It could be difficult. Light intensity varies a huge amount between "enough light that you don't bump into the furniture" and full sunlight. I think that you are looking at a 1000:1 or 10000:1 ratio.
The result of that could be that you need to work with 16 bit or longer numbers.
A lookup table is used where there is no easy mathematical relation between the input and output of a function. You just have a big table of values. If the input to the function is n, the output is just the nth entry in the table.
However you need to be able to write the table, and I can't help you with that. Do you have any exact measure of what you want the LED to do in a particular lighting condition?
Also, if you have a very wide range of input values, the table could become too big to handle. You don't say what you are writing the programme on. If it is a PC, a couple of MB of table is not a problem. On a microcontroller you have to be more subtle.