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These memories constitute the look-up table for the converting
into false colour the 16 levels of grey.
The output of the RAM is converted in analogic form by the
blocks 9, 10, 11 giving the levels of the three basic colours: RED,
GREEN, BLU.
Block 12 has the function of making these signals compatible
with the TV colour set operating characteristics.
With this system it is possible to change the false colour
coding, by changing, with an appropriate program, the content of
the RAM.
System in fig. 2
In this system the functions of the blocks 1 to 5 are the same
as the ones described in the previous system.
Here the RAM's are used as support functions for the false
colour coding.
The RAM output data (previously addressed by the ADC output)
are now decoded by the 9, 10, 11 blocks which, in turn, address a
single switch for each input combination.
This operation enables the transfer of the SCM (level of grey)
luminance signal properly weighed. The weights are constituted by
high precision resistive dividers. The design and values of these
dividers fix the resolution capability of the image representation
in false colour, together with the scale of distribution of its
tonality.
The switch output are de-multiplexed by using three operational
circuits, hence they are combined by the colour encoder, whose
output is the video signal which drives the TV display screen.
12° July 1978