Python Opencv 将 numpy.zeros 绘制为灰度图像
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Opencv draws numpy.zeros as a gray image
提问by Vanuan
I'm struggling with understanding how opencv interprets numpy arrays.
我正在努力理解 opencv 如何解释 numpy 数组。
import cv2
import numpy as np
if __name__ == '__main__':
size = (w, h, channels) = (100, 100, 1)
img = np.zeros(size, np.int8)
cv2.imshow('result', img), cv2.waitKey(0)
cv2.destroyAllWindows()
Grayscale black 100x100 image, right? No, it's showing me gray! Why's that?
灰度黑色 100x100 图像，对吗？不，它显示我是灰色的！为什么？
回答by Vanuan
Ok, the crucial part is dtype. I've chosen np.int8. When I use np.uint8, it is black.
好的，关键部分是 dtype。我选择了np.int8。当我使用时np.uint8，它是黑色的。
Suprisingly, when dtype=np.int8, zeros are interpreted as 127(or 128)!
令人惊讶的是，当dtype=np.int8，零被解释为 127（或 128）！
I expected that zero is still zero, no matter if it is signed or unsigned.
我预计零仍然为零，无论它是有符号还是无符号。
回答by Mateen Ulhaq
For a BGR image,
对于 BGR 图像，
img = np.zeros([height, width, 3], dtype=np.uint8)
