opencv 10 -- 图像 颜色空间转换

颜色空间，常见的有三种模式：

灰色图 BGR HSV

备注：在opencv里面，BGR，这个顺序要注意的，常见的是RGB的称呼

经常用到的 两种：BGR↔Gray 和 BGR↔HSV

函数是：cv2.cvtColor(input_image ，flag)， 其中 flag是转换类型

对于 BGR↔Gray 的转换，使用的 flag 就是 cv2.COLOR_BGR2GRAY 对于 BGR↔HSV 的转换，我们用的 flag 就是 cv2.COLOR_BGR2HSV

注意：在 OpenCV 的 HSV 格式中， H（色彩/色度）的取值范围是 [0，179]， S（饱和度）的取值范围 [0，255]， V（亮度）的取值范围 [0，255] 但是不同的软件使用的值可能不同 ，需要归一化

打印所有的flag

import cv2

for i in dir(cv2) :
	if i.startswith('COLOR_'):
		print (i)

结果： COLOR_BAYER_BG2BGR COLOR_BAYER_BG2BGRA COLOR_BAYER_BG2BGR_EA COLOR_BAYER_BG2BGR_VNG COLOR_BAYER_BG2GRAY COLOR_BAYER_BG2RGB COLOR_BAYER_BG2RGBA COLOR_BAYER_BG2RGB_EA COLOR_BAYER_BG2RGB_VNG COLOR_BAYER_GB2BGR COLOR_BAYER_GB2BGRA COLOR_BAYER_GB2BGR_EA COLOR_BAYER_GB2BGR_VNG COLOR_BAYER_GB2GRAY COLOR_BAYER_GB2RGB COLOR_BAYER_GB2RGBA COLOR_BAYER_GB2RGB_EA COLOR_BAYER_GB2RGB_VNG COLOR_BAYER_GR2BGR COLOR_BAYER_GR2BGRA COLOR_BAYER_GR2BGR_EA COLOR_BAYER_GR2BGR_VNG COLOR_BAYER_GR2GRAY COLOR_BAYER_GR2RGB COLOR_BAYER_GR2RGBA COLOR_BAYER_GR2RGB_EA COLOR_BAYER_GR2RGB_VNG COLOR_BAYER_RG2BGR COLOR_BAYER_RG2BGRA COLOR_BAYER_RG2BGR_EA COLOR_BAYER_RG2BGR_VNG COLOR_BAYER_RG2GRAY COLOR_BAYER_RG2RGB COLOR_BAYER_RG2RGBA COLOR_BAYER_RG2RGB_EA COLOR_BAYER_RG2RGB_VNG COLOR_BGR2BGR555 COLOR_BGR2BGR565 COLOR_BGR2BGRA COLOR_BGR2GRAY COLOR_BGR2HLS COLOR_BGR2HLS_FULL COLOR_BGR2HSV COLOR_BGR2HSV_FULL COLOR_BGR2LAB COLOR_BGR2LUV COLOR_BGR2Lab COLOR_BGR2Luv COLOR_BGR2RGB COLOR_BGR2RGBA COLOR_BGR2XYZ COLOR_BGR2YCR_CB COLOR_BGR2YCrCb COLOR_BGR2YUV COLOR_BGR2YUV_I420 COLOR_BGR2YUV_IYUV COLOR_BGR2YUV_YV12 COLOR_BGR5552BGR COLOR_BGR5552BGRA COLOR_BGR5552GRAY COLOR_BGR5552RGB COLOR_BGR5552RGBA COLOR_BGR5652BGR COLOR_BGR5652BGRA COLOR_BGR5652GRAY COLOR_BGR5652RGB COLOR_BGR5652RGBA COLOR_BGRA2BGR COLOR_BGRA2BGR555 COLOR_BGRA2BGR565 COLOR_BGRA2GRAY COLOR_BGRA2RGB COLOR_BGRA2RGBA COLOR_BGRA2YUV_I420 COLOR_BGRA2YUV_IYUV COLOR_BGRA2YUV_YV12 COLOR_BayerBG2BGR COLOR_BayerBG2BGRA COLOR_BayerBG2BGR_EA COLOR_BayerBG2BGR_VNG COLOR_BayerBG2GRAY COLOR_BayerBG2RGB COLOR_BayerBG2RGBA COLOR_BayerBG2RGB_EA COLOR_BayerBG2RGB_VNG COLOR_BayerGB2BGR COLOR_BayerGB2BGRA COLOR_BayerGB2BGR_EA COLOR_BayerGB2BGR_VNG COLOR_BayerGB2GRAY COLOR_BayerGB2RGB COLOR_BayerGB2RGBA COLOR_BayerGB2RGB_EA COLOR_BayerGB2RGB_VNG COLOR_BayerGR2BGR COLOR_BayerGR2BGRA COLOR_BayerGR2BGR_EA COLOR_BayerGR2BGR_VNG COLOR_BayerGR2GRAY COLOR_BayerGR2RGB COLOR_BayerGR2RGBA COLOR_BayerGR2RGB_EA COLOR_BayerGR2RGB_VNG COLOR_BayerRG2BGR COLOR_BayerRG2BGRA COLOR_BayerRG2BGR_EA COLOR_BayerRG2BGR_VNG COLOR_BayerRG2GRAY COLOR_BayerRG2RGB COLOR_BayerRG2RGBA COLOR_BayerRG2RGB_EA COLOR_BayerRG2RGB_VNG COLOR_COLORCVT_MAX COLOR_GRAY2BGR COLOR_GRAY2BGR555 COLOR_GRAY2BGR565 COLOR_GRAY2BGRA COLOR_GRAY2RGB COLOR_GRAY2RGBA COLOR_HLS2BGR COLOR_HLS2BGR_FULL COLOR_HLS2RGB COLOR_HLS2RGB_FULL COLOR_HSV2BGR COLOR_HSV2BGR_FULL COLOR_HSV2RGB COLOR_HSV2RGB_FULL COLOR_LAB2BGR COLOR_LAB2LBGR COLOR_LAB2LRGB COLOR_LAB2RGB COLOR_LBGR2LAB COLOR_LBGR2LUV COLOR_LBGR2Lab COLOR_LBGR2Luv COLOR_LRGB2LAB COLOR_LRGB2LUV COLOR_LRGB2Lab COLOR_LRGB2Luv COLOR_LUV2BGR COLOR_LUV2LBGR COLOR_LUV2LRGB COLOR_LUV2RGB COLOR_Lab2BGR COLOR_Lab2LBGR COLOR_Lab2LRGB COLOR_Lab2RGB COLOR_Luv2BGR COLOR_Luv2LBGR COLOR_Luv2LRGB COLOR_Luv2RGB COLOR_M_RGBA2RGBA COLOR_RGB2BGR COLOR_RGB2BGR555 COLOR_RGB2BGR565 COLOR_RGB2BGRA COLOR_RGB2GRAY COLOR_RGB2HLS COLOR_RGB2HLS_FULL COLOR_RGB2HSV COLOR_RGB2HSV_FULL COLOR_RGB2LAB COLOR_RGB2LUV COLOR_RGB2Lab COLOR_RGB2Luv COLOR_RGB2RGBA COLOR_RGB2XYZ COLOR_RGB2YCR_CB COLOR_RGB2YCrCb COLOR_RGB2YUV COLOR_RGB2YUV_I420 COLOR_RGB2YUV_IYUV COLOR_RGB2YUV_YV12 COLOR_RGBA2BGR COLOR_RGBA2BGR555 COLOR_RGBA2BGR565 COLOR_RGBA2BGRA COLOR_RGBA2GRAY COLOR_RGBA2M_RGBA COLOR_RGBA2RGB COLOR_RGBA2YUV_I420 COLOR_RGBA2YUV_IYUV COLOR_RGBA2YUV_YV12 COLOR_RGBA2mRGBA COLOR_XYZ2BGR COLOR_XYZ2RGB COLOR_YCR_CB2BGR COLOR_YCR_CB2RGB COLOR_YCrCb2BGR COLOR_YCrCb2RGB COLOR_YUV2BGR COLOR_YUV2BGRA_I420 COLOR_YUV2BGRA_IYUV COLOR_YUV2BGRA_NV12 COLOR_YUV2BGRA_NV21 COLOR_YUV2BGRA_UYNV COLOR_YUV2BGRA_UYVY COLOR_YUV2BGRA_Y422 COLOR_YUV2BGRA_YUNV COLOR_YUV2BGRA_YUY2 COLOR_YUV2BGRA_YUYV COLOR_YUV2BGRA_YV12 COLOR_YUV2BGRA_YVYU COLOR_YUV2BGR_I420 COLOR_YUV2BGR_IYUV COLOR_YUV2BGR_NV12 COLOR_YUV2BGR_NV21 COLOR_YUV2BGR_UYNV COLOR_YUV2BGR_UYVY COLOR_YUV2BGR_Y422 COLOR_YUV2BGR_YUNV COLOR_YUV2BGR_YUY2 COLOR_YUV2BGR_YUYV COLOR_YUV2BGR_YV12 COLOR_YUV2BGR_YVYU COLOR_YUV2GRAY_420 COLOR_YUV2GRAY_I420 COLOR_YUV2GRAY_IYUV COLOR_YUV2GRAY_NV12 COLOR_YUV2GRAY_NV21 COLOR_YUV2GRAY_UYNV COLOR_YUV2GRAY_UYVY COLOR_YUV2GRAY_Y422 COLOR_YUV2GRAY_YUNV COLOR_YUV2GRAY_YUY2 COLOR_YUV2GRAY_YUYV COLOR_YUV2GRAY_YV12 COLOR_YUV2GRAY_YVYU COLOR_YUV2RGB COLOR_YUV2RGBA_I420 COLOR_YUV2RGBA_IYUV COLOR_YUV2RGBA_NV12 COLOR_YUV2RGBA_NV21 COLOR_YUV2RGBA_UYNV COLOR_YUV2RGBA_UYVY COLOR_YUV2RGBA_Y422 COLOR_YUV2RGBA_YUNV COLOR_YUV2RGBA_YUY2 COLOR_YUV2RGBA_YUYV COLOR_YUV2RGBA_YV12 COLOR_YUV2RGBA_YVYU COLOR_YUV2RGB_I420 COLOR_YUV2RGB_IYUV COLOR_YUV2RGB_NV12 COLOR_YUV2RGB_NV21 COLOR_YUV2RGB_UYNV COLOR_YUV2RGB_UYVY COLOR_YUV2RGB_Y422 COLOR_YUV2RGB_YUNV COLOR_YUV2RGB_YUY2 COLOR_YUV2RGB_YUYV COLOR_YUV2RGB_YV12 COLOR_YUV2RGB_YVYU COLOR_YUV420P2BGR COLOR_YUV420P2BGRA COLOR_YUV420P2GRAY COLOR_YUV420P2RGB COLOR_YUV420P2RGBA COLOR_YUV420SP2BGR COLOR_YUV420SP2BGRA COLOR_YUV420SP2GRAY COLOR_YUV420SP2RGB COLOR_YUV420SP2RGBA COLOR_YUV420p2BGR COLOR_YUV420p2BGRA COLOR_YUV420p2GRAY COLOR_YUV420p2RGB COLOR_YUV420p2RGBA COLOR_YUV420sp2BGR COLOR_YUV420sp2BGRA COLOR_YUV420sp2GRAY COLOR_YUV420sp2RGB COLOR_YUV420sp2RGBA COLOR_mRGBA2RGBA

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