INDIRECT ABSOLUTE RADIOMETRIC CALIBRATION METHOD Russian patent published in 2020 - IPC G01J1/10 G12B13/00 

FIELD: physics.

SUBSTANCE: invention relates to a method of absolute radiometric calibration of filming equipment. Disclosed method is based on two-stage illumination of a charge-coupled device (CCD) matrix: at the first stage, a reference signal illuminates a portion of photosensitive elements (PSE), and on the second one, all PSE are illuminated with the signal of a diffusely scattering object with unknown luminance E_k. For PSE, the illuminated reference signal is determined as the transmission coefficients of the output signal of the difference between the ratio of exposure of the photosensitive member E_k optical reference signal and output a signal corresponding to dark current, to the value of the reference optical signal and the normalizing coefficient as the ratio of the output signal at illumination with the signal with unknown luminance E_k the output signal when the standard signal is illuminated. All PSEs, which are not illuminated by the reference signal, are divided into groups based on the number of PSEs illuminated by the reference signal. Inside each group, the ratio of the output signals of the PSE, which are not illuminated by the reference signal, is determined to the output signal of the PSE bound to the given group, with its illumination by an unknown signal. Then, for each element from the group, the calibration factor is determined as the product of the normalizing coefficient and transmission coefficient of the photosensitive element attached to the group, illuminated by the reference optical signal, to which difference of values of output signals of all elements of the captured image and signals corresponding to dark currents is multiplied.

EFFECT: technical result is providing absolute radiometric calibration of all elements of CCD matrix when illuminated with reference optical signal of only part of PSE.

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