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SPECTRAL COLOR IMAGING. Jussi Parkkinen Markku Hauta-Kasari IPCV 2006 August 23 th , 2006 Budapest, Hungary. Color image formation in human eye. Reproduction of color images on displays. Display characterictics. Laptop, white color on display. Color Gamut presented by.
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SPECTRAL COLOR IMAGING Jussi Parkkinen Markku Hauta-Kasari IPCV 2006 August 23th, 2006 Budapest, Hungary
Color Gamut presented by Multiprimary color display Color Gamut presented by RGB display system y Visible Color for Human Eye x Multiprimary color displays Stacked front-projection 6-primary DLP display 2x2-tiled, 2000x2000pixels rear-projection 6-primary display Conventional LCD 4-primary Flat-panel LCD
RGB-filters High and low pass filters 6 filters for Multiprimary display
Literature • Wyszecki and Stiles: Color Science. John Wiley & Sons, 2000. • The “Bible” of Color Science. Not new anymore, but basics of standard color science and basics of color are valid material. • Roy Berns: Billmeyer and Saltzman's principles of color technology. John Wiley & Sons, New York (NY), 2000. • Good and clear introduction to the color and related technologies. • Hardeberg: Acquisition and reproduction of color images : colorimetric and multispectral approaches. Dissertation.com, 2001 • Jon Yngve’s PhD thesis, good overview on spectral approach and some methods there. • Mark Fairchild: Color Appearance Models. Addison Wesley, Reading (MA), 1998. • Explains methods to be used for reproduction of colors to look correct
SPECTRAL IMAGE APPLICATIONS Jussi Parkkinen Markku Hauta-Kasari IPCV 2006 August 23th, 2006 Budapest, Hungary
Applications areas of spectral imaging • Medical imaging, telemedicine* • Cultural heritage study and digital museums* • Paper industry* • Printing industry* • Textile industry • eCommerce • Plastic industry* • Cosmetic industry • Display technology*
Example: spectral measurements Same ink in same paper (different amount of ink)
Comparison between pre-print and print color difference print pre-print
Mean reflectance spectra (Jacket) Mean whole image print pre-print Reflectance
Examination of metameric inkCourtesy by Yoichi Miyake Passport of Japan (Personal page) Color image With long pass filter >645nm
Webcam color correction Original image Color calibrated image
Observation of Spectral Reflectance Original Once Twice Three Times
Example of co-operation with local industry: Tulikivi Co. Ltd. Image optimization for a screen Crevice analysis
IMAGE OF SRGB-REPRODUCTION ON CRT DISPLAY IMAGE OF METAMERIC COLOR REPRODUCTION ON CRT DISPLAY IMAGE OF ORIGINAL SAMPLE Figure 3. Differences between original and metameric reproduction (especially lower and upper parts) are because of uneven illumination of the original sample when picture was taken. Figure 4. Original printed sample in the middle.
Spectral imaging of displays On the left ImSpector spectral camera and a 45 degree angle mirror. On the right HP laptop display and Nokia cellular phone display.
Spectral images transformed into sRGB Laptop LCD display Cellular phone display
Principal component analysis of spectral images Laptop LCD display Cellular phone LCD display 1-4 5-8 9-12 1316 17 20
Skin lesion apparently visualized by spectral color enhancement Spectral color enhancementapplied to “psoriasis vulgaris” natural color Enhancement (550nm band)
Creation of color surface coating for gray level objects • Colors of cherries, red apples and a blue pen were picked and used for coloring the cylinder.
Experimental setup no_ozone ozone Plants Lens AOTF CCD camera Halogen Lamp (pole)
Slide14 3 3 visible RED 59hours ozoneexp Before ozone exposure (0 hours) 4hours invisible NIR ozoneexp ⊿NIR had remarkable change in parts where visible damage occurred
3D Spectral Imaging System Emission Wavelength (LCTF) 400nm 410nm 600nm Spectral Imager Spectral Illuminator 350nm CCD Xenon Lamp LCTF Excitation Wavelength (Grating) Grating 360nm 570nm Total 273 images Micro-slicer Excitation-Emission Matrix Measurement of soybean Measured at National Food Reserch Institute
Proposed method Result digital camera image spectral image
Sugar Content Map(Assoc Prof S. Nakauchi Toyohashi U of Tech, Japan)
Multispectral microscopic image capturing system16-band, 2k x 2k pixels / channel
Multispectral cameras 16-band multispectral camera for still image 6-band HDTV camera for motion picture
Spectral video • Sequence of spectral images • Shown as movie on the screen • Very high memory requirements • Efficient compression needed • Shown as RGB or multiprimary
Acknowledgement Researchers in Joensuu Color Group and Dr. P. Laihanen Helsinki U of Tech, Finland Assoc Prof Y. Manabe NAIST, Japan Prof Y Miyake Chiba University, Japan Dr. Miyata National Museum of Japan History Dr. K. Miyazawa Toyohashi U of Tech, Japan Assoc Prof S. Nakauchi Toyohashi U of Tech, Japan Prof G. Nyman University of Helsinki, Finland Mr. E. Torniainen M-Real Company, Finland Assoc Prof N. Tsumura Chiba University, Japan Assoc Prof M. Yamaguchi Natural Vision Center, Japan