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ThomasL · 03-28-2002, 09:51 AM

What are these terms Color Decoder, Red Push, Grayscale and why is everyone sunburned?

If you hang around the tv section of the forum, you'll invariably hear the terms "color decoder", "red push" and "grayscale" mentioned.

The tv's color decoder, in simplistic terms, is the circuitry and logic that determines how colors look on your television.

Grayscale is the term used to define how grays (from white to black) look on your set. Think of your tv's grayscale as the underlying canvas onto which color is then added by the color decoder to form a complete colorized picture. A tv's grayscale is often measured in terms of temperature.

You will hear people refer to the "color temperature" of their set or your set may have a "color temperature" setting such as cool, neutral, and warm. Without getting into what this is actually measuring, it is important from a user's perspective to know that cool means a more blueish grayscale (and in fact a hotter color temperature!) while warm is the opposite end and produces a more reddish grayscale (and it follows a cooler color temperature).

Movie makers have a standard that they adhere to called NTSC D6500K. This is the color temperature that they use when putting together the dvd since it is the standard color temperature for the American tv standard. This is the color temperature that, in theory, all tvs should have, but almost always this is not the case.

Most tv manufacturers don't adhere to this because D6500K is a relatively low color temperature that produces a grayscale that doesn't stand up under showroom lights. Because of this and the fact that companies want their sets to stand out against the competition, they set the tv's color temperature so it is very blue along with a contrast setting usually at maximum. This usually produces a crisp bright picture on the showroom floor but also produces fleshtones that don't look realistic.

This is where "red-push" comes into play. To counteract the "blueness" of the grayscale, manufacturers then tell their color decoders to over-emphasize red. This allows them to continue having a high contrast, bright set as well as fleshtones that seem to look good. Once you get the set home and out of the showroom lights though, and turn the contrast down to reaonable levels, it is then you'll notice that everyone looks sunburned.

So, what can you do about this?

Well, firstly, you should get a calibration disc such as Avia or Video Essentials which will allow you properly calibrate your tv's basic settings - brightness, contrast, color, hue and sharpness.

Once that is done, there are a few things one can do to correct the overly blue grayscale and the red push problem.

First, if your set has a color temperature setting, change it to 'warm' or perhaps 'NTSC standard' if your set has that option. This still may not be close to D6500K but it is most likely better than the default. Next, use your calibration disc to determine how much red push you have. Avia has a nice color decoder pattern that will allow you to quantify this.

At this point, adjust the color control downward until the red push is below 10 percent. This will de-emphasize red as well as the other colors too, so it is a compromise. You will be taking away all colors a little in hopes that the overemphasized red will not be so distracting.

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03-28-2002, 09:51 AM
ThomasL Member Join Date: Mar 2001 Local Time: 08:31 AM Local Date: 07-09-2008 Posts: 1,013	What are these terms Color Decoder, Red Push, Grayscale and why is everyone sunburned? If you hang around the tv section of the forum, you'll invariably hear the terms "color decoder", "red push" and "grayscale" mentioned. The tv's color decoder, in simplistic terms, is the circuitry and logic that determines how colors look on your television. Grayscale is the term used to define how grays (from white to black) look on your set. Think of your tv's grayscale as the underlying canvas onto which color is then added by the color decoder to form a complete colorized picture. A tv's grayscale is often measured in terms of temperature. You will hear people refer to the "color temperature" of their set or your set may have a "color temperature" setting such as cool, neutral, and warm. Without getting into what this is actually measuring, it is important from a user's perspective to know that cool means a more blueish grayscale (and in fact a hotter color temperature!) while warm is the opposite end and produces a more reddish grayscale (and it follows a cooler color temperature). Movie makers have a standard that they adhere to called NTSC D6500K. This is the color temperature that they use when putting together the dvd since it is the standard color temperature for the American tv standard. This is the color temperature that, in theory, all tvs should have, but almost always this is not the case. Most tv manufacturers don't adhere to this because D6500K is a relatively low color temperature that produces a grayscale that doesn't stand up under showroom lights. Because of this and the fact that companies want their sets to stand out against the competition, they set the tv's color temperature so it is very blue along with a contrast setting usually at maximum. This usually produces a crisp bright picture on the showroom floor but also produces fleshtones that don't look realistic. This is where "red-push" comes into play. To counteract the "blueness" of the grayscale, manufacturers then tell their color decoders to over-emphasize red. This allows them to continue having a high contrast, bright set as well as fleshtones that seem to look good. Once you get the set home and out of the showroom lights though, and turn the contrast down to reaonable levels, it is then you'll notice that everyone looks sunburned. So, what can you do about this? Well, firstly, you should get a calibration disc such as Avia or Video Essentials which will allow you properly calibrate your tv's basic settings - brightness, contrast, color, hue and sharpness. Once that is done, there are a few things one can do to correct the overly blue grayscale and the red push problem. First, if your set has a color temperature setting, change it to 'warm' or perhaps 'NTSC standard' if your set has that option. This still may not be close to D6500K but it is most likely better than the default. Next, use your calibration disc to determine how much red push you have. Avia has a nice color decoder pattern that will allow you to quantify this. At this point, adjust the color control downward until the red push is below 10 percent. This will de-emphasize red as well as the other colors too, so it is a compromise. You will be taking away all colors a little in hopes that the overemphasized red will not be so distracting.