Question about sample script BasicLinearTransforms.py

Python: 3.8.10
OpenCV: 4.2.0


The sample python script I used: BasicLinearTransforms.py
I have tried both the OpenCV-built-in convertScaleAbs method and numpy.clip method provided in the script, however, they produce two different images.
I also tried “remove” the limit of numpy.clip by assigning them to extrem numbers, but got a third different iamge.

I have read about the source code, but stucked at convert_scale.dispatch.cpp#L99, I can’t find which function it really implement.