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Read a digital-camera noise test without confusing it with film grain
Noise measurements describe electronic image variation under controlled capture conditions.
A high-ISO test chart can show camera noise, but it does not directly predict how a processed phone portrait will look. Separate the measurement from the camera’s final rendering.
Know the measured sources
ISO 15739 discusses noise measurement for digital still images and identifies sources including photon shot noise, readout noise, dark current and quantisation. Image processing can change the visible pattern, so raw measurements and finished JPEG appearance are different.
Evidence: International standard
Compare at matched output size
Resize test captures to the same strip dimensions before judging visible noise. A full-resolution crop can exaggerate noise that disappears at print size, while heavy denoising can erase hair and skin texture.
Report capture conditions
Record exposure, sensitivity, file format, lighting and processing. Avoid saying a camera is noisy without the conditions. For an event setup, test the actual low-light scene and a normal portrait, then decide whether more light or a different exposure is the most practical change. The standard addresses electronic still-picture imaging, so it does not define how film grain should be measured.
Evidence: International standard
Sources & further reading
Sources for the specific facts and product descriptions above. Our worked examples, interpretations and practical suggestions are original editorial guidance.
- ISO, ISO 15739:2023 Noise MeasurementsInternational standard