Welcome to METACOW, The source for all your METACOW needs.
Mark D. Fairchild & Garrett M. Johnson
METACOW: A Public-Domain, HighResolution, Fully-Digital, Noise-Free,
Metameric, Extended-Dynamic-Range, Spectral Test Target for Imaging
System Analysis and Simulation
Standard,
easily accessible, test targets have long served the field of color
imaging as a foundation for comparison of the performance of various
imaging systems and algorithms and the open and meaningful exchange
of research results. This website details the creation and application
of a new digital color test target useful for research and development
of color imaging systems. The target has several advantages over
previous types of targets that include spatial resolution, dynamic
range, spectral resolution, metameric properties, lack of noise,
and continuous tonal variations. All these features can be important
for visual assessment, computational analysis, and colorimetric
evaluation. This target, known as METACOW, is freely available to
all performing research in color imaging.
METACOW is basically a very large (4200 x 6000 pixel) full-spectral
image. It is rendered at 5nm increments, between 380 to 760...and
is thus about 3gigs in size. It is designed such that both halves
of each "cow" appear to match when illuminated with CIE D65, and
viewed with the CIE 1931 Standard Observer. This is the example
shown above. Each half of the cow is actually maximally metameric
with itself. The left half of each cow has the spectral reflectance
of the GretagMacbeth Color Checker, while the right half is a
Metameric black that has been specially calculated to maximize color
difference under Illuminant A. This type of target is designed to
test both illumination and spectral responsivities for digital imaging
solutions. Examples of illuminant (left) and observer (right) metamerism
are shown below.
The image on the
left above was rendered under Illuminant A with the CIE 2 degree
Observer, and then converted to display sRGB using the CIECAT02
chromatic adaptation transform. The image on the right was rendered
under D65 with actual digital camera spectral sensitivities. The
metameric nature of the METACOW target should be readily apparent
from these examples.
We are making the METACOW test target available to all, for use in imaging system design
and evaluation. Since it is such a large image it is not really practical to download,
so we will provide the image on DVD for a nominal $25
media & shipping/handling fee. On this fabulous DVD you get: Many Gigs of Fullsize METACOW Glory, Smaller and
Easier to Manage MINIMETACOW, Matlab Source Code for Reading and Rendering METACOW, and Much More.
Or you can download a smaller version (420x600x77) here:
Small METACOW Images
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