WO2015071786A1 - Procédé pour imagerie de réflectance spectrale à plusieurs longueurs d'onde - Google Patents

Procédé pour imagerie de réflectance spectrale à plusieurs longueurs d'onde Download PDF

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Publication number
WO2015071786A1
WO2015071786A1 PCT/IB2014/065036 IB2014065036W WO2015071786A1 WO 2015071786 A1 WO2015071786 A1 WO 2015071786A1 IB 2014065036 W IB2014065036 W IB 2014065036W WO 2015071786 A1 WO2015071786 A1 WO 2015071786A1
Authority
WO
WIPO (PCT)
Prior art keywords
spectral
illumination
spectral reflectance
wavelengths
values
Prior art date
Application number
PCT/IB2014/065036
Other languages
English (en)
Inventor
Janis Spigulis
Original Assignee
Latvijas Universitate
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Latvijas Universitate filed Critical Latvijas Universitate
Publication of WO2015071786A1 publication Critical patent/WO2015071786A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2823—Imaging spectrometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/30—Measuring the intensity of spectral lines directly on the spectrum itself
    • G01J3/36—Investigating two or more bands of a spectrum by separate detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2823—Imaging spectrometer
    • G01J2003/2826—Multispectral imaging, e.g. filter imaging

Definitions

  • the invention relates to spectral imaging, in particular to imaging of spectral reflectance distribution at a number of fixed wavelengths using a single RGB image data array.
  • X is the ratio ⁇ ( ⁇ )/ ⁇ 0 ( ⁇ ), where ⁇ ( ⁇ ) is the object surface area's reflected intensity at single fixed wavelength ⁇ and ⁇ 0 ( ⁇ ) - the reflected intensity from fully reflective reflector (the so-called white reference) under the same illumination conditions at wavelength ⁇ .
  • colour filters E.C. Ruvolo et al., Proc. SPIE, Vol. 7548, 75480A, 2010
  • Spectral filters of three colours are integrated in digital RGB image sensors, where the said filters in various combinations with external spectral filters provide increased number of spectral images (US 7612822 B2, US 2009290124 (Al), JP 2008136251 (A)).
  • Another way to obtain a set of spectral images is using of light sources that emit in a number of different spectral bands (e.g. different colour LED - WO 2008093988 (Al)) with sequential object illumination, taking a single image at each spectral band.
  • This and other technical solutions may be implemented in a single snapshot mode when RGB image is captured at poly-chromatic illumination of the object, i.e. it is illuminated simultaneously by a number of spectral bands being as narrow as possible.
  • the polychromatic illumination has particular advantages - it makes possible to reconstruct the spectral images immediately, as compared, for example, with the sequential illumination by a number of broadband LED.
  • a possibility for mapping the skin oxy-haemoglobin relative concentration distribution at bi-chromatic laser illumination by using data of a single RGB image cube has been demonstrated (J. Spigulis et al., Proc. SPIE, Vol. 7557, 75570M, 2010). The method, however, does not allow determining the specific spectral reflectance values for each image pixel at the two fixed wavelengths.
  • the limit of photo-resonse linearity is defined by the signal reflected from the white reference, which in real situations can be considerably more intense than the signal reflected from the object surface (such as a human skin). Therefore, the ratio of signal/noise (S/N) and the accuracy of the k(3 ⁇ 4) values to be determined (i - number of the spectral lines used for illumination) at particular image pixels of the object are relatively low.
  • the S/N value for the reference signals is 15 (relative error 8%), and that for the object signals is in the range between 2 and 4 ( relative error 25...50%), which results in the relative error of the k( i) values to be determined in the range between 33% and 58%;
  • the aim of the invention is to increase the imaging quality of the spectral reflectance (X) and the accuracy of the determined (X) values by using a single RGB image data set at the conditions of polychromatic illumination by several spectral lines.
  • the relative error of k(3 ⁇ 4) value to be determined is only between 18 and 23%, i.e. more than 2 times lower than using the white reference (see the example described above).
  • the application of the grey reference also allows increasing significantly the level of illumination of the object, providing linearity of photoresponse, which results in improved quality (contrast, resolution) of the acquired spectral image.
  • the replacement of white reference with the grey one significantly increases the accuracy of k( i) values to be determined, as well as the quality of the spectral reflectance images.
  • intensities of the spectral lines involved in polychromatic illumination may differ. In such cases adjustments to the image processing calculation formulas are necessary, because the signals received from all the image pixels depend not only on the spectral sensitivity S of images sensor at the selected wavelengths, but also on the relative intensities of the respective spectral lines of the illumination.

Abstract

La présente invention concerne l'imagerie spectrale, en particulier l'imagerie de la répartition de la réflectance spectrale à plusieurs longueurs d'onde fixes au moyen d'un seul jeu de données d'images RVB. Selon le procédé de la présente invention d'obtention de plusieurs images de réflectance spectrale, elles sont extraites d'un jeu de données d'images RVB numériques aux longueurs d'onde correspondant à celle utilisée par un éclairage polychromatique de la cible, fournissant une linéarité de la photo-réponse, utilisant le réflecteur de référence et prenant en compte le recouvrement des bandes de sensibilité spectrale de photodétecteur RVB, la réflectance spectrale étant calculée pour chaque pixel d'image ou groupe de pixels utilisant un réflecteur de référence de gris étalonné ayant des coefficients de réflexion à toutes les longueurs d'onde exploitées inférieures à celle de la référence blanche et par une valeur qui est proche du coefficient de réflexion le plus grand de la zone d'objet affichée. Dans le cas de différentes intensités des ligne spectrales d'éclairage, des corrections pour des valeurs de réflectance spectrale sont proposées.
PCT/IB2014/065036 2013-11-12 2014-10-03 Procédé pour imagerie de réflectance spectrale à plusieurs longueurs d'onde WO2015071786A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
LVP-13-177A LV14782B (lv) 2013-11-12 2013-11-12 Paņēmiens refleksijas spektrālā vājinājuma attēlošanai pie vairākiem viļņu garumiem
LVP-13-177 2013-11-12

Publications (1)

Publication Number Publication Date
WO2015071786A1 true WO2015071786A1 (fr) 2015-05-21

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PCT/IB2014/065036 WO2015071786A1 (fr) 2013-11-12 2014-10-03 Procédé pour imagerie de réflectance spectrale à plusieurs longueurs d'onde

Country Status (2)

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LV (1) LV14782B (fr)
WO (1) WO2015071786A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023273094A1 (fr) * 2021-06-30 2023-01-05 奥比中光科技集团股份有限公司 Procédé, appareil et dispositif pour déterminer la réflectance spectrale

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6081612A (en) * 1997-02-28 2000-06-27 Electro Optical Sciences Inc. Systems and methods for the multispectral imaging and characterization of skin tissue
RU2378976C2 (ru) * 2005-05-11 2010-01-20 Олимпус Медикал Системз Корп. Устройство обработки сигналов для устройства, предназначенного для биологических наблюдений
US20120183213A1 (en) * 2009-09-03 2012-07-19 National Ict Australia Limited Illumination spectrum recovery
US8498460B2 (en) * 2010-02-22 2013-07-30 Canfield Scientific, Incorporated Reflectance imaging and analysis for evaluating tissue pigmentation
WO2013135311A1 (fr) * 2012-03-13 2013-09-19 Latvijas Universitate Procédé et dispositif permettant de former des images de la réflectance spectrale à plusieurs bandes de longueurs d'onde

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6081612A (en) * 1997-02-28 2000-06-27 Electro Optical Sciences Inc. Systems and methods for the multispectral imaging and characterization of skin tissue
RU2378976C2 (ru) * 2005-05-11 2010-01-20 Олимпус Медикал Системз Корп. Устройство обработки сигналов для устройства, предназначенного для биологических наблюдений
US20120183213A1 (en) * 2009-09-03 2012-07-19 National Ict Australia Limited Illumination spectrum recovery
US8498460B2 (en) * 2010-02-22 2013-07-30 Canfield Scientific, Incorporated Reflectance imaging and analysis for evaluating tissue pigmentation
WO2013135311A1 (fr) * 2012-03-13 2013-09-19 Latvijas Universitate Procédé et dispositif permettant de former des images de la réflectance spectrale à plusieurs bandes de longueurs d'onde

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BEKINA AMINA ET AL.: "Multispectral assessment of skin malformations by modified video-microscope.", LATVIAN JOURNAL OF PHYSICS AND TECHNICAL SCIENCES, vol. 49, no. ISSUE, November 2012 (2012-11-01), pages 4 - 8 *
GERRIT POLDER., SPECTRAL IMAGING FOR MEASURING BIOCHEMICALS IN PLANT MATERIAL., 2004, pages 39 - 40 , 45-52, 58-60, 63-64 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023273094A1 (fr) * 2021-06-30 2023-01-05 奥比中光科技集团股份有限公司 Procédé, appareil et dispositif pour déterminer la réflectance spectrale

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LV14782A (lv) 2013-12-20
LV14782B (lv) 2014-01-20

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