  Color in an image is resolved into 3 or 4 color components and 2-Dimages of
these components are stored in separate channels. Most of the color image
enhancement algorithms are applied channel-by-channel on each image. But such a
system of color image processing is not processing the original color. When a
color image is represented as a quaternion image, processing is done in
original colors. This paper proposes an implementation of the quaternion
approach of enhancement algorithm for enhancing color images and is referred as
the modified alpha-rooting by the two-dimensional quaternion discrete Fourier
transform (2-D QDFT). Enhancement results of this proposed method are compared
with the channel-by-channel image enhancement by the 2-D DFT. Enhancements in
color images are quantitatively measured by the color enhancement measure
estimation (CEME), which allows for selecting optimum parameters for processing
by the genetic algorithm. Enhancement of color images by the quaternion based
method allows for obtaining images which are closer to the genuine
representation of the real original color.
