Spatial characterization of cameras for low-uncertainty radiometric measurements

10 pags.; PACS: 06.20.Dk Measurement and error theory; 07.68.+m Photography, photographic instruments; xerography; 42.72.-g Optical sources and standards; 07.60.Dq Photometers, radiometers, and colorimetersRadiometrically characterizing a camera means relating the response of every pixel of the camera to the radiance emitted by a light source. In order to accomplish this task, not only the responsivities of the pixels have to be characterized, but, in addition, their non-ideal response (dark response or non-linearity) or the radiant flux impinging on the pixel from outside its corresponding viewing solid angle. An extended uniform source developed at the PTB was used to spatially characterize a camera by determining the parameters involved in a response model. The uniformity of the source was optimized using the actual camera to be characterized, and two different procedures were used to estimate the non-uniformity of the source. These procedures are based on varying the distance from the source to the camera and, in consequence, the field-of-view area, allowing the non-uniformity of the source to be identified as the non-correlated spatial variations in the images. © 2014 BIPM & IOP Publishing Ltd.Peer Reviewe