Hi again and thanks for that description of the layout and image.
What I SUSPECT you are seeing is quite a bit of "washout" when in Night-mode, with that washout being caused by ALL of the LEDS on the camera illuminating the white background of the thermometer.
I found a video of a similar system that shows a camera in night-mode, that may be similar to what you are seeing. Here is a link to that video, and it should appear at about the 12 minute mark. Please take a look and notice the lower-left camera showing on the screen.
As mentioned above, I believe this washout is caused by the multiple LEDs lighting the area, and with these cameras rated at over 100 feet of "night vision" capability, and the thermometer being only six feet away - that is probably just "too much light" for that close of an object.
I would think that a "simple fix" would be to BLOCK some of the LEDs - until you get less washout, and overall better "contrast" of the thermometer dial.
It may take some trial and error, but you may want to try a few pieces of BLACK electrical tape - cut and placed OVER the LEDs around the face of the camera. Note NOT to cover the "light sensor" - usually mounted at the TOP of the camera face.
NOTE: This lower lighting level MAY cause loss of detail in the surrounding areas, but if the temperature monitoring is the main purpose of this camera, that should not be a concern.
Please give this blocking of the LEDs a try, and let me know your results or if you have any more questions.
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