I have looked at the DVE HD "GREEN" stair step pattern and have clipping at the 95 db and above.

However when I look at the DVE HD "GRAY" stair step pattern (I have a front CRT projector and can turn off blue and red guns to leave Green on) I see no clipping.

Shouldn’t these two patterns show identical?

Is the DVE HD "GREEN" stair step pattern somehow different? Maybe recorded at higher levels?????

Which would be the correct to look at in regards to clipping green?

They won't necessarily be the same, Frank. Remember that gray also includes blue and red as well as green. If red or blue is high enough to make up the difference in luminance at those levels, you won't see clipping on the gray patterns. But a meter will show the reduced green that your eyes may not see.

So if I am showing a bit of clipping on the high ire end using the "Green" DVE HD stair step pattern then should I reduce the green via my Lumagen HDP?

They won't necessarily be the same, Frank. Remember that gray also includes blue and red as well as green. If red or blue is high enough to make up the difference in luminance at those levels, you won't see clipping on the gray patterns. But a meter will show the reduced green that your eyes may not see.

Royce, what you wrote is certainly true as a general observation, and I prefer using a meter, but Frank wrote that he was using the gray pattern with the red and blue guns turned off. With no red or blue component, one would think that the green would appear the same in the two patterns.

Without a meter, it's hard to guess what is happening.

Does the projector have a color management system, where you can tune the primary colors? Did you leave the red and blue guns on when displaying the green stair step pattern? If both are true, perhaps your green color is fine tuned by adding a little red and blue, so your green stair step pattern actually has a little bit of red and blue, and the gray pattern with red/blue guns turned off is showing you the green gun alone.

Royce, what you wrote is certainly true as a general observation, and I prefer using a meter, but Frank wrote that he was using the gray pattern with the red and blue guns turned off. With no red or blue component, one would think that the green would appear the same in the two patterns.

Without a meter, it's hard to guess what is happening.

Does the projector have a color management system, where you can tune the primary colors? Did you leave the red and blue guns on when displaying the green stair step pattern? If both are true, perhaps your green color is fine tuned by adding a little red and blue, so your green stair step pattern actually has a little bit of red and blue, and the gray pattern with red/blue guns turned off is showing you the green gun alone.

Ah. I didn't read it that way. My bad. His color decoder is probably contributing to the clipping on the green stairstep pattern, either with addition of red and blue as you said, or with a bit of green push. Frank, try taking color to zero while looking at the green stairstep. If the clipping fades away as you reduce color, you'll know it's from the color decoding.

Is the DVE HD "GREEN" stair step pattern somehow different?

Yep, it is different.

Look at video as a signal that is made up of 2 signals, black-and-white information (called luma) and color-information (called chroma). Both are needed to get a color picture.

The gray ramp only shows you the "range" of the luma part of the video signal.
The green ramp shows you the "range" of the chroma (+luma) part of the video signal.

In other words, the chroma part is clipped somewhere in your system. And as "Rolls-Royce" pointed out, lowering the "Color"-control(s), which essentially lowers the chroma-level/amplitude, might help you found out where/when the clipping occurs.

Does the projector have a color management system, where you can tune the primary colors? Did you leave the red and blue guns on when displaying the green stair step pattern? If both are true, perhaps your green color is fine tuned by adding a little red and blue, so your green stair step pattern actually has a little bit of red and blue, and the gray pattern with red/blue guns turned off is showing you the green gun alone.

The equipment I am using is a Toshiba XA2 HD DVD player outputting 1080p24 into a Lumagen HDP video processor that in turn outputs 1080p60 into a Sony G90 CRT front projector.

My G90 does not have a color management system but my Lumagen HDP does.

When I displayed the "GREEN" DVE HD stair step pattern I did not turn blue and red off as I assumed it only lit up the green gun on the projector.

I am not shure what you mean when you talk about adding a bit of red and blue? How would that help with my Green clipping?

Ah. I didn't read it that way. My bad. His color decoder is probably contributing to the clipping on the green stairstep pattern, either with addition of red and blue as you said, or with a bit of green push. Frank, try taking color to zero while looking at the green stairstep. If the clipping fades away as you reduce color, you'll know it's from the color decoding.

Ok.

In my Lumagen I used the green off set control to reduce the green color and I was able to remove the green clipping.

I believe my Toshiba XA2 HD DVD player is outputting RGB 444 into the Lumagen HDP video processor. Does that mean that perhaps my XA2 is causing the problem with its color decoder?

Yep, it is different.

Look at video as a signal that is made up of 2 signals, black-and-white information (called luma) and color-information (called chroma). Both are needed to get a color picture.

The gray ramp only shows you the "range" of the luma part of the video signal.
The green ramp shows you the "range" of the chroma (+luma) part of the video signal.

In other words, the chroma part is clipped somewhere in your system. And as "Rolls-Royce" pointed out, lowering the "Color"-control(s), which essentially lowers the chroma-level/amplitude, might help you found out where/when the clipping occurs.

Thanks for detailed explanation on the difference between the two patterns.

So basically, since no one is saying that the "GREEN" DVE HD stair step pattern is off/wrong than I should assume that the green stair step pattern is correct and I should use it to adjust my green color (to avoid green clipping)?

Is there any other patterns that I could use to check my green clipping using my Toshiba HD DVD player?

Yes, the pattern is correct.

use it to adjust my green color (to avoid green clipping)?
Use the pattern yes. However, it is likely that the clipping has occured in the display or in the source and it might be a good idea to examine if you can remove the clipping by using controls in those components.

Is there any other patterns that I could use to check my green clipping using my Toshiba HD DVD player?
Double check with the basic Color-decoder pattern (the one DVE tells you to use for the Color-control and the color-filters) so that you haven't destroyed the picture even more, sometimes a compromise is needed (in other words, make sure that you don't mess up your picture somewhere else in order to get the entire green chroma range).

I mean, it is easy to create worse problems than some "green chroma clipping" above 95%. ;)

(by the way, the Color-decoder pattern is made up of 75% "sampels" from the R,G,B,C,M and Y Color-ramps while the white background is a sample of the 75% part in the Gray-ramp. To give you an idea how the different patterns are connected...you could say that the ramps are a "Super Color Decoder Checker" :))

BTW, Frank, using cuts and drives whether in the source, processor, or display, is not the way to fix color decoder (chroma) errors. A lot of folks claim they took care of red or green push in that manner, but they are only doing bad things to their grayscales by doing so. Instead, if your Lumagen has CMS controls, you should be able to reduce green saturation in that menu.

I think all Lumagen processors has a "Green Chroma"-level control, nice feature.