A real-time color mapping system includes a memory and a converting module. The memory is configured for storing a mapping table. The converting module is configured for reading the mapping table stored in the memory, and for converting first image grayscale values corresponding to a first image signal into second image grayscale values corresponding to a second image signal according to the mapping table. The converting module utilizes at least part of bits corresponding to each of the first image grayscale values as a memory address to look up in the mapping table, thereby converting the first image grayscale values into the second image grayscale values. A real-time color mapping method is provided herein as well.