Abstract
This paper presents that the opto-electrical characteristic of a typical CCD based digital camera is nonlinear. It means that digital electric signal of the camera's CCD detector - is not a linear function of the luminance value on camera's lens. The opto-electrical characteristic feature of a digital camera needs to be transformed into a linear function if this camera is to be used as a luminance distribution measurement device known as Imaging Luminance Measurement Device (ILMD). The article presents the methodology for obtaining the opto-electrical characteristic feature of a typical CCD digital camera and focuses on the non- linearity correction method. Full Text: PDF ReferencesD. Wüller and H. Gabele, "The usage of digital cameras as luminance meters," in Digital Photography III, 2007, p. 65020U CrossRef P. Fiorentin and A. 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Highlights
H owever, the user of Imaging Luminance Measurement Device (ILMD) gets the luminance image [19] wh ich gives information about spatial distribution of luminan ce. It is because ILMD measures object luminanceat many points at thesametime
It consists of a lens system, V( ) correction f ilt er, C C D sensor with an amplifier, low noise analog electronics, A/D conversion and digital data transfer. This kind of device needs to be calibrated. It mean s t hat the relationship between the values of quantities indicated by a CCD sensor and the corresponding valu es rea lized by luminance standard needs to be set
I n the case of ILMDs, the luminance unit is candela per squa re meter
Summary
It is based on the luminance standard OL 455. Th e results of calibration allow to assign the values of standard luminance to the values measured by ILM D. I n the case of ILMDs, the luminance unit is candela per squa re meter. 3 ‒ photometric head, 4 ‒ shutters, 5 ‒ digital camera. 2. Technical parameters of OL 455 standard
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