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Old 29th January 2004, 20:09   #1  |  Link
trevlac
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Preview on PC vs TV

Has anyone been able to get the colors on their PC to look reasonably close to a standard TV?

I measure the gamma on my TV (at factory settings) to be about 1.6. This is probably due to the black level being cranked up. I can change alot on my monitor, and I should be able to get reasonably close to my TV settings (excpt maybe sharpness and interlace).

Has anyone ever tried to adjust their monitor to match a TV?

Should I just buy a studio monitor?
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Old 20th February 2004, 03:58   #2  |  Link
rfmmars
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It can't be done. With NTSC the R-Y resolution is only 60 line and the B-Y channel is only 40 lines, now thats not per inch, but horizontal width of the screen. Pal is less. There is no G-y but it is made by decoding analog and combined with the detail comes from black&white signal. Here is where PAL is better, British PAL being best.

The color phousphors are different in the CRTs. This is why you must have a analog monitor connected to your PC to do color and gamma adjustments.

Richard
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Old 20th February 2004, 17:35   #3  |  Link
trevlac
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Quote:
Originally posted by rfmmars
It can't be done.

....

The color phousphors are different in the CRTs. This is why you must have a analog monitor connected to your PC to do color and gamma adjustments.
Thanks for your comments. Since I posted, I have done a bit of reading. It can't be done is the general answer. However, this never seemed to jive with the fact that there are a bunch of different display types out there (especially with HD). Also, it is not clear that the phosphers are truely different.

Here is the most ligit discussion of this I have found so far.

This is a piece of it in response to makeing a combo TV/PC monitor.
Quote:
It's possible, and has been done (for instance, Toshiba has one product and offerings from other companies are available or are on the way). But such designs ARE compromises, and won't give the best performance possible in either application.

There is a fundamental difference between CRTs designed for TV use,
and those used in computer monitors. It's a brightness/resolution
tradeoff - TV tubes are run about 3X or so the brightness of a typical
computer monitor, but sacrifice the ability to use small spot sizes
and fine dot pitches to do this. You don't see very many color tubes
running at 100 - 150 fL brightness and still using an 0.28 mm pitch!
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Old 21st February 2004, 00:50   #4  |  Link
rfmmars
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Also the standards vary between CRT manufactures, plus the demodulation is not standard. It's suppose to be 90 degrees, but that doesn't allow for good shin tones, so most demodulate somewhere between 105 ~ 110 degrees, which reduces the need to adjust the (TINT-HUE) control with a trade off or very orangie reds. Same thinf in PAL where there is no hue-tint control.

So broadcast moitors are great to use because the P22 phospher is exact and demodulion angle is 90' It would be great if these were easy to obtain.

But I still use those 15 year old Commadore S-Video monitors

Richard

Last edited by rfmmars; 21st February 2004 at 01:36.
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Old 23rd February 2004, 22:07   #5  |  Link
trevlac
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Thanks again...

So ...


A standard TV does not look like a NTSC monitor (not same phosphers and hue is off, color temp is different, etc) ?

A PC CRT does not look like a NTSC monitor because of interlace, sharpness, color temp, brightness? It looks like you can get PC monitors with P22 and color temp controls. I'm sitting at a compaq with 9300, 6500, 5500 temp controls. Not sure about the phosphers.

I Assume one wants to do color correction on an NTSC monitor because it matches a standard, whereas a TV and PC monitor do not match a standard (unless you know the specs of a given PC monitor).

So the point is the adjust to a standard not to a subjectively 'good' picture.
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Old 24th February 2004, 01:42   #6  |  Link
rfmmars
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Hold on...... I think I confused you a little. Yes you could use a TV set as a monitor, but if you could get one of those older 14" Commadore monitors, they have a very sharp trace, perfect white balance and gamma tracking, and s-video in with audio.

A studio monitor will have exact P22 phosphers that are set down in NTSC standards.

You can adjust your PC monitor for the correct tempeture, but you are dealing with computer RGB, not NTSC R-y B-y.

I been around for a long time in this business, and back in 1954 the first color TVs RCA CTC100 gave a very precicse color rendering, but the lights almost had to be turned off in the room.

Over the years the CRTs were made brighter, but tv companies wanted to make it so you didn't have to adjuct the hue control for each program. So what they did was to increse the demodulation angle from 90 degrees to somewhere around 110 degrees, so no longer do we see that deep red color. Only onprojection set do they come close.

On your CPU monitor set it somewhere between 5600 and 6500 K

A tv that has a video in is better than trying to balance on a computer monitor. The standars are pretty loose. What I do is play several commercial DVDs and set the controls for best picture, and that is my working standard.

Richard
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Old 24th February 2004, 21:36   #7  |  Link
trevlac
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Quote:
Originally posted by rfmmars
A studio monitor will have exact P22 phosphers that are set down in NTSC standards.
So a studio monitor is best because it follows the standard, and it should be of reasonable quality.

Quote:
You can adjust your PC monitor for the correct tempeture, but you are dealing with computer RGB, not NTSC R-y B-y.
Well, I can also adjust the source can't I? I mean, I can run the rgb values thru some calculations as YIQ clip them, adjust for black/white range ... blah blah blah, before I display them. I guess I could never keep super black and super white, but I'm not clear why this is a problem.

Quote:
A tv that has a video in is better than trying to balance on a computer monitor. The standars are pretty loose. What I do is play several commercial DVDs and set the controls for best picture, and that is my working standard.
Sounds like a good method... use commercial DVDs to see a standard 'look' and then shoot for that. Nice and simple. Better results if you have better equipment, but should work on most (reasonably adjusted) equipment.

--------------------
I really do appreciate this discussion. I am trying to learn the topic of color correction. I've written a vdub plugin that shows me histo/wfm/'hot pixels'/ and working on vectorscope. Past 'flying by instruments', I am also trying to get a handle on how I can tweek by eye. I think the commodore tip was great. I'm now looking for one.

I need to get past learning/coding into more seeing and doing. Comming up with a reasonable viewing method has been holding me back.

Thanks
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Old 6th March 2004, 09:07   #8  |  Link
morsa
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It could be perfectly done.Matrox Parhelia comes with an utility to adjust the PC monitor to look just exactly as a video monitor (talking about gamma and colours).
The problem is you would have to deal with a lot of specs from the video monitor and from you PC monitor and then make a color profile or make your own customized LUT to get the result.
It is much the same Kodak does for its Digital Intermediate systems, which use normal PC monitor that after using the correct color profiles give you exactly the same look as positive projection copy.
Anothe item to take note is that colors not only change because of the PC monitor but also the video card you are using, so your LUTs will depend on the combination of these two things.
Hope this helps.


BTW, I've been using LCD monitors to check the video in a feature film recorded in DV ( for going to 35mm) and they work perfectly.
The so called studio monitor aren't so standard as they say.Take two from different manufacturers and you'll see what I'm saying.

Last edited by morsa; 6th March 2004 at 09:10.
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Old 9th March 2004, 22:42   #9  |  Link
trevlac
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@morsa

Thanks for the comments. It sounds like it is doable, but probably not worth it. I imagine, you would have to have a colorimeter type of device to really match monitors. I expect this is what studios use.

I found the best practical advise to be to use a set of commercial DVDs as a standard and match to them.

Do you think this would work? I mean, matching gamma and hue/saturation buy viewing select commercial scenes and my work on a reasonable quality CRT PC monitor.
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Old 10th March 2004, 02:46   #10  |  Link
morsa
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Not exactly.It would be better to take a color rendition chart, measure the values for each of their colors, make a version for video with the standard you are going to use (CCIR 601 or 709)and only then compare the two images and try to calibrate acordingly.
BTW I still believe it would be a better way to make a custom lookup table, I mean I guess it is the only suitable solution.
If you have seen an LCD projector, may be you have noticed I has a really bad yellow color rendition, that is correctible with a lookup table, cause you can take just the yellow range and add a little bit of red without changing any other color.

About the DVD way, yes it would be right mostly for the gamma and saturation part, but it won't work correctly for the color balance.
You will end up with many differences between some selected color aside you could match gamma characteristics.
The same happens with photographic film.
For example your digital image has a nice light blue and may be other colors.You record it to film and ,what happens? You discover your nice light blue is now many times darker than your original and other colors are exactly the same as they were in the digital master, why?
Because film acts different for every color regardless of its luminance.The same happens between every CRT tube.
When you use a professional color calibration system what you get is a software that will give you a lookuptable that compensates your output image for every color.

Last edited by morsa; 10th March 2004 at 02:56.
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