https://blog.csdn.net/qq_19707521/article/details/78361600
https://blog.csdn.net/qq_30815237/article/details/88665822
https://www.cnblogs.com/zxy-joy/p/10687152.html
二值化参数:
thresholdType:Int类型的
THRESH_BINARY 二进制阈值化 -> 大于阈值为1 小于阈值为0
THRESH_BINARY_INV 反二进制阈值化 -> 大于阈值为0 小于阈值为1
THRESH_TRUNC 截断阈值化 -> 大于阈值为阈值,小于阈值不变
THRESH_TOZERO 阈值化为0 -> 大于阈值的不变,小于阈值的全为0
THRESH_TOZERO_INV 反阈值化为0 -> 大于阈值为0,小于阈值不变