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Old March 31st, 2003, 01:37 AM   #1
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Adjusting computer monitor to be fairly accurate.

I edited a piece for a show I'm working on, and it looked okay on my computer monitor. On this other guy's laptop monitor (and, he says, at his home computer): way to dark!

The piece was badly lit and dark to begin with, but I brightened it some in post until I could (according to my computer monitor) see detail where I needed to.

I don't have, nor do I want to buy right now, an NTSC monitor. I figured my the preview window in Vegas 4 (which I used to edit) would be the most accurate thing I have right now with which to judge color, contrast, brightness, etc. Now I'm not sure I can even trust it. I'm wondering if anyone has a method to calibrate the computer monitor to be fairly accurate, so that I can be sure what I see is close to what others would see on TV or their respective monitors.

I know all monitors are different, as are TVs, and that the Sonic Foundry codec affects what I see, but nevertheless, it'd be nice if I could be confident when I edit. It's a sort of old computer monitor (from '99, I think), with all the simple controls for brightness and contrast, color, etc.
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Old March 31st, 2003, 02:47 AM   #2
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Josh,
You can try walking through the monitor calibration procedure at Video University. To a great degree, however, you're chasing a rainbow. Computer monitors, whether CRT or LCD, display images fundamentally differently than televisions. Their color systems are different, the gamma curves are different, etc. If your target display venue is a television you really need to use a CRT monitor, or at least a consumer tv, to judge your image.

But it sounds like you're judging your image against a friend's computers rather than a tv?
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Old March 31st, 2003, 03:03 AM   #3
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Yeah, you're right. But it was dark as hell on his laptop, and he said it was the same on his home computer. I figure that's two strikes against me. If it was just his laptop than I wouldn't be as worried. It looks fine on the cheapo tv I'm using as a monitor, but then, you can screw with brightness and contrast on those. . .so who knows.
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Old March 31st, 2003, 05:21 AM   #4
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If your friend was using a Mac, the brightness change is normal. Mac's and PC's use a different native gamma (Mac's 1.8 / PC's 2.2). Before you start adjusting things check the images on a TV (if the program is intended to be viewed on a TV) and see how it looks. If it is still too dark you may need to calibrate your computer monitor.
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Old March 31st, 2003, 12:31 PM   #5
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It looks pretty contrasty on TVs. I should use the calibration method that Ken recommended?

The guy had a PC, both his laptop and home PC
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Old March 31st, 2003, 12:44 PM   #6
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That's a good starting point. Once your monitor is semi calibrated redo a little of your program and check it on a TV. It won't match exactly, but it should be close.
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Old March 31st, 2003, 12:48 PM   #7
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OKay, I give up. Neither my computer monitor or the cheapo TV even have the right aspects to adjust that the tutorial talks about. My TV has no contrast control, and my computer monitor has no chroma control. Oh well.

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Old April 1st, 2003, 03:47 AM   #8
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Joss, I have never seen a TV without a constrast control and I don't think yours is either. It is probably just labeled something else.

Brightness is sometimes called "black level" (which is actually more correct)

Chroma is often called "tint" or "hue"

I cannot at the top of my head think of other names for "contrast", but it should be the one that is not brightness.

If you can find a control, that will distort white lines and cause white areas to "bloom" - ie. expand when you turn it up to maximum, you found your contrast control.

Hope that helps

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Old April 1st, 2003, 04:38 AM   #9
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In regards to my Cheapo TV,

Yeah, that would be the "picture" control. But contrast, to me, means that it simultaneously affects your darks and your lights in the picture. When Contrast is turned all the way down, you should have a very narrow range of tones, no extreme darks or lights. When up, you should have deep blacks and blown out whites. I don't feel like it's doing that when I adjust this "picture" function.

Also, one of the instructions in that tutorial says to "turn your contrast all the way up, and then turn it down until the whites just start to respond." I took that to mean that past a certain point, the whites won't get any more blown out, even though your contrast control will still be moving. On that "picture" function, this doesn't happen; the whites continue to change for the entire time that you can adjust it.

"Tint" on my TV seems to be what I would call Hue, and "color" is chroma (though even when all the way down, it's not black and white, just dull, but still colorized)
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Old April 1st, 2003, 08:09 AM   #10
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Yes, "brightness" and "contrast" are highly dependant of each other.

Personally I usually do it the other way round (inpired by the DVD "Video Essentials".

First I turn contrast down to a comfortable medium level.

Then I set "brightness" using the SMPTE test pattern, so that the "blacker than black" at the bottom right disappears, and the slightly lighter than black is visible.

Then I turn up contrast until I start to see "blooming".

Then I readjust brightness and contrast a couple of times until both are ok.

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Old April 1st, 2003, 01:07 PM   #11
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How do you know they're ok. Does anyone else know whether "picture" actually is contrast? I'm seriously considering get one of the $300 industrial monitors.


I can't seem to get my whites to bloom. Blooming is when the white starts to bleed over into the colors on either side of it and above, right?
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Old April 1st, 2003, 04:45 PM   #12
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First make sure any Auto Picture or similar control is turned off. It will not allow an extended adjustment of the various picture controls.
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Old April 1st, 2003, 05:33 PM   #13
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Well, I could ramble on for hours about this since I am also a projector "nerd" finetuning my CRT front projector for hours just for the fun of it, but I will try to come up with a simple explanation.

First off, as Jeff suggests, turn off anything called "auto picture", "ideal" etc. These are usually some standard settings, and are certainly not ideal in terms of your signal source.

Brightness basically sets the 0% threshold whereas contrast sets the 100%

If you know any mathematics this explanation might help:

A first degree polynomial function:

y=ax+b

b here is a constant that sets the "level" of the function. This corresponds to brightness. a sets the "steepness" of the function so this corresponds to contrast.

If you have no clue what I am talking about, just keep reading.

If you turn brightness all the way down, the picture should go very dark, since it really sets the level of black. If brightness is too low, all dark grey colors will disappear into black. If brightness is too high, even black areas will seem grey.

Contrast sets the upper level. You basically want as much contrast as possible without distorting the image. This corresponds to getting the most light output from your display device without distortion. The best test is making a white square next to a slightly grey square and a white vertical line (do it with paint shop pro and mix it into your NLE and display it on your monitor).

Turn up contrast slowly until either the white square starts to enlarge compared to the grey one (bloom) or the white line starts to bend. That will show you when you overapplied contrast.

I would really recommend either "Video Essentials" or "Avia" on DVD. They explain the matter very well, and come with excellent test pictures too. The difference in visual quality after you properly calibrate your display device can be quite stunning.

Hope I didn't scare you off...

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Old April 2nd, 2003, 05:27 AM   #14
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Okay, I tried the white square grey square white line test. I couldn't really tell if the white was overlapping the grey, but I could tell that even with the contrast all the way up, the white line did not bend (except at the top of the screen, and I think that's cause this really is a seriously crappy TV. It does that no matter what the contrast is set to). Is it possible I could turn the contrast all the way up and have it be correctly set?

As I said before, it's the same with the Video University test. The white section of the SEMPTE bars starts to darken the first time I turn down the contrast from its highest setting.
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Old April 2nd, 2003, 05:58 AM   #15
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A contrast that can be set to max without distorting the image would usually indicate a broken contrast control to me, but if you seriously see NO blooming or line distortion when at the max setting, then by all means leave it there.

Then just adjust black level afterwards to get correct blacks.

The thing you need to look for with the white and grey box is not so much if they overlap, but more when the white box starts to grow compared to the grey one. They should be the same size right?

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