ISO 16505 SFR and MTF Testing for Camera Monitor Systems
ISO 16505 is the standard for camera monitor systems (CMS) that replace a vehicle’s mirrors, and its SFR chart measures the resolution of the whole camera-to-monitor chain — not just the camera. Why CMS testing images the display with a second camera, the slanted-edge SFR chart on an 18% gray background, the LW/PH spatial-frequency unit that trips people up, the multi-chart bundle ISO 16505 defines, and how it differs from ISO 12233.
ISO 15739 Noise and Dynamic Range Testing: The Grayscale Step Chart, SNR, and OECF
ISO 15739 is the international standard for measuring the noise and dynamic range of digital cameras, using a grayscale step chart of patches with known density. The mean of each patch builds the OECF and the standard deviation gives the noise, from which SNR and dynamic range follow. What the standard measures, reflective versus transmissive charts, the visual-noise metric added in the 2023 edition, why uniform illumination is the make-or-break, and how ISO 15739 complements ISO 12233 as the other half of image quality.
Symmetric vs Asymmetric Circle Grids for Camera Calibration
Circle grids are the third common OpenCV calibration pattern, in two layouts. The asymmetric (staggered) grid removes the 180° orientation ambiguity of the symmetric grid and packs more points, which is why it is the recommended layout. How findCirclesGrid counts patternSize for each (the (4,11) gotcha), why circle centroids carry a perspective bias, blob-detector tuning, and how substrate sets the accuracy ceiling.