I. What is ISP Pipeline ISP (Image Signal Processing) pipeline refers to the processing pipeline that converts raw digital signals captured by the image processor

into final displayable high-quality images. This pipeline consists of various processing modules (i.e., algorithm modules in the ISP pipeline responsible for different functions, such as noise

reduction modules for noise suppression and sharpening modules for edge enhancement) as well as the pipeline flow (i.e., the arrangement

of these algorithm modules). Together, these components form a complete ISP Pipeline. Since mainstream image sensors today output almost exclusively Bayer-format RAW data, which cannot be viewed directly and requires

dedicated processing, the ISP Pipeline is indispensable.

II. Common ISP Pipeline

A typical ISP Pipeline contains dozens of algorithm modules, each responsible for a distinct function. These modules are connected sequentially

and operate at high speed driven by clock signals. Data flows continuously from one module to the next until all processing is completed, andthe final image is output from the pipeline.

The table below lists common ISP algorithm modules and their brief descriptions. | No. | Module Name | Function Description | |-----|-------------|----------------------| | 1 | DPC (Defective Pixel Correction) | Defective pixel correction | | 2 | BLC (Black Level Correction) | Black level correction | | 3 | BNR (Bayer Noise Reduction) | Noise reduction in RAW domain | | 4 | LSC (Lens Shading Correction) | Lens shading correction | | 5 | GB (Green Balance) | Green balance | | 6 | DG (Digital Gain) | Digital gain | | 7 | STAT | 3A statistics module | | 8 | AWB (Auto White Balance) | Auto white balance | | 9 | AE (Auto Exposure) | Auto exposure | | 10 | AF (Auto Focus) | Auto focus | | 11 | DMS (Demosaic) | Demosaicing | | 12 | CAC (Chromatic Aberration Correction) | Chromatic aberration correction, mainly for removing purple fringing | | 13 | CC (Color Correction) | Color correction | | 14 | Gamma | Gamma correction | | 15 | Dehaze | Dehazing | | 16 | CSC (Color Space Conversion) | Color space conversion | | 17 | YNR (Luminance Noise Reduction) | Luminance noise reduction | | 18 | CNR (Chroma Noise Reduction) | Chroma noise reduction | | 19 | TM (Tone Mapping) | Tone mapping | | 20 | EE (Edge Enhancement) | Edge enhancement | | 21 | DRC (Dynamic Range Compression) | Dynamic range compression | | 22 | WDR (Wide Dynamic Range) | Wide dynamic range | The modules listed above are included in the pipelines of mainstream ISP vendors. Vendors may also add other algorithm modules according

to specific requirements. The sequence and arrangement of ISP algorithm modules vary among different manufacturers. ISP flowcharts of several major vendors are

shown in the figure below.

Figure 1: HI3403 ISP Flowchart

Figure 2: CV180X & CV181X ISP Flowchart

Figure 3: RK3588 ISP Flowchart ISP workflows vary among different chip vendors, which also reflects their different priorities for ISP functions. III. Which Companies Use ISP Theoretically, all companies that require imaging rely on ISP. These include: Security surveillance Intelligent transportation Consumer electronics (mobile phones, action cameras) Drones Smart home devices (video doorbells) Medical field (medical endoscopes) Autonomous driving, etc. However, not all companies need to develop ISP from scratch. Based on the degree of ISP development, these companies can be roughly

divided into three categories: Category 1: No independent ISP development, only ISP tuning These companies generally use built-in ISP modules in SoC chips (such as Hisilicon, Novatek) and only perform ISP tuning based on

existing SoC platforms. Category 2: Develop only specific ISP algorithm modules, mainly 3A algorithms Most SoCs support users to develop custom 3A algorithms, so such companies choose to develop their own 3A algorithms while reusing

other ISP modules provided by the SoC platform.Category 3: Develop the entire ISP independently

This category typically includes: SoC vendors such as Hisilicon and Rockchip Mobile phone manufacturers such as vivo (with dedicated ISP chips) Some manufacturers that implement custom ISP algorithms based on FPGA, including medical device companies.