FLIR Lepton Adapter

The FLIR Lepton Adapter Module connects FLIR Lepton thermal cores (sold separately) to the OpenMV Cam, with both AGC and direct-thermal modes for human / object temperature measurement.

FLIR Lepton Adapter

For full datasheet, photos, and ordering see the FLIR Lepton Adapter product page.

Highlights

  • Compatible with FLIR Lepton 1.x / 2.x / 3.x cores (sold separately)

  • Both AGC and direct-thermal modes with temperature mapping

  • Sees in total darkness

  • Compatible with all modular OpenMV Cam base boards

Usage

Drive the Lepton through csi.CSI with cid= csi.LEPTON. The driver internally upscales the Lepton’s 80x60 (1.x/2.x) or 160x120 (3.x) native frame to whatever framesize you set:

import csi
import time

csi0 = csi.CSI(cid=csi.LEPTON)
csi0.reset()
csi0.pixformat(csi.GRAYSCALE)
csi0.framesize(csi.QVGA)
clock = time.clock()

while True:
    clock.tick()
    img = csi0.snapshot()
    print(clock.fps())

To get colorized frames straight from the sensor, switch the pixformat to csi.RGB565 and set csi.CSI.color_palette to image.PALETTE_IRONBOW — the driver emits RGB565 frames with the palette applied, so snapshot() returns ironbow-colored frames directly:

csi0.pixformat(csi.RGB565)
csi0.color_palette(image.PALETTE_IRONBOW)

Temperature measurement

Radiometric Leptons (Lepton 2.5 / 3.5) report calibrated per-pixel temperature data. Enable measurement mode through csi.CSI.ioctl with csi.IOCTL_LEPTON_SET_MODE, then clamp the temperature window with csi.IOCTL_LEPTON_SET_RANGE (min_celsius, max_celsius). The Lepton driver linearly maps grayscale pixel value 0 to min_celsius and 255 to max_celsius, so each pixel becomes a temperature lookup within the configured window. Pixels colder than min_celsius saturate at 0, pixels hotter than max_celsius saturate at 255.

csi.IOCTL_LEPTON_SET_MODE takes two flags. The first turns measurement on; the second selects the sensor’s temperature range:

  • Low range — (True, False) — sensor span -10 °C to +140 °C (room-scale scenes). Clamp the window to the area of interest, e.g. (20.0, 40.0) for body-heat tracking:

    csi0.ioctl(csi.IOCTL_LEPTON_SET_MODE, True, False)
csi0.ioctl(csi.IOCTL_LEPTON_SET_RANGE, 20.0, 40.0)

  • High range — (True, True) — sensor span -10 °C to ~+450 °C typical (~+400 °C at room temperature) for hot objects. Clamp to e.g. (0.0, 400.0) for furnace or hot-element tracking:

    csi0.ioctl(csi.IOCTL_LEPTON_SET_MODE, True, True)
csi0.ioctl(csi.IOCTL_LEPTON_SET_RANGE, 0.0, 400.0)

To convert a grayscale pixel back to Celsius:

def p_to_temp(p, min_t, max_t):
    return (p * (max_t - min_t)) / 255.0 + min_t

This works on individual pixels or on aggregated statistics (e.g. stats.mean() from Image.get_statistics) inside an ROI when locating hot/cool regions with Image.find_blobs.

Note

Temperature measurement requires the Lepton in grayscale mode with no color palette set — the linear pixel-to-temperature mapping only holds on the raw grayscale output. To colorize for display, do it separately by drawing the grayscale frame onto an RGB output buffer with Image.draw_image and color_palette= image.PALETTE_IRONBOW:

out = image.Image(csi0.width(), csi0.height(), image.RGB565)
out.draw_image(img, 0, 0, color_palette=image.PALETTE_IRONBOW)