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 | |
|---|---|
| Application | Security Camera |
| Light Source | 3200 [K] |
| Target Object | 18% Grey |
| F number | 1.4 |
| Exposure time | 1/60 [s] |
| Linear Matrix | without |
| 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.
NIR
Darkness arouses unease. To capture images even in dark areas and ensure peace of mind, efficient capture of near-infrared light is essential. Sony’s photodetectors are made with the optimum structure to capture near-infrared light and provide clear images even in darkness.
HDR
With many security camera images in which light and dark regions coexist, there is a need to clearly capture both regions.
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.
Source: https://www.sony-semicon.co.jp/e/products/IS/security/technology.html
