What is the primary point processing technique that uses a look-up table to enhance contrast?

The primary point processing technique that uses a look-up table to enhance contrast is gray-level mapping. This technique involves the application of a transformation function defined in a look-up table that modifies the pixel values in an image. The purpose of gray-level mapping is to remap the original gray levels into a new range of values, which enhances the visual contrast of the image. By adjusting the gray-level distribution, the technique can make certain features of the image more prominent, improving the overall interpretability of the data.

In contrast, histogram equalization focuses on adjusting the image contrast by redistributing the intensity values according to their frequency distribution. This method aims to create a uniform histogram rather than simply remapping pixel values based on a pre-defined look-up table.

Image filtering entails the application of various algorithms and operations to smooth or enhance details in the image, but it does not specifically use a look-up table for contrast enhancement.

Spatial frequency filtering deals with enhancing or suppressing specific frequencies in the image, which influences sharpness or blurriness but does not directly involve a look-up table like gray-level mapping does.

Therefore, gray-level mapping is the most suitable choice among the options for its specific use of a look-up table to enhance contrast effectively.