TDA9178

   The TDA9178 is a transparent analog video processor with YUV input and output interfaces. It offers three main functions: luminance vector processing, colour vector processing and spectral processing. Beside these three main functions, there are some additional functions. In the luminance vector processor, the luminance transfer function is controlled in a non-linear way by the distribution, in 5 discrete histogram sections, of the luminance values measured in a picture. As a result, the contrast ratio of the most important parts of the scene will be improved. Black restoration is available in the event of a set-up in the luminance signal.
   A variable gamma function, after the histogram conversion, offers the possibilities of alternative brightness control or factory adjustment of the picture tube. An embedded 6-bit ADC can be used for interfacing three analog low frequency voltage signals (e.g. ambient light control or beam current voltage level) to the I2C-bus.
   The adaptive black stretch function of the TDA9178 offers the possibility of having a larger 'weight' for the black parts of the video signal; the white stretch function offers an additional overall gain for increased light production. To maintain a proper colour reproduction, the saturation of the U- and V-colour difference signals is also controlled as a function of the actual non-linearity in the luminance channel.