{"id":922,"date":"2026-06-08T02:29:14","date_gmt":"2026-06-08T06:29:14","guid":{"rendered":""},"modified":"2026-08-17T18:20:15","modified_gmt":"2026-08-17T18:20:15","slug":"em-radiance","status":"publish","type":"post","link":"https:\/\/aboutyou.name\/?p=922","title":{"rendered":"EM Radiance"},"content":{"rendered":"

Radiance is used to characterize diffuse emission and\/or reflection of EM<\/span><\/a> radiation, or to quantify emission of neutrinos<\/span><\/a> and other particles. Historically, radiance is called “intensity” and spectral radiance is called “specific intensity”. <\/span><\/span><\/p>\n

Radiance is useful because it indicates how much of the power emitted, reflected, transmitted or received by a surface will be received by an optical<\/span><\/a> system looking at that surface from a certain view angle. <\/span><\/span><\/p>\n

Spectral radiance expresses radiance as a function of frequency or wavelength. Radiance is the integral of the spectral radiance of all frequencies\/wavelengths. <\/span><\/span><\/p>\n

For radiation emitted by an ideal black body at a given temperature, spectral radiance is governed by Planck’s law, while the integral of radiance over the hemisphere into which it radiates, is governed by the Stefan\u2013Boltzmann law. <\/span><\/span><\/p>\n

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Hyperspectral imaging collects and processes data from across the EM spectrum. Its goal is to obtain the spectrum for each pixel in the image of a scene, with the purpose of finding objects, identifying materials, or detecting processes.<\/span><\/span><\/p>\n

The human eye sees visible light in three bands (red, green & blue). Spectral imaging divides the spectrum into many more bands. This technique of dividing images into bands can be extended beyond the visible. <\/span><\/span><\/p>\n

In hyperspectral imaging, the recorded spectra have a fine wavelength resolution and cover a wide range of wavelengths.<\/span><\/span><\/p>\n