This page describes how to interpret the raw data files (*.DAT), which are created by the device for each saved image and video / time-lapse frame on the internal storage.

A sample .DAT file can be found here with the corresponding thermal images linked here.

The structure of the DAT file is define as following - see “method “SaveRawData” here as reference:

  • Lepton raw values - 9600 byte (Lepton2) or 38400 byte (Lepton3)

    • 4800 / 19200 raw values for the Lepton2 / Lepton3, split to two bytes, MSB first, then LSB
    • Raw value is 14-bit (0 … 16383) for each pixel, equivalent to infrared intensity
    • Difference can be made by the total file size (10005 byte Lepton2 vs. 38805 Lepton3)
  • Minimum temp - 2 byte

    • 14-bit minimum raw value to apply the color scheme, could be fixed if in manual mode o Split to two bytes, MSB first, then LSB. Reconstruction analog to the lepton raw values
  • Maximum temp - 2 byte

    • 14-bit maximum raw value, same format than the minimum temperature value
  • Spot sensor temp - 4 byte

    • Object temperature measured by the spot sensor; Float, split to four bytes, LSB first
    • Format is Celsius or Fahrenheit, depending on the set temperature format
  • Color scheme - 1 byte

    • Number of the color scheme, the image was created with
    • Number definitions can be looked up in this file under "Color scheme numbers"
  • Temperature format - 1 byte

    • The temperature format is applied to all absolute temperatures
    • Celsius (0) or Fahrenheit (1)
  • Show spot - 1 byte

    • Display the MLX90614 spot temperature information in an image or not
    • Disabled (0) or Enabled (1)
  • Show color bar - 1 byte

    • Display the radiometric color bar in an image or not
    • Disabled (0) or Enabled (1)
  • Show minimum / maximum point - 1 byte

    • Show the minimum and / or maximum temperature point(s) in an image or not
    • Disabled (0), Min only (1), Max only (2), Min & Max (3)
  • Calibration offset - 4 byte

    • Offset for the raw-to-abs temperature conversion
    • Float, split to four bytes, LSB first. Reconstruction analog to the spot sensor temp
  • Calibration slope - 4 byte

    • Slope for the raw-to-abs temperature conversion
    • Float, split to four bytes, LSB first. Reconstruction analog to the spot sensor temp

The absolute temperature can be calculated out of each raw value by using the following formula: absTemp = rawValue * calibrationSlope + calibrationOffset

  • Temperature points - 384 byte

    • 96 different temperature points, containing the index position and lepton raw value
    • They are manually defined by the user and could be skipped if not utilized
    • The first two bytes are the index position, second two bytes are the lepton raw value
    • Index position: (0,0) = 1; (159, 119) = 19200; 0 = not set, otherwise set; MSB first, then LSB