python opencv imread(filename, flags=None) 读取图像 flags cv::ImreadModes 参数上哪看去？
在调用opencv的imread(filename, flags=None)函数时，后面有个flags=None参数，但打开文档轻描淡写，不知该参数上哪找去，用全局搜索也搜不到，莫非要到官网查？（擦汗’’）
打开官网，有个Online documentation，点它:
然后找到自己opencv版本点进去，我的是这个（如果不知道自己opencv版本可以在控制台执行pip list查看）：
点进去后右上角搜索就ok了：
IMREAD_UNCHANGED
Python: cv.IMREAD_UNCHANGED
If set, return the loaded image as is (with alpha channel, otherwise it gets cropped).
IMREAD_GRAYSCALE
Python: cv.IMREAD_GRAYSCALE
If set, always convert image to the single channel grayscale image (codec internal conversion).
IMREAD_COLOR
Python: cv.IMREAD_COLOR
If set, always convert image to the 3 channel BGR color image.
IMREAD_ANYDEPTH
Python: cv.IMREAD_ANYDEPTH
If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
IMREAD_ANYCOLOR
Python: cv.IMREAD_ANYCOLOR
If set, the image is read in any possible color format.
IMREAD_LOAD_GDAL
Python: cv.IMREAD_LOAD_GDAL
If set, use the gdal driver for loading the image.
IMREAD_REDUCED_GRAYSCALE_2
Python: cv.IMREAD_REDUCED_GRAYSCALE_2
If set, always convert image to the single channel grayscale image and the image size reduced 1/2.
IMREAD_REDUCED_COLOR_2
Python: cv.IMREAD_REDUCED_COLOR_2
If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.
IMREAD_REDUCED_GRAYSCALE_4
Python: cv.IMREAD_REDUCED_GRAYSCALE_4
If set, always convert image to the single channel grayscale image and the image size reduced 1/4.
IMREAD_REDUCED_COLOR_4
Python: cv.IMREAD_REDUCED_COLOR_4
If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.
IMREAD_REDUCED_GRAYSCALE_8
Python: cv.IMREAD_REDUCED_GRAYSCALE_8
If set, always convert image to the single channel grayscale image and the image size reduced 1/8.
IMREAD_REDUCED_COLOR_8
Python: cv.IMREAD_REDUCED_COLOR_8
If set, always convert image to the 3 channel BGR color image and the image size reduced 1/8.
IMREAD_IGNORE_ORIENTATION
Python: cv.IMREAD_IGNORE_ORIENTATION
If set, do not rotate the image according to EXIF's orientation flag.
参考文章：python opencv imread()函数 （从文件加载图像）