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

Multiprimary color displays Conventional LCD4-primary Flat-panel LCD 2x2-tiled, 2000x2000pixels rear-projection 6-primary display Stacked front-projection 6-primary DLP display y x Visible Color for Human Eye Color Gamut presented by Multiprimary color display Color Gamut presented by RGB display system

RGB-filters High and low pass filters Multiprimary display 6 filters for

Literature Wyszecki and Stiles: Color Science. John Wiley & Sons, –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), –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), –Explains methods to be used for reproduction of colors to look correct

SPECTRAL IMAGE APPLICATIONS Jussi Parkkinen Markku Hauta-Kasari IPCV 2006 August 23 th, 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 *

Testimage for printing quality test (newspaper)

Some sample spectra for original and print

Example: printing inks and measurement

Example: spectral measurements Same ink in same paper (different amount of ink)

Comparison between pre-print and print pre-print print color difference

Mean reflectance spectra (Jacket) Mean whole image Reflectance print pre-print

Examination of metameric ink Courtesy by Yoichi Miyake Color image With long pass filter >645nm Passport of Japan (Personal page)

Example of fluorescent colors

Examples: color characterization

Videoconferencing using web-cam

Webcam color correction Original imageColor calibrated image

Simulation of illuminant change

Spectral component images (400, 550, 700 nm)

Church

Observation of Spectral Reflectance Original Once Twice Three Times

Example of co-operation with local industry: Tulikivi Co. Ltd. Crevice analysisImage optimization for a screen

IMAGE OF ORIGINAL SAMPLE IMAGE OF SRGB-REPRODUCTION ON CRT DISPLAY IMAGE OF METAMERIC COLOR REPRODUCTION ON CRT DISPLAY Figure 3. 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. 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 displayCellular phone display

Principal component analysis of spectral images 1- 4 Laptop LCD displayCellular phone LCD display

Acquiring of spectral face images

Part of the database

Spectral color enhancement applied to “ psoriasis vulgaris ” natural color Enhancement (550nm band) Skin lesion apparently visualized by spectral color enhancement

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.

CCD camera ＡＯＴＦ Lens Halogen Lamp (pole) Plants Experimental setup no_ozone ozone

Before ozone exposure （ 0 hours) Slide1 4 ozone exp visible RED 59 hours ozone exp 4 hours ⊿ NIR had remarkable change in parts where visible damage occurred ３ ３ invisible NIR

Measurement of soybean Emission Wavelength (LCTF) 400nm410nm600nm 350nm Excitation Wavelength (Grating) 360nm 570nm Total 273 images Excitation-Emission Matrix Spectral Illuminator Spectral Imager Xenon Lamp Grating Micro-slicer 3D Spectral Imaging System CCD LCTF Measured at National Food Reserch Institute

Result Proposed method spectral image digital camera image

Sugar Content Map (Assoc Prof S. Nakauchi Toyohashi U of Tech, Japan)

Multispectral microscopic image capturing system 16-band, 2k x 2k pixels / channel

16-band multispectral camera for still image Multispectral cameras 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. LaihanenHelsinki U of Tech, Finland Assoc Prof Y. ManabeNAIST, Japan Prof Y MiyakeChiba University, Japan Dr. MiyataNational Museum of Japan History Dr. K. MiyazawaToyohashi U of Tech, Japan Assoc Prof S. Nakauchi Toyohashi U of Tech, Japan Prof G. NymanUniversity of Helsinki, Finland Mr. E. TorniainenM-Real Company, Finland Assoc Prof N. TsumuraChiba University, Japan Assoc Prof M. YamaguchiNatural Vision Center, Japan