Metrics and statistics of frequency of occurrence of metamerism in consumer cameras for natural scenes

Prasad, Dilip K.; Wenhe, Looi

doi:10.1364/josaa.32.001390

Cited by 13 publications

(5 citation statements)

References 31 publications

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“…For this, we consider the Grand Bahamas region. We plot the cosine similarity (also called the goodness of fit coefficient [ 13 , 23 , 24 ]) as follows:

…”

Section: Resultsmentioning

confidence: 99%

Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes

Prasad

Agarwal

2016

Sensors

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We propose a method for classifying radiometric oceanic color data measured by hyperspectral satellite sensors into known spectral classes, irrespective of the downwelling irradiance of the particular day, i.e., the illumination conditions. The focus is not on retrieving the inherent optical properties but to classify the pixels according to the known spectral classes of the reflectances from the ocean. The method compensates for the unknown downwelling irradiance by white balancing the radiometric data at the ocean pixels using the radiometric data of bright pixels (typically from clouds). The white-balanced data is compared with the entries in a pre-calibrated lookup table in which each entry represents the spectral properties of one class. The proposed approach is tested on two datasets of in situ measurements and 26 different daylight illumination spectra for medium resolution imaging spectrometer (MERIS), moderate-resolution imaging spectroradiometer (MODIS), sea-viewing wide field-of-view sensor (SeaWiFS), coastal zone color scanner (CZCS), ocean and land colour instrument (OLCI), and visible infrared imaging radiometer suite (VIIRS) sensors. Results are also shown for CIMEL’s SeaPRISM sun photometer sensor used on-board field trips. Accuracy of more than 92% is observed on the validation dataset and more than 86% is observed on the other dataset for all satellite sensors. The potential of applying the algorithms to non-satellite and non-multi-spectral sensors mountable on airborne systems is demonstrated by showing classification results for two consumer cameras. Classification on actual MERIS data is also shown. Additional results comparing the spectra of remote sensing reflectance with level 2 MERIS data and chlorophyll concentration estimates of the data are included.

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“…For this, we consider the Grand Bahamas region. We plot the cosine similarity (also called the goodness of fit coefficient [ 13 , 23 , 24 ]) as follows:

…”

Section: Resultsmentioning

confidence: 99%

Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes

Prasad

Agarwal

2016

Sensors

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“…En otras palabras, dos equipos fotográficos de calidad y prestaciones análogas pueden registrar un color de forma distinta. El fenómeno del metamerismo es tan presente, que existe evidencia de su presencia en un porcentaje de entre el 18% y el 20% de las fotografías tomadas en escenas naturales como frutas, escenas exteriores e interiores, como demuestra el trabajo de Dilip K. Prasad y Looi Wenhe (Prasad y Wenhe, 2015). El metamerismo de escáneres y cámaras se abordan ampliamente en la norma ISO 17321.…”

Section: Metamerismo Por Observadorunclassified

El fenómeno del metamerismo en la digitalización de las obras de arte

Fino¹,

Villagrasa²

2022

CIMED22 - II Congreso Internacional De Museos Y Estrategias Digitales

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El metamerismo es un problema que sufren especialistas en el ámbito de la fotografía y las artes gráficas. Este fenómeno provoca que dos colores que son distintos no se puedan distinguir correctamente, pudiendo ser por varias causas, entre ellas el ángulo de observación, el entorno de la pieza y la iluminación. Sobre esta última existen normativas y estándares internacionales, como la ISO3664, que trazan pautas para reducir las probabilidades de que el fenómeno se produzca, pero estas normas solo se aplican a equipos cuya finalidad es el análisis y comparación de fotografías, reproducciones y trabajos de artes gráficas, ya sean impresas o vistas en pantallas. Los citados estándares están algo desactualizados respecto a los adelantos en el campo que ha hecho la iluminación LED, así que fueron redactados en una época de iluminantes menos fiables, con periodos cortos de vida y deterioros cromáticos rápidos. La actual sindemia ha acelerado los procesos de digitalización de muchos museos. Estas instituciones están dirigiendo cuantiosos recursos a la disposición de sus fondos y colecciones en portales Web diseñados a tal fin, y observan con interés los adelantos de la era digital, como las realidades virtuales y los metaversos, a los que seguramente tardarán poco en subirse de forma masiva. En este contexto, uno de los primeros pasos que se tiene que dar es la toma de imágenes de las colecciones que se quieren poner a disposición del público digital, y es aquí donde el fenómeno del metamerismo puede entorpecer la correcta digitalización de las obras, porque si la obra presenta colores metaméricos, la fidelidad de la toma de datos puede quedar comprometida si no se cuenta con iluminantes de referencia adecuados, que por lo general son inexistentes en los departamentos de fotografía de los museos. Dentro del amplio abanico de iluminantes, nos centramos en el estudio de una reciente tecnología que permite generar un espectro continuo, más cercano a la luz solar, y que no solo nos permite aproximarnos satisfactoriamente a los iluminantes de referencia establecidos por la CIE (Commission internationale de l'Éclairage) sino que carece de los problemas que adolecen iluminantes de referencia de tecnologías obsoletas, como sus espectros discontinuos, bajos índices de reproducción cromática, bajas eficiencias y la gran dificultad técnica que presentan algunos de ellos para adaptarse adecuadamente a las exigencias de trabajo de los departamentos de fotografía de los museos.

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“…At the same time, metamerism is an affecting element in color-based study. The origin colors of an object could be different under the influence of luminance, sensors, lighting devices, and so on, according to Prasad and Wenhe [36]. It reminds that the lighting system and display devices should keep consistent according to the same indexes of color temperature and color space in the experiment.…”

Section: Color Heoriesmentioning

confidence: 99%

Research on the Colors of Military Symbols in Digital Situation Maps Based on Event-Related Potential Technology

Niu

Xue

et al. 2020

IJGI

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Under the trend of increasingly informationalized military operations and the increasing maneuverability of combat units, military commanders have put forward higher requirements for the accuracy and promptness of information on battlefield situation maps. Based on the sea battlefield, this paper studies the pros and cons of the color matching of military symbols on sea situation maps. Fifteen colors, where each Hue had five colors, were chosen using the Munsell Color System according to Chroma axis and the Value axis on a span of 2 and 4. By collecting and analyzing the P300 EEG data, reaction time data, and accuracy data of 20 subjects, a better color matching selection of military symbols on pure color (L = 85, a = −10, and b = −23) sea situation maps is put forward, and the conclusions are as follows: (1) the different colors all cause the P300 component in EEG experiment. Among them, the P300 amplitude that is caused by military symbols with lower Chroma is smaller and the latency is shorter, indicating that the user experience and efficiency of low Chroma color symbols will be better than those with high Chroma color symbols. (2) High Value color map military symbols cause higher P300 amplitude and longer latency. According to the results above, this paper puts forward three optimized colors, namely, blue (L = 39, a = 20, and b = −49), green (L = 80, a = −72, and b = 72), and red (L = 20, a = 41, and b = 28). Additionally, three map interfaces were designed to confirm the validity of these colors. By means of applying the NASA-TLX (Task Load Index) scale to evaluate the task load of the confirmation interfaces, it can be concluded that these three optimized colors are preferred by users who are skilled in GIS and interface design. Therefore, the research conclusion of this paper can provide important reference values for military map design, which is helpful in shortening the identification and judgment time during the use of situation maps and it can improve users’ operation performance.

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Metrics and statistics of frequency of occurrence of metamerism in consumer cameras for natural scenes

Cited by 13 publications

References 31 publications

Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes

Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes

El fenómeno del metamerismo en la digitalización de las obras de arte

Research on the Colors of Military Symbols in Digital Situation Maps Based on Event-Related Potential Technology

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