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TDA4VM: Lens Ring Issue in Multicam App with Subsampled Resolution (TDA4VM Custom Board)

Part Number: TDA4VM

Tool/software:

 

Platform Details:

  • Processor: TDA4VM (Custom Board)

  • Linux SDK: ti-processor-sdk-linux-j7-evm-08_01_00_07

  • RTOS SDK: ti-processor-sdk-rtos-j721e-evm-08_01_00_13

 

We are using a TDA4VM-based custom board with a multicamera application (Producer-consumer). When modifying our pipeline to reduce the resolution via subsampling, we’re observing an issue where lens ring artifacts appear in camera channels 2, 3, and 4 during live quad view. Single view works fine for all the cameras.

Pipeline Details:

Initial (working) pipeline:

capture --> VISS (1936x1220) --> Shared Memory (Producer) --> 
           Shared Memory (Consumer) --> LDC (1920x1080) --> 
           Scaler (480x320) --> Mosaic

Modified (issue observed) pipeline:

capture --> VISS (1936x1220) --> Subsample (÷2 --> 960x608) -->
           Shared Memory (Producer) --> Shared Memory (Consumer) --> 
           LDC (960x608) --> Scaler (480x320) --> Mosaic

Issue Observed:

  • With the modified pipeline, lens ring artifacts appear in the output of camera channels 2, 3, and 4.

  • Camera 1 seems unaffected.

  • We suspect this may be related to using an LDC LUT generated for 1920x1080 input, while the new resolution is 960x608.


Questions:

  1. Is the observed lens ring issue due to the mismatch between the LDC LUT resolution and the input image size?

  2. Do we need to regenerate the LUT specifically for the new resolution (960x608)?

  3. Are there any guidelines or tools available for generating LDC LUTs for custom resolutions?

  4. Is there any impact or consideration specific to multi-camera channels (camera 2/3/4) that could contribute to this artifact?


We would appreciate your guidance on how to resolve this issue and ensure correct distortion correction at the subsampled resolution.

Thank you.