There are many instances in conversion where there is not an easily definable relationship between variable and transducer output, and it may be difficult or impossible to write a best fit equation that is adequate for linearization of the variable.
In this case, lookup tables are used.
The tables correlate transducer output to the true value of the variable, and these values are stored in memory.
The processor can retrieve the true value of the variable from the transducer and temperature reading by consulting its lookup tables. This method is extensively used, for instance, with thermocouples.