void QuickDemo::pixel_visit_demo(cv::Mat &image) { int w = image.cols; int h = image.rows; int dim = image.channels(); for (int row = 0; row < h; row++) { for (int col = 0; col < w; col++) { if (dim == 1)//灰度图像 { int pv = image.at<uchar>(row,col);//像素是字节类型 image.at<uchar>(row, col) = 255 - pv; } if (dim == 3)//彩色图像 { Vec3b bgr = image.at<Vec3b>(row, col); image.at<Vec3b>(row, col)[0] = 255 - bgr[0]; image.at<Vec3b>(row, col)[1] = 255 - bgr[1]; image.at<Vec3b>(row, col)[2] = 255 - bgr[2]; } } } for (int row = 0; row < h; row++) { uchar* current_row = image.ptr<uchar>(row); for (int col = 0; col < w; col++) { if (dim == 1)//灰度图像 { int pv = *current_row; *current_row++ = 255 - *current_row; } if (dim == 3)//彩色图像 { *current_row++ = 255 - *current_row; *current_row++ = 255 - *current_row; *current_row++ = 255 - *current_row; } } } imshow("像素读写", image); }
一、数组下标
for (int row = 0; row < h; row++) { for (int col = 0; col < w; col++) { if (dim == 1)//灰度图像 { int pv = image.at<uchar>(row,col);//像素是字节类型 image.at<uchar>(row, col) = 255 - pv; } if (dim == 3)//彩色图像 { Vec3b bgr = image.at<Vec3b>(row, col); image.at<Vec3b>(row, col)[0] = 255 - bgr[0]; image.at<Vec3b>(row, col)[1] = 255 - bgr[1]; image.at<Vec3b>(row, col)[2] = 255 - bgr[2]; } } }
- 如果图像是灰度图像（通道数为1），则使用.at(row, col)来访问像素值，并将像素值取反后写回图像
- 如果图像是彩色图像（通道数为3），则使用.at(row, col)来访问像素值。将每个通道的像素值取反后写回图像
二、指针
for (int row = 0; row < h; row++) { uchar* current_row = image.ptr<uchar>(row); for (int col = 0; col < w; col++) { if (dim == 1)//灰度图像 { int pv = *current_row; *current_row++ = 255 - *current_row; } if (dim == 3)//彩色图像 { *current_row++ = 255 - *current_row; *current_row++ = 255 - *current_row; *current_row++ = 255 - *current_row; } } }
- 对于灰度图像，使用指针current_row指向当前行的数据指针，然后通过*current_row++的方式逐个访问像素值，并将像素值取反后写回图像
- 对于彩色图像，同样使用指针current_row指向当前行的数据指针，然后通过*current_row++的方式逐个访问每个通道的像素值，并将像素值取反后写回图像
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