when reading pixel of image,using this sentence: (unsigned int)img_pyr2.at<uchar>(y, x) I don't know that why use the data type,uchar. when i changed uchar to int,it will be error;
i just learn opencv,pleace help me to understand. Thank you.
For each image type you have the according data type: uchar for CV_8U, Vec3b for CV_8UC3, ushort for CV_16U, int for CV_32S, float for CV_32F etc.
Always use the according data type:
Mat image(100,100,CV_8UC1);
uchar pixel=image.at<uchar>(10,10);
(you don't need a second type cast: pixel=(uchar)img.at<uchar>(10,10);)
The pixel access in OpenCV is quite well explained in the docs.
It's also good to learn the pointer (line) access.
you also have to learn C++, see e.g. C++ Templates
<uchar> is a template parameter and means that img_pyr2 must be of type uchar
if you would like to convert an uchar image to int you should use img_pyr2.convertTo(img_pyr_int, CV_32S);. Afterwards you can access the pixels via img_py_int.at<int>(y, x)
Asked: 2018-01-16 03:09:20 -0600
Seen: 977 times
Last updated: Jan 16 '18
