Color correction broke on my HTPC

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kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Color correction broke on my HTPC

Post by kevm14 »

I use the Pantone Huey to make the corrections and then unplug the hardware. That has worked for years. Suddenly, I noticed the picture seemed bluer than it should be (like pre-calibration) and that's when I realized it didn't seem to be calibrated. I re-ran the utility and it did nothing. I uninstalled the video drivers and reinstalled them. Nothing. Same with the Pantone software. Nothing.

This link has some ideas:
http://pantone.custhelp.com/app/answers ... or-hueypro

#3 is out. It is supported.

I don't see why it would be #2 but maybe I'll try different drivers. Could have been some Windows Update that broke this.

#1 I also doubt. I never installed Adobe Gamma and it doesn't exist on my system.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Color correction broke on my HTPC

Post by kevm14 »

Totally removed the CCC and video driver again.

This time I let Windows Update install the latest (presumably WHQL certified) driver, which was 2011 instead of 2009. This time, the calibration seemed to work.

However, when I opened the preferences for the system tray program that runs, and switched to uncorrected and back to corrected, it got stuck in uncorrected. So I recalibrated again, which worked, and I'm not touching that setting. I bet it won't even hold on a restart but it's recording something so I'll wait. I don't know why this became so fragile all of a sudden.

Side note, my TV is dimmer when corrected, since a lot of the blue is removed to correct to the right color temp. I will have to recalibrate at night anyway (and clean the screen) since I think the day light may interfere with the gamma curve. It also performs a room light measurement before calibration which I usually prevent by covering the sensor. I'd rather calibrate the screen in the dark because that's when black levels really matter. I don't want it boosting black levels because it would look washed out in darker viewing conditions. I guess I'd rather live with harder to see black detail during the day, then have it be washed out at night.
kevm14
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Joined: Wed Oct 23, 2013 10:28 pm

Re: Color correction broke on my HTPC

Post by kevm14 »

I knew it wasn't right. Wanted to recalibrate in dark conditions and it broke again. I'm afraid it's OS related. But I'll do some research into this issue. The utility needs to recalibrate the video card look up tables for gamma, per color channel. For some reason, it's having trouble.
kevm14
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Joined: Wed Oct 23, 2013 10:28 pm

Re: Color correction broke on my HTPC

Post by kevm14 »

Screwed around with the video driver for a bit last night. I got it into a state where it had a black screen upon bootup and it took some effort to get it to work again. Still won't calibrate.
kevm14
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Joined: Wed Oct 23, 2013 10:28 pm

Re: Color correction broke on my HTPC

Post by kevm14 »

So my TV died about a month ago. I wanted to play some music so I got desperate and hooked up a very old 15" LCD to my HTPC. Had a lot of trouble getting VGA output to work. I think what finally worked was a totally cold start, even switching off the power supply. I should note that the video card is an ATI HD4670 with dual DVI outputs. I had a DVI to component adapter going to my TV. And when that broke, I used the DVI to VGA adapter (the video card must support this; it doesn't convert anything per se).

Anyway, in a whim, I tried the Huey calibration tool and it worked perfectly on the VGA monitor. Some people may conclude that the TV was dying and that's why it didn't support calibration. But I don't buy that, because the TV actually has no idea about the calibration at all. It's all done in the video card look up tables. So, provided the TV can display gray scale and colors (which I could before it died), calibration SHOULD work fine.

Maybe it was because of the format change from component to VGA.

And if that's true, hopefully when I get my next TV, that the HDMI output can also be calibrated.
Adam
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Joined: Wed Oct 23, 2013 9:50 pm

Re: Color correction broke on my HTPC

Post by Adam »

kevm14 wrote:...I had a DVI to component adapter going to my TV. And when that broke, I used the DVI to VGA adapter (the video card must support this; it doesn't convert anything per se).

...It's all done in the video card look up tables. So, provided the TV can display gray scale and colors (which I could before it died), calibration SHOULD work fine.

Maybe it was because of the format change from component to VGA.

And if that's true, hopefully when I get my next TV, that the HDMI output can also be calibrated.
You can drive component out over DVI-I. The video card detects what is connected at boot and outputs the correct signal. You can also drive VGA over DVI-I.

Either way, the video card should be able to load the calibration data during OS boot every time. If the TV was broken to the point where the HTPC couldn't properly identify it, its possible that it thought it was a "new" or "unknown" display so the driver didn't load the previously stored calibration data.
kevm14
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Joined: Wed Oct 23, 2013 10:28 pm

Re: Color correction broke on my HTPC

Post by kevm14 »

The video card doesn't identify anything over component because component has no protocol for this.

I don't think the TV has anything to do with it but I guess we'll never know, unless I connect my next TV via component and try a calibration. I don't think it will work. But hopefully it works over HDMI.
Adam
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Re: Color correction broke on my HTPC

Post by Adam »

kevm14 wrote:The video card doesn't identify anything over component because component has no protocol for this.
It can detect that component device is connected, but yes there is no EDID-type interface over analog connections.
kevm14
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Re: Color correction broke on my HTPC

Post by kevm14 »

I don't even know if I'd phrase it like that. VGA (HD-15 connector) supports monitor identification and that's analog.
bill25
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Joined: Thu Oct 31, 2013 2:20 pm

Re: Color correction broke on my HTPC

Post by bill25 »

This is a very thrilling thread about VGA and HTPC's. Is this 2001? I shouldn't talk, I want an 85 Monte Carlo SS and a some kind of a K plow truck...
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