UMBC High Performance Computing Facility
Color Differencing Structural Similarity Index Metric
(CD-SSIM)
Marc Olano and Wesley Griffin, CSEE Department of Computer Science and Electrical Engineering
While grayscale image quality assessment is well-understood, color
image quality assessment remains an open research problem. For many
applications, using a grayscale image quality metric is sufficient and
there are excellent existing algorithms. There are cases, however, when
color information must be considered for image quality. One such
application is texture compression. Modern image compression methods
leverage the sensitivity of the human visual subsystem to vary the
compression of the luminance and chrominance components of an image. A
modern compression algorithm could use an image quality metric to drive
compression rates, but if the metric does not handle color, then the
chrominance components would be heavily compressed, compromising
quality.
There are several existing algorithms for color image quality
assessment. These algorithms tend to be complex and use Contrast
Sensitivity Functions to model the sensitivity of the Human Visual
System (HVS). Recent advances in grayscale image quality assessment have
resulted in very simple formulations for image quality. These
``top-down'' approaches attempt to simulate the HVS response instead of
modeling the HVS. One such approach is the Structural Similarity Index
Metric (SSIM). Extending SSIM to work with color would provide
applications with a simple but accurate color image quality metric. We
present a new algorithm that combines SSIM with CIELAB color
differencing to perform objective image quality assessment on color
images.