A multispectral imaging system enabling biological tissue identifying and differentiation is presented. The measurement
of β(λ) spectral radiance factor cube for four tissue types (beef muscle, pork muscle, turkey muscle and beef liver)
present in the same scene was carried out. Three methods for tissue identification are proposed and their relevance
evaluated. The first method correlates the scene spectral radiance factor with tissue database characteristics. This method
gives detection rates ranging from 63.5 % to 85 %. The second method correlates the scene spectral radiance factor
derivatives with a database of tissue β(λ) derivatives. This method is more efficient than the first one because it gives
detection rates ranging from 79 % to 89 % with over-detection rates smaller than 0.2 %. The third method uses the
biological tissue spectral signature. It enhances contrast in order to afford tissue differentiation and identification.
In order to build biological tissues spectral characteristics database to be used in a multispectral imaging system a tissues
optical characterization bench is developed and validated. Several biological tissue types have been characterized in vitro
and ex vivo with our device such as beef, turkey and pork muscle and beef liver. Multispectral images obtained have
been analyzed in order to study the dispersion of biological tissues spectral luminance factor. Tissue internal structure
inhomogeneity was identified as a phenomenon contributing to the dispersion of spectral luminance factor. This
dispersion of spectral luminance factor could be a characteristic of the tissue. A method based on envelope technique has
been developed to identify and differentiate biological tissues in the same scene. This method applied to pork tissues
containing muscle and fat gives detection rates of 59% for pork muscle and 14% for pork fat.
KEYWORDS: Color difference, Printing, Color management, Image quality, Visual system, CMYK color model, Color reproduction, Software development, Algorithm development, Colorimetry
Increased interest in color management has resulted in more options for the user to choose between for their color
management needs. We propose an evaluation process that uses metrics to assess the quality of ICC profiles,
specifically for the perceptual rendering intent. The primary objective of the perceptual rendering intent, unlike
the media-relative intent, is a preferred reproduction rather than an exact match. Profile vendors commonly
quote a CIE ΔE*ab color difference to define the quality of a profile. With the perceptual rendering intent, this
may or may not correlate to the preferred reproduction.
For this work we compiled a comprehensive list of quality aspects, used to evaluate the perceptual rendering
intent of an ICC printer profile. The aspects are used as tools to individually judge the different qualities that
define the overall strength of profiles. The proposed workflow uses metrics to assess each aspect and delivers a
relative comparison between different printer profile options. The aim of the research is to improve the current
methods used to evaluate a printer profile, while reducing the amount of time required.
The scope of TC 1-36 is to supplement the CIE colorimetric observers with color matching data that make a clear connection between the color specification and the underlying physiology. After careful examination of color matching data, TC 1- 36 has agreed on proposing a continuous fundamental observer with data from 10° to 1°. The 10° color matching measurements of Stiles and Burch (1959) will provide the basic data for this continuous fundamental observer. Fundamental response curves will be derived as a function of field size, taking into account the macular pigment, the ocular media and the photopigment optical densities.
This study aims at establishing the relationship between the spectral transmission characteristics of tinted ophthalmic lenses and the visual percept of the observer looking through. We hypothesize that the rating of tinted lenses originates from what the observer sees rather than what the glass looks like. We develop a model for color acceptance by calculating the color distortions for a collection of colored surfaces that are representative of the real environment using the spectral reflectance of the surfaces and the spectral transmittance of the lens. Then we apply the model to a collection of real tinted ophthalmic lenses and derive statistical indices that describes the global color distortion induced by each lens. Preliminary results show a significant agreement between the subjective rating and the objective color distortion index. We conclude that our model allows to predict the acceptance/rejection judgement of observers for a tinted ophthalmic lens of known spectral transmittance.
Gloss is a visual attribute, which, as well as color, provides qualitative information on the surrounding objets. The relevant physical quantity for gloss measurement is the BRDF that characterizes the geometrical distribution of the reflected light on the sample. We hypothesize that the light reflection on a glossy sample is split in 2 parts. The volume diffusion and the surface reflection. We assume that the surface of the sample consists of tiny mirror facets the orientation of which is specific of the surface microstructure. Each facet is the source of specular reflection. With this hypothesis, we have calculated a theoretical model of the BRDF according to Fresnel laws. We have applied the model to black and white painted samples of various gloss indexes. In addition, we have acquired real measurements of the BRDF of the same samples by using a new device which gives the compete measurement of the luminance geometrical distribution in the hemisphere. The comparison of the measurements and the theoretical model shows that, for this series of samples, the facet hypothesis is reliable and makes it possible to model the real BRDF in all directions.
We have proposed colormaps to replace a widely used 216 colors palette in order to allow a designer with normal color vision to simulate the colors seen by dichromats. As dichromats lack one class of cone photo pigment, they confuse colors that differ only in the excitation of the missing class of photo pigment. The method is based on the LMS colorimetric system, which specifies colors in terms of the relative excitations of the cones. We have constructed a rule to reduce any set of confused colors to a single three- component specification. We have introduced a modification, assuming that the video display primaries and nominal white are representative of recent standards for Cathode Ray Tube monitors and that its video-transfer function is a power function with an exponent of 2.2. For everyday practice, replacing a normal palette by a reduced palette provides an immediate warning of possible losses of readability of a display by color-deficients.
KEYWORDS: Sensors, Temperature metrology, Electronic filtering, Color difference, Standards development, Colorimetry, Signal processing, Information operations, Gadolinium, Reflectivity
Measurements of the spectral sensitivities of the Buried Triple p-n Junction color detector have been carried out in the -60 degrees C to 60 degrees C temperature range. Temperature behavior of the photo-currents are described. Variations in the BTJ CMFs have been calculated and a procedure for colorimetric characterization which consider the detector temperature is proposed. Using the proposed procedure, color differences between the detector specifications and the color coordinates in the CIE standard have been determined. The validity of this procedure is evaluated in terms of color shift between the detector specifications caused by a temperature change.
The operation and the colorimetric characterization of a buried triple p-n junction (BTJ) tristimulus detector are presented. A method defining a linear transformation between the detector color space and the C.I.E. standard is proposed. With the least squares fitting to the third order a mean color difference of 2.15 CIELAB units, between the detector response and the C.I.E. specification is predicted. The temperature effects on the detector and the linear transformation accuracy are studied between minus 60 degrees Celsius and 60 degrees Celsius. The color shifts in the detector specifications due to a temperature variations are smaller than 0.5.
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