Dematrix

The dematrix (also called matrix for short ) is a special circuit in a color television that works with one of the analogue color transmission systems NTSC , PAL and  SECAM .

In these color transmission systems, only the following are transmitted within the framework of the YUV color model :

• the black and white  signal Y for the brightness as well
• the color type and color strength information:
  • U (BY) for the color blue and
  • V (RY) for the color red;

the color green is not transmitted, it is already contained in the black and white signal.

With the help of the dematrix, the following signals are recovered from the transmitted television signals by adding and subtracting them so that they can be fed to the color picture tube :

• in the color difference concept the three color difference signals BY, RY and GY
• in the RGB concept the primary color signals red, green and blue.

In the early days of color television technology, the difference was formed in the picture tube by feeding the Y signal to the common grid and the color difference signals U and V to the cathodes for blue and red. However, this resulted in a difficult brightness and contrast setting.

At the latest, the SCART - RGB connection then required dematrix.