识别所有接近z的值

Question

我有一个numpy数组，我从数组中减去一个常量值。如果需要的话，我希望值变为负数（而不是环绕或楼层为零）。然后我需要提取所有在零附近的数组值，并生成一个新的二进制数组/图像。因此，结果图像将显示接近于零的区域中的白色。你知道吗

我试图实现这个，但它的黑客，我不知道它是否正确。你能帮我做上面的事吗？你知道吗

# roi is a numpy array/image in Cielab colour space
swatch_colour = (255, 10, 30) # Cielab colour space
swatch_roi = np.full((roi.shape[0], roi.shape[1], 3), swatch_colour, dtype='int8')
int_roi = roi.astype('int8')
diff = np.subtract(int_roi, swatch_roi)

thresh = diff.copy()
# Get all pixels whose Cielab colour is close to zero
thresh[np.abs(thresh) < (12,6,12)] = 0
# the remaining pixels are greater than/less than the above threshold
thresh[np.abs(thresh) > (0,0,0)] = 255

thresh = thresh.astype('uint8')
# convert from 3 channels to 1 channel
thresh = cv2.cvtColor(thresh, cv2.COLOR_BGR2GRAY)
# Invert the image so that the pixels that were close to zero are white
thresh = cv2.bitwise_not(thresh)

Answer 1

Numpy可以索引切片逻辑运算符

你为什么能这样做？你知道吗

image[image.logical_and( image > -05 , image < 05 )]

https://docs.scipy.org/doc/numpy/reference/generated/numpy.logical_and.html