Automatic Grayscale Color Tracking - 自动灰度颜色追踪

# 自动灰度颜色追踪例程
#
# 这个例子展示了使用CanMV的单色自动灰度色彩跟踪。

import sensor, image, time
print("Letting auto algorithms run. Don't put anything in front of the camera!")

sensor.reset()
sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.QVGA)
sensor.skip_frames(time = 2000)
sensor.set_auto_gain(False) # 颜色跟踪必须自动增益
sensor.set_auto_whitebal(False) # 颜色跟踪必须关闭白平衡
clock = time.clock()

# Capture the color thresholds for whatever was in the center of the image.
r = [(320//2)-(50//2), (240//2)-(50//2), 50, 50] # 50x50 center of QVGA.

print("Auto algorithms done. Hold the object you want to track in front of the camera in the box.")
print("MAKE SURE THE COLOR OF THE OBJECT YOU WANT TO TRACK IS FULLY ENCLOSED BY THE BOX!")
for i in range(60):
    img = sensor.snapshot()
    img.draw_rectangle(r)

print("Learning thresholds...")
threshold = [128, 128] # Middle grayscale values. 中间灰度值。
for i in range(60):
    img = sensor.snapshot()
    hist = img.get_histogram(roi=r)
    lo = hist.get_percentile(0.01) # 获取1％范围的直方图的CDF（根据需要调整）！
    hi = hist.get_percentile(0.99) # 获取99％范围的直方图的CDF（根据需要调整）！
    # 平均百分位值。
    threshold[0] = (threshold[0] + lo.value()) // 2
    threshold[1] = (threshold[1] + hi.value()) // 2
    for blob in img.find_blobs([threshold], pixels_threshold=100, area_threshold=100, merge=True, margin=10):
        img.draw_rectangle(blob.rect())
        img.draw_cross(blob.cx(), blob.cy())
        img.draw_rectangle(r)

print("Thresholds learned...")
print("Tracking colors...")

while(True):
    clock.tick()
    img = sensor.snapshot()
    for blob in img.find_blobs([threshold], pixels_threshold=100, area_threshold=100, merge=True, margin=10):
        img.draw_rectangle(blob.rect())
        img.draw_cross(blob.cx(), blob.cy())
    print(clock.fps())

具体接口定义请参考 find_blobs