Image Signal Processor Fault Isolation via Embedded Test Signals
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Solution Overview
Problem
Image signal processors (ISPs) in image processing systems can generate inaccurate images due to faults, leading to issues in advanced driver assistance systems (ADAS) functions.
Innovation Solution
A method and device for generating input signals to ISPs based on raw image signals and input test signals, and determining ISP faults by comparing output test signals with target values, using a fault detection circuit to identify and isolate faulty ISPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an ISP processes a raw image signal to generate an image for ADAS functions, then the image processing capability is improved, but the risk of fault-induced inaccurate image generation increases
Solution Approach 1:
The patent applies preliminary action by generating a test signal before the ISP processes the raw image signal, and inserting this test signal into the input signal. The fault detection circuit then checks the test signal output from the ISP to determine if a fault exists before it affects the actual image processing, thus preventing inaccurate image generation while maintaining processing capability
Solution Approach 2:
The patent uses a test signal as an intermediary element to detect faults in the ISP. The test signal is inserted into the input signal, processed by the ISP along with the raw image signal, and then extracted and checked by the fault detection circuit. This intermediary test signal allows fault detection without affecting the normal image processing function
2Reliability
If a fault detection circuit is added to determine ISP faults, then the reliability of image processing is improved, but the device complexity increases
Solution Approach 1:
The patent extracts the test signal from the processed output signal to create a separate test signal output. The fault detection circuit then only needs to check this extracted test signal rather than analyzing the entire processed signal, simplifying the fault detection process while maintaining reliability
Solution Approach 2:
The patent creates a copy of the test signal through the ISP processing chain and uses this copy for fault detection. The test signal is inserted into the input, processed by the ISP to create a test signal output, and then this output copy is checked by the fault detection circuit to determine ISP health without affecting the main image processing function
3Measurement precision
If a test signal is inserted into the input signal for fault detection, then the fault detection accuracy is improved, but the processing time increases
Solution Approach 1:
The patent merges the test signal with the raw image signal to form a combined input signal that is processed by the ISP in a single operation. The test signal is inserted into the input signal, and both the test signal and raw image signal are processed together by the ISP, extracting the test signal output from the processed signal. This merging approach allows fault detection to occur during normal image processing without requiring separate processing time
Solution Approach 2:
The patent makes the ISP perform multiple functions simultaneously: processing the raw image signal for ADAS output and processing the inserted test signal for fault detection. The ISP processes both signals through its processing chain, and the fault detection circuit checks the test signal output, allowing the same hardware to serve both image processing and fault detection purposes without additional processing time
Data Source
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AI summary
Disclosed is a method of determining an image signal processor (ISP) fault, performed by an image processing device. The method includes receiving a first raw image signal that is at least a portion of an image signal captured by an image sensor of a first camera, based on the first raw image signal and a first input test signal, generating a first input signal, generating, by a first ISP, a first output signal by processing the first input signal, obtaining a first output test signal corresponding to the first input test signal from the first output signal, and based on the first output test signal, determining whether a fault occurs in the first ISP.