【OpenCV3.1 第5篇】 相关操作: mean、clone、zeros、circle、cvtColor、meanStdDev、split

mean();

计算 各通道选中区域（默认全图）的平均值。

//! computes mean value of selected array elements
CV_EXPORTS_W Scalar mean(InputArray src, InputArray mask=noArray());

示例：

cv::Scalar meanVal = mean(srcImage);
double avg;
if (srcImage.channels() == 1)
{
avg = meanVal[0];
}
if (srcImage.channels() == 3)
{
avg = (meanVal[0] + meanVal[1] + meanVal[2]) / 3;
}

clone

复制图像

示例：

Mat image = srcImg.clone();

zeros

创建一张黑（全0）图

示例：

Mat temp1ch = Mat::zeros(srcImg.size(), CV_8UC1);
Mat temp3ch = Mat::zeros(srcImg.size(), CV_8UC3);

circle

//! draws the circle outline or a solid circle in the image
CV_EXPORTS_W void circle(CV_IN_OUT Mat& img, Point center, int radius,
const Scalar& color, int thickness=1,
int lineType=8, int shift=0);

示例：

circle(temp1ch, Point(temp1ch.cols / 2, temp1ch.rows / 2), radius, Scalar(255), CV_FILLED);
circle(temp3ch, Point(temp3ch.cols / 2, temp3ch.rows / 2), radius, Scalar(255, 255, 255), CV_FILLED);

cvtColor

颜色空间转换

//! converts image from one color space to another
CV_EXPORTS_W void cvtColor( InputArray src, OutputArray dst, int code, int dstCn=0 );

code 为转换类型，最常用的：CV_BGR2GRAY

示例：

Mat grayImg;
cvtColor(image, grayImg, CV_BGR2GRAY);

下面为所有转换类型

enum
{
CV_BGR2BGRA    =0,
CV_RGB2RGBA    =CV_BGR2BGRA,

CV_BGRA2BGR    =1,
CV_RGBA2RGB    =CV_BGRA2BGR,

CV_BGR2RGBA    =2,
CV_RGB2BGRA    =CV_BGR2RGBA,

CV_RGBA2BGR    =3,
CV_BGRA2RGB    =CV_RGBA2BGR,

CV_BGR2RGB     =4,
CV_RGB2BGR     =CV_BGR2RGB,

CV_BGRA2RGBA   =5,
CV_RGBA2BGRA   =CV_BGRA2RGBA,

CV_BGR2GRAY    =6,
CV_RGB2GRAY    =7,
CV_GRAY2BGR    =8,
CV_GRAY2RGB    =CV_GRAY2BGR,
CV_GRAY2BGRA   =9,
CV_GRAY2RGBA   =CV_GRAY2BGRA,
CV_BGRA2GRAY   =10,
CV_RGBA2GRAY   =11,

CV_BGR2BGR565  =12,
CV_RGB2BGR565  =13,
CV_BGR5652BGR  =14,
CV_BGR5652RGB  =15,
CV_BGRA2BGR565 =16,
CV_RGBA2BGR565 =17,
CV_BGR5652BGRA =18,
CV_BGR5652RGBA =19,

CV_GRAY2BGR565 =20,
CV_BGR5652GRAY =21,

CV_BGR2BGR555  =22,
CV_RGB2BGR555  =23,
CV_BGR5552BGR  =24,
CV_BGR5552RGB  =25,
CV_BGRA2BGR555 =26,
CV_RGBA2BGR555 =27,
CV_BGR5552BGRA =28,
CV_BGR5552RGBA =29,

CV_GRAY2BGR555 =30,
CV_BGR5552GRAY =31,

CV_BGR2XYZ     =32,
CV_RGB2XYZ     =33,
CV_XYZ2BGR     =34,
CV_XYZ2RGB     =35,

CV_BGR2YCrCb   =36,
CV_RGB2YCrCb   =37,
CV_YCrCb2BGR   =38,
CV_YCrCb2RGB   =39,

CV_BGR2HSV     =40,
CV_RGB2HSV     =41,

CV_BGR2Lab     =44,
CV_RGB2Lab     =45,

CV_BayerBG2BGR =46,
CV_BayerGB2BGR =47,
CV_BayerRG2BGR =48,
CV_BayerGR2BGR =49,

CV_BayerBG2RGB =CV_BayerRG2BGR,
CV_BayerGB2RGB =CV_BayerGR2BGR,
CV_BayerRG2RGB =CV_BayerBG2BGR,
CV_BayerGR2RGB =CV_BayerGB2BGR,

CV_BGR2Luv     =50,
CV_RGB2Luv     =51,
CV_BGR2HLS     =52,
CV_RGB2HLS     =53,

CV_HSV2BGR     =54,
CV_HSV2RGB     =55,

CV_Lab2BGR     =56,
CV_Lab2RGB     =57,
CV_Luv2BGR     =58,
CV_Luv2RGB     =59,
CV_HLS2BGR     =60,
CV_HLS2RGB     =61,

CV_BayerBG2BGR_VNG =62,
CV_BayerGB2BGR_VNG =63,
CV_BayerRG2BGR_VNG =64,
CV_BayerGR2BGR_VNG =65,

CV_BayerBG2RGB_VNG =CV_BayerRG2BGR_VNG,
CV_BayerGB2RGB_VNG =CV_BayerGR2BGR_VNG,
CV_BayerRG2RGB_VNG =CV_BayerBG2BGR_VNG,
CV_BayerGR2RGB_VNG =CV_BayerGB2BGR_VNG,

CV_BGR2HSV_FULL = 66,
CV_RGB2HSV_FULL = 67,
CV_BGR2HLS_FULL = 68,
CV_RGB2HLS_FULL = 69,

CV_HSV2BGR_FULL = 70,
CV_HSV2RGB_FULL = 71,
CV_HLS2BGR_FULL = 72,
CV_HLS2RGB_FULL = 73,

CV_LBGR2Lab     = 74,
CV_LRGB2Lab     = 75,
CV_LBGR2Luv     = 76,
CV_LRGB2Luv     = 77,

CV_Lab2LBGR     = 78,
CV_Lab2LRGB     = 79,
CV_Luv2LBGR     = 80,
CV_Luv2LRGB     = 81,

CV_BGR2YUV      = 82,
CV_RGB2YUV      = 83,
CV_YUV2BGR      = 84,
CV_YUV2RGB      = 85,

CV_BayerBG2GRAY = 86,
CV_BayerGB2GRAY = 87,
CV_BayerRG2GRAY = 88,
CV_BayerGR2GRAY = 89,

//YUV 4:2:0 formats family
CV_YUV2RGB_NV12 = 90,
CV_YUV2BGR_NV12 = 91,
CV_YUV2RGB_NV21 = 92,
CV_YUV2BGR_NV21 = 93,
CV_YUV420sp2RGB = CV_YUV2RGB_NV21,
CV_YUV420sp2BGR = CV_YUV2BGR_NV21,

CV_YUV2RGBA_NV12 = 94,
CV_YUV2BGRA_NV12 = 95,
CV_YUV2RGBA_NV21 = 96,
CV_YUV2BGRA_NV21 = 97,
CV_YUV420sp2RGBA = CV_YUV2RGBA_NV21,
CV_YUV420sp2BGRA = CV_YUV2BGRA_NV21,

CV_YUV2RGB_YV12 = 98,
CV_YUV2BGR_YV12 = 99,
CV_YUV2RGB_IYUV = 100,
CV_YUV2BGR_IYUV = 101,
CV_YUV2RGB_I420 = CV_YUV2RGB_IYUV,
CV_YUV2BGR_I420 = CV_YUV2BGR_IYUV,
CV_YUV420p2RGB = CV_YUV2RGB_YV12,
CV_YUV420p2BGR = CV_YUV2BGR_YV12,

CV_YUV2RGBA_YV12 = 102,
CV_YUV2BGRA_YV12 = 103,
CV_YUV2RGBA_IYUV = 104,
CV_YUV2BGRA_IYUV = 105,
CV_YUV2RGBA_I420 = CV_YUV2RGBA_IYUV,
CV_YUV2BGRA_I420 = CV_YUV2BGRA_IYUV,
CV_YUV420p2RGBA = CV_YUV2RGBA_YV12,
CV_YUV420p2BGRA = CV_YUV2BGRA_YV12,

CV_YUV2GRAY_420 = 106,
CV_YUV2GRAY_NV21 = CV_YUV2GRAY_420,
CV_YUV2GRAY_NV12 = CV_YUV2GRAY_420,
CV_YUV2GRAY_YV12 = CV_YUV2GRAY_420,
CV_YUV2GRAY_IYUV = CV_YUV2GRAY_420,
CV_YUV2GRAY_I420 = CV_YUV2GRAY_420,
CV_YUV420sp2GRAY = CV_YUV2GRAY_420,
CV_YUV420p2GRAY = CV_YUV2GRAY_420,

//YUV 4:2:2 formats family
CV_YUV2RGB_UYVY = 107,
CV_YUV2BGR_UYVY = 108,
//CV_YUV2RGB_VYUY = 109,
//CV_YUV2BGR_VYUY = 110,
CV_YUV2RGB_Y422 = CV_YUV2RGB_UYVY,
CV_YUV2BGR_Y422 = CV_YUV2BGR_UYVY,
CV_YUV2RGB_UYNV = CV_YUV2RGB_UYVY,
CV_YUV2BGR_UYNV = CV_YUV2BGR_UYVY,

CV_YUV2RGBA_UYVY = 111,
CV_YUV2BGRA_UYVY = 112,
//CV_YUV2RGBA_VYUY = 113,
//CV_YUV2BGRA_VYUY = 114,
CV_YUV2RGBA_Y422 = CV_YUV2RGBA_UYVY,
CV_YUV2BGRA_Y422 = CV_YUV2BGRA_UYVY,
CV_YUV2RGBA_UYNV = CV_YUV2RGBA_UYVY,
CV_YUV2BGRA_UYNV = CV_YUV2BGRA_UYVY,

CV_YUV2RGB_YUY2 = 115,
CV_YUV2BGR_YUY2 = 116,
CV_YUV2RGB_YVYU = 117,
CV_YUV2BGR_YVYU = 118,
CV_YUV2RGB_YUYV = CV_YUV2RGB_YUY2,
CV_YUV2BGR_YUYV = CV_YUV2BGR_YUY2,
CV_YUV2RGB_YUNV = CV_YUV2RGB_YUY2,
CV_YUV2BGR_YUNV = CV_YUV2BGR_YUY2,

CV_YUV2RGBA_YUY2 = 119,
CV_YUV2BGRA_YUY2 = 120,
CV_YUV2RGBA_YVYU = 121,
CV_YUV2BGRA_YVYU = 122,
CV_YUV2RGBA_YUYV = CV_YUV2RGBA_YUY2,
CV_YUV2BGRA_YUYV = CV_YUV2BGRA_YUY2,
CV_YUV2RGBA_YUNV = CV_YUV2RGBA_YUY2,
CV_YUV2BGRA_YUNV = CV_YUV2BGRA_YUY2,

CV_YUV2GRAY_UYVY = 123,
CV_YUV2GRAY_YUY2 = 124,
//CV_YUV2GRAY_VYUY = CV_YUV2GRAY_UYVY,
CV_YUV2GRAY_Y422 = CV_YUV2GRAY_UYVY,
CV_YUV2GRAY_UYNV = CV_YUV2GRAY_UYVY,
CV_YUV2GRAY_YVYU = CV_YUV2GRAY_YUY2,
CV_YUV2GRAY_YUYV = CV_YUV2GRAY_YUY2,
CV_YUV2GRAY_YUNV = CV_YUV2GRAY_YUY2,

// alpha premultiplication
CV_RGBA2mRGBA = 125,
CV_mRGBA2RGBA = 126,

CV_RGB2YUV_I420 = 127,
CV_BGR2YUV_I420 = 128,
CV_RGB2YUV_IYUV = CV_RGB2YUV_I420,
CV_BGR2YUV_IYUV = CV_BGR2YUV_I420,

CV_RGBA2YUV_I420 = 129,
CV_BGRA2YUV_I420 = 130,
CV_RGBA2YUV_IYUV = CV_RGBA2YUV_I420,
CV_BGRA2YUV_IYUV = CV_BGRA2YUV_I420,
CV_RGB2YUV_YV12  = 131,
CV_BGR2YUV_YV12  = 132,
CV_RGBA2YUV_YV12 = 133,
CV_BGRA2YUV_YV12 = 134,

CV_COLORCVT_MAX  = 135
};

所有转换类型

meanStdDev

求各通道平均值，平均标准差

//! computes mean value and standard deviation of all or selected array elements
CV_EXPORTS_W void meanStdDev(InputArray src, OutputArray mean, OutputArray stddev,
InputArray mask=noArray());

示例：

meanStdDev(image, meanVal, stddevVal, temp1ch);

关于mask参数，参考文档：探讨opencv函数中的mask的作用

split

将图像各通道分离开

示例：

meanStdDev(image, meanVal, stddevVal, temp1ch);
vector<Mat>bgrImgs;
split(image, bgrImgs);
Mat b = (bgrImgs[0] - meanVal[0]) > stddevVal[0];
Mat g = (bgrImgs[1] - meanVal[1]) > stddevVal[1];
Mat r = (bgrImgs[2] - meanVal[2]) > stddevVal[2];
Mat bgrBin = b | g | r;

这段代码对图像进行了2值化