early Network color was not equal

[yagosaga]

Hi Pete,

Originally Posted by Pete Deksnis

Not sure what the exercise will demonstrate.

This file has 100% saturated colors and 100% white. The reference color bars usually have 75% saturated colors due to the fact that the amplidute of the red signal might be overloaded with 100% saturated color. So, with this file you can test whether the RGB drive is proper operating. (If the tubes are tested good on your CT-100, it should operate properly.)

Take a 'perfect' or reference color bar (as you have provided) and reproduce it on an sRGB TV or monitor driven via component or DVI or HDMI, and you get a 'perfect' (okay, really, really good) color bar image. I've done that and photographed the sRGB-phosphors screen with an sRGB digital camera and generated an sRGB color space jpg. It can be seen here.

For comparison: I have displayed the color bars on my computer monitor, and photographed it. See the file in the attachment. You can see that there is a bias toward blue in the green, but the other colors seems to be OK (within a large range of standard error). Now you can compare the monitor screenshot with the screenshot of the 21AXP22A.

That same reference color bar signal turned into an NTSC signal by a DVD player [and either modulated or directly introduced into the first video amplifier (which is the way I do it)] is going to be corrupted or at least constrained by the NTSC system and the DVD-player version of NTSC. I think I would see what I see now since the color bar pattern on my DVD is essentially reference quality before it takes the long NTSC route to my 15GP22 screen, and as I have noted above, the brightness/contrast range is already adjusted correctly as shown on a screen shot earlier.

I feed the video signal as R.F. signal directly into the tuner of the CTC5. So I get a nearly perfect impression about the disadjustments and the losses in the color channel up to the screen of the 21AXP22A. (Note that I have to convert the PAL signal into NTSC which means an additional loss of signal quality, especially in the transit between magenta and green.)

There is another factor not yet mentioned -- that of high-voltage. Your CTC5 has what, 25 kV to play with and the regulator is far better than the 6BD4 circuit used in the CT-100.

High voltage in the CTC5 is 19.5 kV according to the manual, and I have controlled it.

I believe that your CT-100 has a much better color performance than it is shown here in your demonstrations, and this is what I want to prove with these tests. When I got the CTC5, I misadjusted color and brightness a lot of times before I understood how it works. I did only know the PAL tv sets, and they are working different.

- Eckhard

[old_tv_nut]

100% amplitude bars are NOT good for playing through a RF modulator. The NTSC system (and PAL) are designed to overmodulate the yellow and cyan bars in this case, since such full amplitude colors are almost never encountered in natural scenes.

The 75% bars are not 75% saturated, they are 100% saturated, but 75% amplitude. However, they are usually set next to a 100% white bar, which makes all of them look darker by comparison. When this pattern is used, it happens that the yellow bar chroma peaks equal the amplitude of the 100% white bar, so it is safe from overmodulation.

The picture posted by Pete is actually quite good, just the white balance and exposure of the still camera is off. I have attached an adjusted copy, which should be much closer to the visual effect in person.

[yagosaga]

Originally Posted by old_tv_nut

The 75% bars are not 75% saturated, they are 100% saturated, but 75% amplitude. However, they are usually set next to a 100% white bar, which makes all of them look darker by comparison. When this pattern is used, it happens that the yellow bar chroma peaks equal the amplitude of the 100% white bar, so it is safe from overmodulation.

Thank you very much for this correction!

The picture posted by Pete is actually quite good, just the white balance and exposure of the still camera is off. I have attached an adjusted copy, which should be much closer to the visual effect in person.

This picture with adjusted white balance does reveal what the the visual effect in person on a CT100 might be.

Here is a link to color bars on a 15GP22 which looks similar to your adjusted copy:

http://bs.cyty.com/menschen/e-etzold...5inBetrieb.jpg

- Eckhard