关于人脸检测矩形框不准或不显示的问题

[lg1h]

import sensor,image,time



sensor.reset() # Initialize the camera sensor.
sensor.set_contrast(1)
sensor.set_gainceiling(16)
sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.HQVGA) # or sensor.QQVGA (or others)
sensor.skip_frames(time = 2000) # Let new settings take affect.

# Load up a face detection HaarCascade. This is object that your OpenMV Cam
# can use to detect faces using the find_features() method below. Your OpenMV
# Cam has fontalface HaarCascade built-in. By default, all the stages of the
# HaarCascade are loaded. However, You can adjust the number of stages to speed
# up processing at the expense of accuracy. The frontalface HaarCascade has 25
# stages.
face_cascade = image.HaarCascade("frontalface", stages=25)
print(face_cascade)
while(True):
    img = sensor.snapshot()
        # Threshold can be between 0.0 and 1.0. A higher threshold results in a
        # higher detection rate with more false positives. The scale value
        # controls the matching scale allowing you to detect smaller faces.
    faces = img.find_features(face_cascade, threshold=0.75, scale_factor=1.35)


    for r in faces:
        img.draw_rectangle(r)
    

尝试过更改stage,threshold和scale_factor，但无法像视频教程14那样持续且准确地框出人脸，stage偏大时无法显示矩形框，想请问是openmv自带模型的问题？摄像头的问题？计算机配置问题？还是其他问题？
print(face_cascade)在串行终端显示为"width":24, "height":24, "n_stages":25, "n_features":2913, "n_rectangles":6383

[kidswong999]

可能是光线不好，灯应该正对人脸，如果背对这光，脸就会黑。

你可以发个照片看一下。