OpenCV 从 Mat 图像中获取像素通道值

问题描述：

也许我看起来不够努力，但似乎一切都希望我使用数组.因此，如果 foo 类似于 Mat foo = imread("bar.png")，我如何获得 foo 特定像素的通道值?

Maybe I'm not looking hard enough, but everything seems to want me to use an array. Thus, how do I get the channel value for a particular pixel for foo if foo is something like Mat foo = imread("bar.png")?

答

假设类型是 CV_8UC3 你会这样做:

Assuming the type is CV_8UC3 you would do this:

for(int i = 0; i < foo.rows; i++)
{
    for(int j = 0; j < foo.cols; j++)
    {
        Vec3b bgrPixel = foo.at<Vec3b>(i, j);

        // do something with BGR values...
    }
}

这里是 Vec3b 的文档.希望有帮助！另外，不要忘记 OpenCV 在内部将内容存储为 BGR 而不是 RGB.

Here is the documentation for Vec3b. Hope that helps! Also, don't forget OpenCV stores things internally as BGR not RGB.

出于性能原因，您可能希望使用对数据缓冲区的直接访问来处理像素值:

EDIT :
For performance reasons, you may want to use direct access to the data buffer in order to process the pixel values:

以下是您可以采取的方法:

Here is how you might go about this:

uint8_t* pixelPtr = (uint8_t*)foo.data;
int cn = foo.channels();
Scalar_<uint8_t> bgrPixel;

for(int i = 0; i < foo.rows; i++)
{
    for(int j = 0; j < foo.cols; j++)
    {
        bgrPixel.val[0] = pixelPtr[i*foo.cols*cn + j*cn + 0]; // B
        bgrPixel.val[1] = pixelPtr[i*foo.cols*cn + j*cn + 1]; // G
        bgrPixel.val[2] = pixelPtr[i*foo.cols*cn + j*cn + 2]; // R

        // do something with BGR values...
    }
}

或者:

int cn = foo.channels();
Scalar_<uint8_t> bgrPixel;

for(int i = 0; i < foo.rows; i++)
{
    uint8_t* rowPtr = foo.row(i);
    for(int j = 0; j < foo.cols; j++)
    {
        bgrPixel.val[0] = rowPtr[j*cn + 0]; // B
        bgrPixel.val[1] = rowPtr[j*cn + 1]; // G
        bgrPixel.val[2] = rowPtr[j*cn + 2]; // R

        // do something with BGR values...
    }
}

OpenCV 从 Mat 图像中获取像素通道值

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