在opencv中使用Mat :: at（i，j）获取2-D Mat对象

问题描述

我使用的是Ubuntu 12.04和opencv 2

I am using Ubuntu 12.04 and opencv 2

我写了以下代码：

    IplImage* img =0;
    img = cvLoadImage("nature.jpg");
    if(img != 0)
    {
        Mat Img_mat(img);
        std::vector<Mat> RGB;
        split(Img_mat, RGB);

        int data = (RGB[0]).at<int>(i,j)); /*Where i, j are inside the bounds of the matrix size .. i have checked this*/
}

问题是在数据变量中我得到负值和非常大的值。我想我在某个地方犯了一些错误。你能指出来吗？
我一直在阅读文档（我没有完成它..它是相当大。）但是从我已经阅读，这应该工作。但它不是。这是怎么回事？

The problem is I am getting negative values and very large values in teh data variable. I think I have made some mistake somewhere. Can you please point it out.I have been reading the documentation (I have not finished it fully .. it is quite large. ) But from what I have read, this should work. But it isnt. What is going wrong here ?

推荐答案

Img_mat 。每个通道由数据类型中的像素值 uchar 组成。
因此 split（Img_mat，BGR） Img_mat 分为3个平面的蓝色，绿色和红色，它们被共同存储在向量 BGR 中。因此 BGR [0] 是 uchar 数据类型像素的第一个（蓝色）

Img_mat is a 3 channeled image. Each channel consists of pixel values uchar in data type.So with split(Img_mat, BGR) the Img_mat is split into 3 planes of blue, green and red which are collectively stored in a vector BGR. So BGR[0] is the first (blue) plane with uchar data type pixels...hence it will be

int dataB = (int)BGR[0].at<uchar>(i,j);
int dataG = (int)BGR[1].at<uchar>(i,j);

等等...

strong> @bsdnoobz 我想你想写

@bsdnoobz I think you wanted to write

Vec3b data = Img_mat.at<Vec3b>(i,j);
data[0] = // blue pixel
data[1] = // green pixel

等等...

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