Color Decoding Controls are required to accurately and independently adjust saturation and phase for each of the three primary color channels (red, green and blue).
Color decoding consists of completely
recovering the red, green and blue color channels from a non-RGB
format, such as S-Video, composite video or component video, and then
processing them for correct RGB color response.
All color decoders are built upon a foundation of the saturation (color) and phase (tint or hue)
controls, which simultaneously alter the response of all three color
channels. In most cases, a color decoder is initially adjusted for the
blue color channel, using the color and tint controls that are found in the user menu, or sometimes in the display's service menu. Proper alignment of the red and green channels is also required, and to
achieve this, discrete saturation and phase controls are also
required for each of the red and green channels.
Full color decoding controls are required not only to properly calibrate the display but also to compensate for source errors.
Displays receiving bona fide RGB signals do not need to pass those
signals through color decoding circuitry. In addition, where a display
is receiving a true RGB video signal, there is no need for user-accessible
controls for adjusting color or tint, as the RGB signal should need no further adjustment. If an RGB signal is present on a display's selected input, and working
color and/or tint controls are provided via the user controls, this may be an
indication that the RGB signals are being converted to
some non-RGB format somewhere within the display's signal processing
Some displays provide user color controls that are significantly more
elaborate than the standard color and tint settings. Some of these are
labeled as “color decoder” controls, or their naming convention would
indicate that they can be used to eliminate all color errors. Despite
the seemingly consumer-friendly labels, in many cases these controls
are not proper color decoder controls and their use will not
necessarily improve color accuracy.
If you are in doubt about the specific benefits of a display's color
controls, contact an ISF Forum calibrator near you for more information.