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Imaging Principle and Structure of Automotive Camera Modules

I. Imaging Principle
The imaging of automotive camera modules is based on the convex lens imaging principle. Light reflected from the scene is projected through the lens onto the image plane of the image sensor (Sensor). The image is then generated after photoelectric conversion, analog-to-digital conversion, and signal processing.

A complete imaging system includes:

  • Subject (environment)
  • Observer (environment)
  • Imaging device

The subject (environment) and the observer (environment) affect the imaging system's:

  • Design
  • Hardware and software implementation
  • Evaluation
  • Usage

II. Core Components
The core components of an automotive camera module (CCM) include the optical lens assembly (Lens), image sensor (Sensor), image signal processor (ISP), serializer, etc.

  • Optical lens assembly: Composed of multiple optical lens elements and integrated with an infrared cut filter (IR-Filter). It is responsible for focusing light and projecting the light from the scene within the field of view onto the sensor's image plane. The IR filter effectively blocks infrared light while transmitting visible light. Some mid-to-high-end modules are equipped with a VCM (Voice Coil Motor) and an optical image stabilization (OIS) structure, enabling precise autofocus (AF) and vibration compensation to improve imaging stability in complex scenarios.

  • Image sensor: The mainstream type is CMOS. Its photosensitive array (Pixel Array) is responsible for converting the received optical signals into analog electrical signals. An internally integrated ADC then performs analog-to-digital conversion, transforming the electrical signals into digital signals (i.e., Bayer Raw Data), which are transmitted to the ISP for subsequent processing.

(Image source: https://zhuanlan.zhihu.com/p/100777121)

  • Image signal processor (ISP): Responsible for converting the original RAW signals output by the sensor into color images through a series of algorithmic processes in the ISP pipeline.

  • Serializer: Transmits the data processed by the ISP. The corresponding deserializer (Deserializer) must be selected based on the serializer's transmission protocol (such as GMSL2 or FPD-Link III) to achieve aggregated transmission of multi-channel image data and low-latency compensation for long-distance signals.
Schematic diagram of data flow between the serializer and deserializer