Steve on Image Processing

December 13th, 2007

How can I possibly resist the opportunity to post about something called METACOW?

The Munsell Color Science Laboratory at the Rochester Institute of Technology (RIT) has made available METACOW: "A Public-Domain, HighResolution, Fully-Digital, Noise-Free, Metameric, Extended-Dynamic-Range, Spectral Test Target for Imaging System Analysis and Simulation."

"[...] 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."

"[...] 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."

According to the web site, the DVD includes MATLAB code for reading and rendering METACOW.

07:30 UTC | Posted in Uncategorized | Permalink |

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5 Responses to “METACOW”

1. Jeff Mather replied on December 13th, 2007 at 09:19 UTC :
   

   That is awesome! Of course, you left out the best phrase from the page: “Each half of the cow is actually maximally metameric with itself.”

   I know what I hope I get in my stocking this year….

2. Jason Brown replied on December 13th, 2007 at 15:49 UTC :
   

   It’s kind of funny…I go to RIT but haven’t heard anything about it in any of or News e-mails or on the University News website…had to find it here.

3. Tim Davis replied on December 16th, 2007 at 07:06 UTC :
   

   I think you could use some definitions here:

   Computer navigation system declares “return to normality”. Arthur: “You can talk about normal ’til the cows come home”. Ford: “What’s normal?”. Trillian: “Where’s home?”. Zaphod: “What are cows?” (Hitchhiker’s Guide to the Galaxy).

   Thus:

   COW matrix: C(i,j) is the ij-th Coefficient Of Wavelet basis.

   “return to normality”: an orthogonalization process that ensures all columns of C(i,j) are orthonormal.

   “Normal”: two cows at right angles to each other. Exercise left to the reader (see also http://en.wikipedia.org/wiki/Cow_tipping , not to be confused with tipping the waiter-COW at the Restaurant at the End of the Universe).

   “Home”: see “doc clc” and “doc home” … returns the CURSOR (COW User Reference for Status Output Recall) to the upperleft most corner of the Command Pasture.

   Dihydrogen Monoxide: a dangerous chemical regulated by the FDA. Introduction of this chemical is prohibited by the FDA into the COW output matrix (also known as the Modifield Incomplete LK factorization, or MILK). However, there is no constraint on the introduction of this chemical into the COW matrix prior to generation of the MILK output. See www.dhmo.org for more details.

4. Tim Davis replied on December 16th, 2007 at 12:59 UTC :
   

   The MILK factorization decomposes a COW into its Lower and Udder triangular factors. After this decomposition, the COW is quite tender and solves easily (also refered to as a Chew-less-ky factorization).

   In the images at the METACOW site, those small protuberances underneath the COW (source of the MILK factors) are up-turned L-shaped membranes (they are MATLAB-compatible COW’s after all).

5. Tim Davis replied on December 16th, 2007 at 13:02 UTC :
   

   Then of course there’s the Balanced/Equilibrated Eigenvalue Factorization (a Chewlessky BEEF).

   OK, OK, I’ll stop ;-)

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