How do pixel values relate to gain exactly?

MJ

• September 13, 2024 14:06

I am using FlyCapture2 SDK with a Blackfly GigE camera. I am experimenting with the "gain" setting. In "absolute" mode, the gain ranges from -1.5 dB to 40.5 dB. When I take a series of images of a uniform-color field at increasing gain values in that range, I see that the average pixel value grows at what appears to be an exponential rate. What rate is this exactly? That is, what is the definition of the dB that "gain" represents? If dB = 20 * log(V/V0), where V0 is the input voltage at gain = 0, then I would expect the average pixel values to increase faster than I'm measuring. For example, if I measure an average pixel value of ~19 at gain = 0, I would expect the average pixel value as a function of gain (g) to be = 19 * 10^(g/20), but that curve is steeper than what I measure. Here is a plot:

 

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  TDY_Manuel

  Community team

  • September 17, 2024 07:45

  

  Hello MJ, 
  
  You are right, we use a 20 log rule for our gain setting. I'm wondering if the Brightness setting could cause this. Could you please check if it was set to 0? 

   

  Best regards,

  Manuel  

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