Add example for PIL image save

examples/mlx90640_pil.py

@@ -0,0 +1,86 @@
+"""This example is for Raspberry Pi (Linux) only!
+   It will not work on microcontrollers running CircuitPython!"""
+
+import math
+import board
+import adafruit_mlx90640
+from PIL import Image
+
+FILENAME = "mlx.jpg"
+
+MINTEMP = 25.0  # low range of the sensor (deg C)
+MAXTEMP = 45.0  # high range of the sensor (deg C)
+COLORDEPTH = 1000  # how many color values we can have
+INTERPOLATE = 10  # scale factor for final image
+
+mlx = adafruit_mlx90640.MLX90640(board.I2C())
+
+# the list of colors we can choose from
+heatmap = (
+    (0.0, (0, 0, 0)),
+    (0.20, (0, 0, 0.5)),
+    (0.40, (0, 0.5, 0)),
+    (0.60, (0.5, 0, 0)),
+    (0.80, (0.75, 0.75, 0)),
+    (0.90, (1.0, 0.75, 0)),
+    (1.00, (1.0, 1.0, 1.0)),
+)
+
+colormap = [0] * COLORDEPTH
+
+# some utility functions
+def constrain(val, min_val, max_val):
+    return min(max_val, max(min_val, val))
+
+
+def map_value(x, in_min, in_max, out_min, out_max):
+    return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min
+
+
+def gaussian(x, a, b, c, d=0):
+    return a * math.exp(-((x - b) ** 2) / (2 * c ** 2)) + d
+
+
+def gradient(x, width, cmap, spread=1):
+    width = float(width)
+    r = sum(
+        [gaussian(x, p[1][0], p[0] * width, width / (spread * len(cmap))) for p in cmap]
+    )
+    g = sum(
+        [gaussian(x, p[1][1], p[0] * width, width / (spread * len(cmap))) for p in cmap]
+    )
+    b = sum(
+        [gaussian(x, p[1][2], p[0] * width, width / (spread * len(cmap))) for p in cmap]
+    )
+    r = int(constrain(r * 255, 0, 255))
+    g = int(constrain(g * 255, 0, 255))
+    b = int(constrain(b * 255, 0, 255))
+    return r, g, b
+
+
+for i in range(COLORDEPTH):
+    colormap[i] = gradient(i, COLORDEPTH, heatmap)
+
+# get sensor data
+frame = [0] * 768
+success = False
+while not success:
+    try:
+        mlx.getFrame(frame)
+        success = True
+    except ValueError:
+        continue
+
+# create the image
+pixels = [0] * 768
+for i, pixel in enumerate(frame):
+    coloridx = map_value(pixel, MINTEMP, MAXTEMP, 0, COLORDEPTH - 1)
+    coloridx = int(constrain(coloridx, 0, COLORDEPTH - 1))
+    pixels[i] = colormap[coloridx]
+
+# save to file
+img = Image.new("RGB", (32, 24))
+img.putdata(pixels)
+img = img.transpose(Image.FLIP_TOP_BOTTOM)
+img = img.resize((32 * INTERPOLATE, 24 * INTERPOLATE), Image.BICUBIC)
+img.save("ir.jpg")