputs is erroneously set to
standard mode (16-235) instead of extended mode (0-255).
A new detection feature to apply Standard CSC mode to TV outputs
(including NTSC, PAL, 480i, and 576i), included DVI-only outputs by
mistake.
Note: The driver correctly applies extended mode to analog outputs, and
standard mode to TV outputs (including NTSC, PAL, 480i, and 576i).
A future driver release will correct this and apply the extended-mode color
space to DVI-only outputs.
You can work around this issue by forcing either standard or extended mode
as follows:
* “DVI-only” means only one display is connected, and it is to the DVI output.

1 Launch regedit and determine the current primary display card by
looking in
HKey_Local_Machine\Hardware\DeviceMap\Video
and note the GUID (global unique identifier assigned by Windows),
which is the long string in brackets { } at the end of the entry
ʺ\device\video0ʺ.
2 Look in
HKey_Local_Machine\SYSTEM\CurrentControlSet\Control\Video\
{GUID}\0000
where {GUID} is the number derived from the previous step.
3 Open the ʺ0000ʺ directory and create a new DWORD called
VMRCCCSStatus and give it a value of
0x3 - to force use of the standard YUV range of 16-235
0x1 - to force use of the extended YUV range of 0-255

[Polypro]

I have it at 1. If you read further in that thread I think they clarify it. Anyway, there's an easy way to tell. If you don't have to move the decoder sliders hardly at all to get 16 & 235...your video is at PC levels.

"Be aware that with the 84.xx drivers you may need to use the VMRCCCSStatus registry hack to preserve video levels (the entry should be a DWORD set to 1 for video levels, 3 for PC level expansion).

For more details you'll need to do a search."



P

[Crashless]

FWIW, I'm a professional editor and I often color correct shows for a living, and I always calibrate as much as I can at the display level, defaulting all other settings.

When you start messing with encoder calibration, decoder calibration, video card calibration THEN display calibration it is FAR too easy to crush blacks and whites, and get color so far out of whack that there's no way to get it normal again.

The only exception I've ever had is on a television that had really poor color controls, in which case I did the best I could at the TV, then applied a _tiny_ bit of color adjustments at the video card level.

Best of luck!

[stanger89]

Just to reiterate what's been said above, the only place you want to adjust is the display. Ideally, all calibration should be done there. DVD is the "gold standard" as far as output goes, it's correct. The reason you need to do capture card calibration is because the default settings aren't normally correct, ie they don't match DVD, so you calibrate the capture settings so that all your media "matches".

Video is supposed to be 16 == nominal black, and 235 == nominal white, with allowance for excusions beyond that. This is the way CE devices opperate and the way video is meant to be decoded, transmitted, and viewed (on a properly calibrated set).

You don't want to adjust settings in the playback chain unless you absolutely have to, no other option. And then the best place to do it (or maybe least bad) is the video drivers, since they usually operate at the highest precision.

Oh, and FWIW, "PC Levels" are a range of 0-255 with black == 0 and white == 255.

Video, per ITU-R BT.601 (SD) and ITU-R BT.709 (HD), specifies a range of 1-254, with 0 and 255 being reserved values (for sync and such) and 16 and 235 being nominal (sometimes called "Video") black and white respectively.

[kricker]

Should someone consolidate this and place it in the FAQ or make it a sticky? Seems like something that could benefit everyone. Sure AVS forums has information about this, but it'd probably be good to have some of this basic stuff answered here for all to see as well.