background noise with Lepton 2.5 and Pure Thermal Mini board

[巫佳真]

I would like to ask a question about lepton 2.5. There is always noise in the background of the image I detected. The picture below is the display result of the app provided by the Pure Thermal Mini board manufacturer, and the canny image processed by opencv, but the background is noisy. The noise cannot be eliminated. I turned off all the lights and the noise still exists. Is this an issue with the quality of the Lepton 2.5 product?