Summary: As we all know, computer vision ( Computer Version short for CV) is a major research direction in the development of artificial intelligence and robotics, and opencv is a third party that provides technical and functional support for computer vision programming. The library is naturally a content that needs to be studied. The function to be introduced in this issue is the function under the opencv library - cvtColor(). The main function of this function is to convert the image from one color space to another ( that is, to switch the filter ). Usually, we need to convert the image from the RGB space to another color space so that we can process the image. Corresponding analysis and processing. ( It’s just a layer of vest, so that people can get to know each other )
This article still invites my favorite character "robot" in "Famine" ( robot: I have a name, my name is WX-78 ). When he picks up gears and doesn't pay attention, we use him as our The material, as shown in the picture below ( WX-78: Damn, young people don’t talk about martial arts, come to cheat, come and attack my little comrade with 100 drops of blood ). Without further ado, I am Mr. Kamen Black, and I will start today's study immediately . I can't wait .
Text content:
print("祝大家每天快乐，love and peace！")① Preparation for use:
Same as the previous two issues, we still call our old partner of the toolman - opencv, as the major premise for us to use cvtcolor.
import cv2②Grammar description:
dst=cv2.cvtColor(src,code[, dst[, dstCn]])
Among them, dst (destination) means the destination image we get after function processing, which is in matrix form at this time;
src(source) indicates the source image object we want to convert, also in matrix form;
code is a macro constant defined by the color space in opencv, which shows the results we want to achieve for image conversion. Commonly used are COLOR_BGR2GRAY, COLOR_GRAY2BGR, COLOR_BGR2HSV, COLOR_BGR2RGB, etc., but in fact there are as many as 247 parameters that can be called. (Statistics in version 4.5.2) ( Just like those rich people on the Forbes list, the wealth they use only accounts for a small part of their net worth, and it is mainly used as a display of strength );
dstCn is the channel number of the target image, if it is set to 0, it will automatically calculate the channel number of the target image from the source image;
The parameters of the code are shown below for your reference and learning ( to understand the importance of ctrl+F ):
| cv::ColorConversionCodes | cv::COLOR_BGR2BGRA = 0, cv::COLOR_RGB2RGBA = COLOR_BGR2BGRA, cv::COLOR_BGRA2BGR = 1, cv::COLOR_RGBA2RGB = COLOR_BGRA2BGR, cv::COLOR_BGR2RGBA = 2, cv::COLOR_RGB2BGRA = COLOR_BGR2RGBA, cv::COLOR_RGBA2BGR = 3, cv::COLOR_BGRA2RGB = COLOR_RGBA2BGR, cv::COLOR_BGR2RGB = 4, cv::COLOR_RGB2BGR = COLOR_BGR2RGB, cv::COLOR_BGRA2RGBA = 5, cv::COLOR_RGBA2BGRA = COLOR_BGRA2RGBA, cv::COLOR_BGR2GRAY = 6, cv::COLOR_RGB2GRAY = 7, cv::COLOR_GRAY2BGR = 8, cv::COLOR_GRAY2RGB = COLOR_GRAY2BGR, cv::COLOR_GRAY2BGRA = 9, cv::COLOR_GRAY2RGBA = COLOR_GRAY2BGRA, cv::COLOR_BGRA2GRAY = 10, cv::COLOR_RGBA2GRAY = 11, cv::COLOR_BGR2BGR565 = 12, cv::COLOR_RGB2BGR565 = 13, cv::COLOR_BGR5652BGR = 14, cv::COLOR_BGR5652RGB = 15, cv::COLOR_BGRA2BGR565 = 16, cv::COLOR_RGBA2BGR565 = 17, cv::COLOR_BGR5652BGRA = 18, cv::COLOR_BGR5652RGBA = 19, cv::COLOR_GRAY2BGR565 = 20, cv::COLOR_BGR5652GRAY = 21, cv::COLOR_BGR2BGR555 = 22, cv::COLOR_RGB2BGR555 = 23, cv::COLOR_BGR5552BGR = 24, cv::COLOR_BGR5552RGB = 25, cv::COLOR_BGRA2BGR555 = 26, cv::COLOR_RGBA2BGR555 = 27, cv::COLOR_BGR5552BGRA = 28, cv::COLOR_BGR5552RGBA = 29, cv::COLOR_GRAY2BGR555 = 30, cv::COLOR_BGR5552GRAY = 31, cv::COLOR_BGR2XYZ = 32, cv::COLOR_RGB2XYZ = 33, cv::COLOR_XYZ2BGR = 34, cv::COLOR_XYZ2RGB = 35, cv::COLOR_BGR2YCrCb = 36, cv::COLOR_RGB2YCrCb = 37, cv::COLOR_YCrCb2BGR = 38, cv::COLOR_YCrCb2RGB = 39, cv::COLOR_BGR2HSV = 40, cv::COLOR_RGB2HSV = 41, cv::COLOR_BGR2Lab = 44, cv::COLOR_RGB2Lab = 45, cv::COLOR_BGR2Luv = 50, cv::COLOR_RGB2Luv = 51, cv::COLOR_BGR2HLS = 52, cv::COLOR_RGB2HLS = 53, cv::COLOR_HSV2BGR = 54, cv::COLOR_HSV2RGB = 55, cv::COLOR_Lab2BGR = 56, cv::COLOR_Lab2RGB = 57, cv::COLOR_Luv2BGR = 58, cv::COLOR_Luv2RGB = 59, cv::COLOR_HLS2BGR = 60, cv::COLOR_HLS2RGB = 61, cv::COLOR_BGR2HSV_FULL = 66, cv::COLOR_RGB2HSV_FULL = 67, cv::COLOR_BGR2HLS_FULL = 68, cv::COLOR_RGB2HLS_FULL = 69, cv::COLOR_HSV2BGR_FULL = 70, cv::COLOR_HSV2RGB_FULL = 71, cv::COLOR_HLS2BGR_FULL = 72, cv::COLOR_HLS2RGB_FULL = 73, cv::COLOR_LBGR2Lab = 74, cv::COLOR_LRGB2Lab = 75, cv::COLOR_LBGR2Luv = 76, cv::COLOR_LRGB2Luv = 77, cv::COLOR_Lab2LBGR = 78, cv::COLOR_Lab2LRGB = 79, cv::COLOR_Luv2LBGR = 80, cv::COLOR_Luv2LRGB = 81, cv::COLOR_BGR2YUV = 82, cv::COLOR_RGB2YUV = 83, cv::COLOR_YUV2BGR = 84, cv::COLOR_YUV2RGB = 85, cv::COLOR_YUV2RGB_NV12 = 90, cv::COLOR_YUV2BGR_NV12 = 91, cv::COLOR_YUV2RGB_NV21 = 92, cv::COLOR_YUV2BGR_NV21 = 93, cv::COLOR_YUV420sp2RGB = COLOR_YUV2RGB_NV21, cv::COLOR_YUV420sp2BGR = COLOR_YUV2BGR_NV21, cv::COLOR_YUV2RGBA_NV12 = 94, cv::COLOR_YUV2BGRA_NV12 = 95, cv::COLOR_YUV2RGBA_NV21 = 96, cv::COLOR_YUV2BGRA_NV21 = 97, cv::COLOR_YUV420sp2RGBA = COLOR_YUV2RGBA_NV21, cv::COLOR_YUV420sp2BGRA = COLOR_YUV2BGRA_NV21, cv::COLOR_YUV2RGB_YV12 = 98, cv::COLOR_YUV2BGR_YV12 = 99, cv::COLOR_YUV2RGB_IYUV = 100, cv::COLOR_YUV2BGR_IYUV = 101, cv::COLOR_YUV2RGB_I420 = COLOR_YUV2RGB_IYUV, cv::COLOR_YUV2BGR_I420 = COLOR_YUV2BGR_IYUV, cv::COLOR_YUV420p2RGB = COLOR_YUV2RGB_YV12, cv::COLOR_YUV420p2BGR = COLOR_YUV2BGR_YV12, cv::COLOR_YUV2RGBA_YV12 = 102, cv::COLOR_YUV2BGRA_YV12 = 103, cv::COLOR_YUV2RGBA_IYUV = 104, cv::COLOR_YUV2BGRA_IYUV = 105, cv::COLOR_YUV2RGBA_I420 = COLOR_YUV2RGBA_IYUV, cv::COLOR_YUV2BGRA_I420 = COLOR_YUV2BGRA_IYUV, cv::COLOR_YUV420p2RGBA = COLOR_YUV2RGBA_YV12, cv::COLOR_YUV420p2BGRA = COLOR_YUV2BGRA_YV12, cv::COLOR_YUV2GRAY_420 = 106, cv::COLOR_YUV2GRAY_NV21 = COLOR_YUV2GRAY_420, cv::COLOR_YUV2GRAY_NV12 = COLOR_YUV2GRAY_420, cv::COLOR_YUV2GRAY_YV12 = COLOR_YUV2GRAY_420, cv::COLOR_YUV2GRAY_IYUV = COLOR_YUV2GRAY_420, cv::COLOR_YUV2GRAY_I420 = COLOR_YUV2GRAY_420, cv::COLOR_YUV420sp2GRAY = COLOR_YUV2GRAY_420, cv::COLOR_YUV420p2GRAY = COLOR_YUV2GRAY_420, cv::COLOR_YUV2RGB_UYVY = 107, cv::COLOR_YUV2BGR_UYVY = 108, cv::COLOR_YUV2RGB_Y422 = COLOR_YUV2RGB_UYVY, cv::COLOR_YUV2BGR_Y422 = COLOR_YUV2BGR_UYVY, cv::COLOR_YUV2RGB_UYNV = COLOR_YUV2RGB_UYVY, cv::COLOR_YUV2BGR_UYNV = COLOR_YUV2BGR_UYVY, cv::COLOR_YUV2RGBA_UYVY = 111, cv::COLOR_YUV2BGRA_UYVY = 112, cv::COLOR_YUV2RGBA_Y422 = COLOR_YUV2RGBA_UYVY, cv::COLOR_YUV2BGRA_Y422 = COLOR_YUV2BGRA_UYVY, cv::COLOR_YUV2RGBA_UYNV = COLOR_YUV2RGBA_UYVY, cv::COLOR_YUV2BGRA_UYNV = COLOR_YUV2BGRA_UYVY, cv::COLOR_YUV2RGB_YUY2 = 115, cv::COLOR_YUV2BGR_YUY2 = 116, cv::COLOR_YUV2RGB_YVYU = 117, cv::COLOR_YUV2BGR_YVYU = 118, cv::COLOR_YUV2RGB_YUYV = COLOR_YUV2RGB_YUY2, cv::COLOR_YUV2BGR_YUYV = COLOR_YUV2BGR_YUY2, cv::COLOR_YUV2RGB_YUNV = COLOR_YUV2RGB_YUY2, cv::COLOR_YUV2BGR_YUNV = COLOR_YUV2BGR_YUY2, cv::COLOR_YUV2RGBA_YUY2 = 119, cv::COLOR_YUV2BGRA_YUY2 = 120, cv::COLOR_YUV2RGBA_YVYU = 121, cv::COLOR_YUV2BGRA_YVYU = 122, cv::COLOR_YUV2RGBA_YUYV = COLOR_YUV2RGBA_YUY2, cv::COLOR_YUV2BGRA_YUYV = COLOR_YUV2BGRA_YUY2, cv::COLOR_YUV2RGBA_YUNV = COLOR_YUV2RGBA_YUY2, cv::COLOR_YUV2BGRA_YUNV = COLOR_YUV2BGRA_YUY2, cv::COLOR_YUV2GRAY_UYVY = 123, cv::COLOR_YUV2GRAY_YUY2 = 124, cv::COLOR_YUV2GRAY_Y422 = COLOR_YUV2GRAY_UYVY, cv::COLOR_YUV2GRAY_UYNV = COLOR_YUV2GRAY_UYVY, cv::COLOR_YUV2GRAY_YVYU = COLOR_YUV2GRAY_YUY2, cv::COLOR_YUV2GRAY_YUYV = COLOR_YUV2GRAY_YUY2, cv::COLOR_YUV2GRAY_YUNV = COLOR_YUV2GRAY_YUY2, cv::COLOR_RGBA2mRGBA = 125, cv::COLOR_mRGBA2RGBA = 126, cv::COLOR_RGB2YUV_I420 = 127, cv::COLOR_BGR2YUV_I420 = 128, cv::COLOR_RGB2YUV_IYUV = COLOR_RGB2YUV_I420, cv::COLOR_BGR2YUV_IYUV = COLOR_BGR2YUV_I420, cv::COLOR_RGBA2YUV_I420 = 129, cv::COLOR_BGRA2YUV_I420 = 130, cv::COLOR_RGBA2YUV_IYUV = COLOR_RGBA2YUV_I420, cv::COLOR_BGRA2YUV_IYUV = COLOR_BGRA2YUV_I420, cv::COLOR_RGB2YUV_YV12 = 131, cv::COLOR_BGR2YUV_YV12 = 132, cv::COLOR_RGBA2YUV_YV12 = 133, cv::COLOR_BGRA2YUV_YV12 = 134, cv::COLOR_BayerBG2BGR = 46, cv::COLOR_BayerGB2BGR = 47, cv::COLOR_BayerRG2BGR = 48, cv::COLOR_BayerGR2BGR = 49, cv::COLOR_BayerBG2RGB = COLOR_BayerRG2BGR, cv::COLOR_BayerGB2RGB = COLOR_BayerGR2BGR, cv::COLOR_BayerRG2RGB = COLOR_BayerBG2BGR , cv ::COLOR_BayerGR2RGB = COLOR_BayerGB2BG R, cv::COLOR_BayerBG2GRAY = 86, cv::COLOR_BayerGB2GRAY = 87, cv ::COLOR_BayerRG2GRAY = 88, cv::COLOR_BayerGR2GRAY = 89, cv::COLOR_BayerBG2BGR_VNG = 62, cv::COLOR_BayerGB2BGR_VNG = 63, cv::COLOR_BayerRG2BGR_VNG = 64, cv::COLOR_BayerGR2BGR_VNG = 65, cv::COLOR_BayerBG2RGB_VNG = COLOR_BayerRG2BGR_VNG, cv: :COLOR_BayerGB2RGB_VNG = COLOR_BayerGR2BGR_VNG, cv::COLOR_BayerRG2RGB_VNG = COLOR_BayerBG2BGR_VNG, cv::COLOR_BayerGR2RGB_VNG = COLOR_BayerGB2BGR_VNG, cv::COLOR_BayerBG2BGR_EA = 135, cv::COLOR_BayerGB2BGR_EA = 136, cv::COLOR_BayerRG2BGR_EA = 137, cv ::COLOR_BayerGR2BGR_EA = 138, cv:: COLOR_BayerBG2RGB_EA = COLOR_BayerRG2BGR_EA, cv::COLOR_BayerGB2RGB_EA = COLOR_BayerGR2BGR_EA, cv ::COLOR_BayerRG2RGB_EA = COLOR_BayerBG2BGR_EA, cv::COLOR_BayerGR2RGB_EA = COLOR_BayerGB2BGR_EA, cv::COLOR_BayerBG2BGRA = 139, cv::COLOR_BayerGB2BGRA = 140, cv ::COLOR_BayerRG2BGRA = 141, cv::COLOR _BayerGR2BGRA = 142, cv::COLOR_BayerBG2RGBA = COLOR_BayerRG2BGRA, cv: :COLOR_BayerGB2RGBA = COLOR_BayerGR2BGRA, cv::COLOR_BayerRG2RGBA = COLOR_BayerBG2BGRA, cv::COLOR_BayerGR2RGBA = COLOR_BayerGB2BGRA, cv::COLOR_COLORCVT_MAX = 143 |
For details, please refer to the OpenCV documentation: Color Space Conversions
③Instance operation:
1. Net suppress cloud gray robot:
>>> import cv2
>>> src=cv2.imread("F://src.jpg")
>>> dst1=cv2.cvtColor(src,cv2.COLOR_BGR2GRAY)
>>> cv2.imwrite("F://1.jpg",dst1)
True
2. The robot whose san value collapses:
>>> dst2=cv2.cvtColor(src,cv2.COLOR_BGR2HSV)
>>> cv2.imwrite("F://2.jpg",dst2)
True
3. A robot with cool tones in the underworld (BGR space→RGB space causes the order of channels to change):
>>> dst3=cv2.cvtColor(src,cv2.COLOR_BGR2RGB)
>>> cv2.imwrite("F://3.jpg",dst3)
True 
Conclusion: In this article, we have learned the cvtColor function, how to convert the color space of the image, as well as its principles and usage methods. I hope that all students can learn and use it flexibly, and try it out by yourself. It is really interesting . (appreciated).
Well, the above is all the content. I hope you will pay more attention, like, and bookmark. This will be of great help to me.
I wish the country a healthy family, and see you next time! ! ! yo-yo~~
