Expert: Andre Hickman - 3/12/2007

Question
What it does ? why we should use it ? is it only looking purpose on our Computer Monitor or it effects our final output? what is its importance ?

Answer
Actually, I didn't even know what a LUT was...I had to look it up.  This is what I found:

Lookup table (LUT) The LUT is an essential feature of any system working with images of greater than 8bits/per channel. It allows such images to be displayed correctly on 8bit displays such as computer monitors and is also used to convert images between formats. A LUT describes exactly how a 16bit color value should be represented in 8bits and allows non-procedural, user-defined image conversions. It is particularly useful in converting logarithmic images (such as a film image in Cineon) to a linear image format. It also allows you to correctly display high-bit depth images on 8bit computer monitors without altering the original high bit-depth color information of the original film scan – a prerequisite for most high-quality film effect work.

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So unless you are converting from true film to 8-bit color, etc.  I doubt you will run across it much.