winter 2011

Rochester Institute of Technology

Chester F. Carlson Center

for Imaging Science

Munsell Color Science Laboratory

54 Lomb Memorial Drive

Rochester, New York

14623-5604

(585) 475-7189

Displaying HDR PrintsHigh dynamic range (HDR) displays are enabling new advances in visual psychophysics, but commercial HDR displays are both expensive, and difficult to calibrate colorimetrically. Homebrew HDR displays incorporating LCD panels and digital projectors are relatively inexpensive and can be calibrated, but building such displays requires sophisticated technical skills. We have developed a low-cost, color-calibrated HDR display for vision research that can be constructed and used by researchers without the need for specialized equipment or advanced engineering abilities. Inspired by the work of Bimber et al., this reflective HDR display incorporates an inkjet printer, a digital video projector and a digital camera. To display an HDR image, the image is first processed t h r o u g h t h e i C A M 0 6 i m a g e appearance model to produce a standard dynamic range (SDR) image that is sent to the printer. The digital video projector is then roughly positioned so its image field covers the p r i n t . C u s t o m c a m e r a - b a s e d structured-light image registration software then automatically aligns the projected and printed images. A color calibration module then measures the print colors and determines the values to send to the projector to achieve the best possible reproduction of the original HDR image. This iCAM-based approach to HDR color reproduction goes substantially beyond prior work in terms of its colorimetric accuracy. With respect to intensity and dynamic range, because the print area is substantially smaller than a projector’s typical field size, the maximum intensity in the combined image can be quite high, and the current display has a peak luminance around 2000 cd/m2 with a dynamic range greater than 20,000:1. While the print-based nature of this display does limit its usefulness for interactive studies, its low-cost, do-it-yourself design, and its ability to be calibrated should make it a valuable addition to the vision researcher’s laboratory.

-Dan Zhang

Save the Date ... The 2011 MCSL industrial summer short course will be held June 14-16, 2011.

Check our website for details.

Summer Life of an Undergraduate Researcher This summer, I was an undergraduate student

researcher in the Munsell Color Science Lab. As an undergrad researcher, I was assigned to a joint project between Mark Fairchild of MCSL and Christye Sisson of the Biomedical Photography Department. The problem presented was that each of Christye’s fundus cameras (special cameras used to image the human retina through the iris) treated color in vastly different ways. This provides diagnostic trouble when a single patient is imaged on multiple cameras as the varying colors could possibly lead to a different diagnosis of the same problem. The goal of this project was to apply color management techniques to these fundus cameras. Along with the project came two high school interns to help out with the research and along with the interns came desks decorated with bright colors, hearts and lots of pictures of puppies.We started out the research by acquiring a fake eye, which the girls lovingly named Mr. Jones, that roughly modeled the curvature and refractive power of a normal eye. Color patches were then inserted in the back of the model eye and images were captured with each of the digital fundus cameras. There was a steep learning curve with those cameras as they are unlike any camera we had ever seen before, but we made it through.The next step was to process the hundreds of images we acquired, cropping and averaging sRGB values in order to obtain a single sRGB triplet for each color patch from each camera. These sRGB values were then compared to the sRGB values from the original color patches and a 3x3 matrix was developed for each camera to take them back to a baseline color that was the same across the board.For me, this summer was an investigative experience into the world of color science in order to find if it was something I could do as a career. For my interns, this summer was not only an experience in color science, but also an insight into college. I can safely say that all of us were pleased with what we found. Besides learning all the characters from The Secret Life of an American Teenager (a TV show) and Justin Bieber lyrics (both of which I learned from working with two teenage girls all summer), I also got to learn the basics of color management and some of what it takes to be a color scientist. I am excited to pursue some form of degree in color science once I complete my undergraduate education. While I can’t say the interns also fell in love with color science (I believe they have dreams of being doctors. Evidently eyeballs weren’t enough for them), they definitely enjoyed their time at MCSL and will take their experiences on with them.   

-Joel Witwer

Yiheng CaiI am a visiting scholar from B e i j i n g U n i v e r s i t y o f Technology. My research is mainly focused on image processing. One project I am working on is about tongue image acquisition and analysis for Traditional

Chinese Medicine. We need to develop an instrument that can provide accurate tongue rendering to perform Traditional Chinese Medicine automatically by analyzing color, texture and other characterization of tongue images. The research achievements can help physicians make objective and quantitative diagnoses and reduce the dependence on their experience and knowledge.During the development of the instrument, we were faced with a problem. That is the color of the image will change when the camera or the illumination is changed. This will have influence on not only the image display but also the analysis results. This is why I came to MCSL. I really want to study and work here to find a good solution for tongue image color reproduction.

Jie FengI am a teacher at the S c h o o l o f P h y s i c s & E lec t r i cs I n fo rmat ion , Yunnan Normal University, China. I received my Ph.D. from Beijing Institute of Technology in 2008. I have been awarded financial s u p p o r t f r o m C h i n a Scholarship Council to

pursue further research in the USA as a post-doctoral fellow.My current research interest is the application of multispectral imaging technology. I plan to do some further research on 3D-Spectral Capture which is a part of MCSL’s current research. In October 2010, I came to MCSL. I plan to study and research under Prof Roy Berns’ direction as a post doctor at the laboratory. Additionally, I will take the opportunity to attend some classroom and research courses. I strongly believe that I can make significant progress in my research on multispectral imaging, 3D-Spectral Capture and research methodology at MCSL.

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Congratulations ... Marissa Haddock was awarded the 2010 Kodak Fellowship in Film Preservation by the Association of Moving Image Archivists (AMIA). This award involves a stipend, AMIA conference attendance, as well as a summer internship at a film restoration facility. She is currently attending the L. Jeffery Selznick School of Film Preservation at George Eastman House and plans to pursue projects in moving image preservation, with an emphasis on color film material.