1、RCCB sensor
I accidentally saw a sensor with special specifications, RCCB (Red-Clear-Clear-Blue) sensor. When I heard this term for the first time, I looked it up if I didn’t know. It was found that RCCB sensor is a sensor widely used in automobiles. industry because their sensitivity and signal-to-noise ratio (SNR) are superior to traditional Bayer (RGGB) sensors.
There are some differences from the common RGGB bayer mode. The common color filter array RGGB: one red light, one blue light, and two green light filters. Each pixel can only sense one color of light. The RCCB sensor replaces the G pixels of the traditional bayer format with fully transparent pixels to increase the amount of light entering and improve the signal-to-noise ratio of the sensor. The RYYB sensor supplied by Sony to Huawei is also designed to increase the amount of light entering.
Of course, color-related aspects such as demosaic interpolation and color correction of RCCB and RGGB need to be adjusted separately.
The picture below shows a fully transparent snesor and a sensor with a filter. The filter can selectively let light of a certain wavelength band pass through:
The schematic diagram of RCCB and rggb sensor is as follows:
RCCB will reduce color discrimination while improving sensitivity. A more special kind is RCCC: 75% is transparent transmission, and the remaining 25% is a filter that detects red light. The advantage of RCCC is that it has high light sensitivity and is suitable for low-light environments. Since RCCC only has a red light filter, it is mainly used in occasions that are sensitive to red signs (such as traffic light detection). RCCB: 50% of the part is transparent transmission, and the remaining red light and blue light filters each account for 25%. The low-light sensitivity of RCCB is slightly worse than that of RCCC (less Clear part), but its ability to distinguish colors is better, and the collected images can be used for both machine analysis and human eye observation.
2. Improve indicators
RCCB improves sensitivity and dynamic range, and it improves image brightness. These two indicators will be improved.
Sensitivity: Sensitivity is one of the important parameters of the chip, and it has two physical meanings. One is the photoelectric conversion capability of an optical device, which has the same meaning as the responsivity. That is, the sensitivity of the chip refers to the output signal voltage (current) per unit exposure within a certain spectral range. The unit can be nanoampere/lux nA/Lux, volt/watt (V/W), volt/lux (V/Lux) ), volts/lumens (V/lm). The other refers to the ground radiation power (or illumination) that the device can sense, which has the same meaning as the detection rate. The unit can be expressed in watts (w) or lux (Lux).
Dynamic range: A measure of an image sensor's ability to capture both light and dark objects in the same photo, usually defined as the logarithm of the ratio of the brightest signal to the darkest signal.
3. RCCB sensor effect
RCCB increases the amount of light entering and can improve image brightness in dark places, as shown below:
Summarize
The RCCB sensor improves the image quality by increasing the amount of low beam. It is difficult to correct the color and requires some trial and error.
reference
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