What exactly is the color decoder and how is it checked/adjusted?

Is there a realtionship between gray scale tracking and accurate color decoding?

I have a Panny 9UK plasma, it it matters.


thx

bob

It's the display's ability to properly convert YPbBr (or other color spaces) to RGB.

You can check it with the Avia calibration disc. Look at the Blue color bar though a blue filter, red color bar with the red filter and the green color bar with the green filter. If they all look good, then your color decoding is good. If only blue looks good (because you use this to set color/tint), but red and/or green do not, then you have a color decoding problem. Some sets have a way to adjust color decoding. Most don't.

No, there's no straightforward relationship between gray scale tacking and color temp. One can be perfect while the other is screwed up.

No, there's no straightforward relationship between gray scale tacking and color temp. One can be perfect while the other is screwed up.

:confused:
I think you mistyped.

There is no relationship between color decoding and greyscale/color temperature.

Greyscale= color temperature, so certainly there is a relationship there because the two things are synonomous.

So, what would be the symptoms of a "bad" decoder with excellent gray scale?


thx

bob

Imperfect/incorrect colors. Most commonly mentioned is "red push" which is often intentionally implemented by the manufacturer to compensate for the intentionally high color temperature (which makes the picture look brighter, which sells TVs).

With a high color temperature and accurate color decoding, skin tones would look rather sickly, so they "push" up the red channel to try to compensate. This is what leads to the orange/sunburned skin look....what I call the "TV look".

:confused:
I think you mistyped.

There is no relationship between color decoding and greyscale/color temperature.

Greyscale= color temperature, so certainly there is a relationship there because the two things are synonomous.Whoops, yes, this was a case of vapor lock. I meant to say that there's no straightforward relationship between color decoding and color temp. Sorry.

Imperfect/incorrect colors. Most commonly mentioned is "red push" which is often intentionally implemented by the manufacturer to compensate for the intentionally high color temperature (which makes the picture look brighter, which sells TVs).

With a high color temperature and accurate color decoding, skin tones would look rather sickly, so they "push" up the red channel to try to compensate. This is what leads to the orange/sunburned skin look....what I call the "TV look".


I seem to notice "sickly" skin tones more on warm setting than cool. For regular TV watching, I can't use warm because of this. On a good DVD, warm looks like it does at the show :)


bob

I seem to notice "sickly" skin tones more on warm setting than cool. For regular TV watching, I can't use warm because of this. On a good DVD, warm looks like it does at the showColor temperature presets like Warm are rarely accurate. You really need custom color temperature controls and the means to measure their results.

Bob,
FYI, broadcast SDTV isn't a good source for judging PQ. In my area, it varies widely from awful to not so awful, but rarely great.

-Steve

Your television image is a black and white image with color applied to it.

Grayscale is the ratio of RGB levels that your TV uses to draw the black and white image. I think of it as the shade of the paper on which the color image is drawn. If the paper isn't the right shade, all the colors applied to it will be off.

The color decoder is that part on the TV that decides the ratio of RGB values and their intensity to be used to draw the color part of the image. It controls what kind and how much paint is applied to the paper. If it's off the colors won't be correct either.

It's the display's ability to properly convert YPbBr (or other color spaces) to RGB.

You can check it with the Avia calibration disc. Look at the Blue color bar though a blue filter, red color bar with the red filter and the green color bar with the green filter. If they all look good, then your color decoding is good. If only blue looks good (because you use this to set color/tint), but red and/or green do not, then you have a color decoding problem. Some sets have a way to adjust color decoding. Most don't.

No, there's no straightforward relationship between gray scale tacking and color temp. One can be perfect while the other is screwed up.


Sorry to be so naive, but what are you looking for with the filters?

Is this how the ISF guys check the decoder, too?

thx

bob

The disc explains the process clearly. Basically, what you are looking for is equal levels of intensity between different patches of color. It's hard to explain, but its easy to understand with the examples the disc provides.

Bob,
The colored filters are used to isolate the individual primary colors (red, green and blue) of the display. When viewing a standard color bars pattern through a filter, the color decoding is set correctly when the amount (intensity) of a given primary color is the same for gray and each of the secondary colors containing that primary. For example, when viewing the standard color bars pattern through a blue filter, the intensity of blue seen through the filter should be the same for the blue, gray, cyan and magenta bars. Likewise, using the red filter, the intensity of red seen through the filter should be the same for the red, gray, yellow and magenta bars.

With a properly designed color decoder, it should only be necessary to adjust the tint and color controls using one of the primary colors; the other two should also then be correct, however, this is ofeten not the case. Under these circumsatances, the color decoder needs to be adjusted (if possible) in the service menu using teh axis controls. This is not something that is usually necessary on Panasonic plasmas, they have very good color decoding.

As stated previously, the most likely cause of the problems that you are seeing is an inaccurate gray scale, which is not directly related to color decoding.

-Steve

Thanks, guys

I have GetGray and Scott is sending the filters. Next week I will be attempting gray scale adjusting with GetGray/ Eyeone Display LT/HCFR. 3 of us in the bay area are part of a round robin using another members' sensor.

Appreciate all your help :)


bob