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RE 14bit grey scale (one more time)

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This topic contains 4 replies, has 1 voice, and was last updated by Profile photo of Antone Antone 12 months ago.

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  • #16310

    Profile photo of Antone
    Antone

    Participant

    How to interpret 14/16bit greyscale data and a question.

    Ok so currently I’m using a raspberry pi 3b+ with a Lepton 3.5 connected to a PureThermal2.

    My team and I, finally figured out how to grab “14bit” 16bit grey scale images using gstreamer.

    We didn’t know what to make of the pixel values.

    At first the assumption was that the 14bit data was 2’s compliment and shifted up by 2bits making the first two Least sig bits unused. that would give us a range of 8191 values * 50m°K giving a range of (409.55°C -10°C) giving a range of -10°C to 400°C.
    Makes sense it covers the advertised range; however, the values did not work out at all trying to use that method.

    Doing some hunting on forums I found some information about Plank’s law and creating a best fit curve, to get the temperature of the object, and spent some time trying to figure out how exactly to do that

    #16311

    Profile photo of Antone
    Antone

    Participant

    Apparently the values are simply encoded as (degrees Kelvin) * 100 for radiometric data, which is extremely simple. To attain measured values in C simply take (16bit pixel value)/100 – 273.15°K and it works. I have not been able to find this in any of the literature on the Lepton cameras. I verified the conversions using a thermos of hot water, a container of ice water and my hand. All checked with a temperature gun.

    #16312

    Profile photo of Antone
    Antone

    Participant

    This is absolutely maddening, I’m trying to link the google group that I found the information in and the how I was able to collect 14 grey scale stills with Gstreamer…

    What is going on with this forum?

    #16313

    Profile photo of Antone
    Antone

    Participant

    Problem/Question:
    I found out the hard way that the lepton is defaulted to high gain mode, giving me a maximum value of 45395, 453.96°K or 180°C.

    I would like to operate in low gain mode.
    Is there any easy way to get the purethermal2 to boot in low gain mode?
    Is there a command for gstreamer that will initialize me in low gain mode?

    I’ve looked at some of the more feature rich python libraries for the purethermal2, but they are very resource inefficient at idle using over 25% of my Rpi CPU.

    Are there any good c/c++ libraries that work with the PureThermal2?
    I may be able to write my own custom code with the gstreamer library if I am able to get the purethermal2 to operate in low gain mode.

    Thanks for any help.
    Antone-

    #16314

    Profile photo of Antone
    Antone

    Participant

    PS why aren’t we allowed to post links, or terminal commands?
    This makes communication difficult?

    This wouldn’t be so incredibly frustrating except I’ve had to redo this multiple times now.
    not getting any useful information about what in my post was being rejected.

    I have other studying to do, I would just like to share what I learned and see if I can get help with my questions.

    • This reply was modified 12 months ago by Profile photo of Antone Antone. Reason: frustration

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