Sony is introducing SNR1s [lx] as an index used to quantitatively evaluate picture quality at low illumination. SNR1s [lx] is a proprietary index advocated by Sony, and is limited to CMOS image sensors for security camera applications.
A smaller value indicates better picture quality at low illumination.
SNR1s [lx] is an acronym consisting of “SNR” (Signal-to-Noise Ratio), “1” (represents that the signal level when noise = 1 is 1), and “s” (for Security).
|SNR1s [lx] Prescribed Conditions|
|Light Source||3200 [K]|
|Target Object||18% Grey|
|Exposure time||1/60 [s]|
|Signal||G [e-] (Sensor Raw Output)|
|Noise||√Shot Noise[e-] 2 + Dark Noise[e-] 2|
|Signal : Noise||1 : 1|
Note：SNR1s is a new index proposed by Sony for picture quality at low illumination, and is limited to CMOS image sensors for security applications.
Figure 1 shows a schematic of SNR1s measurement.
Two 3200 [K] light sources illuminate an 18% gray chart from different directions, and dimming is performed to 100 [lx]. A camera is placed so that the distance from the gray chart to the imaging surface of the image sensor is 1 m, the sensitivity [e-] and dark noise [e-] are measured, and SNR1s [lx] is calculated using the relational equation (1). The luminance when equation (1) equals 1 is SNR1s [lx].
SNR1s Values of CMOS Image Sensors for Security Applications
- SNR1s [lx] : A smaller value indicates better picture quality at low illumination.
- SNR1s is a new index proposed by Sony for picture quality at low illumination, and is limited to CMOS image sensors for security applications.
- Sony reserves the right to change SNR1s values without prior notice.
- Sony cannot assume responsibility for any phenomena occurring as a result of using released SNR1s values.
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To meet this need, this technology enables both the light and dark regions to be captured clearly to achieve higher security camera visual recognition performance.