I have a Mat object of type CV_32FC1 of size 300x300 ....
I tried :
B=Mat::ones(rows,cols,CV_32FC1)*100;
...process B...
Mat res_B=Mat::zeros(480,640,CV_32FC1);
resize(B, res_B, Size(640,480), 0, 0, INTER_CUBIC);
How to resize it to size 640x480 ?? When I used the resize() function in OpenCV it doesnt seem to work...Any suggestions??
The following code works:
cv::Mat B = cv::Mat::ones(300,300,CV_32FC1);
for (int i = 0; i < 100; i++)
{
B.at<int>(50, i) = 0;
B.at<int>(51, i) = 0;
}
cv::Mat res_B;
resize(B, res_B, Size(640, 480));
namedWindow( "Display Image", CV_WINDOW_AUTOSIZE );
imshow( "Display Image", B );
imshow( "Display Resized Image", res_B );
waitKey(0);
I hope it will help.
Maybe there is something I don't get, but isn't it normal if you put data in a matrix, then expand it to not have the same result everywhere because of the interpolation ?
Even if the matrix is homogeneous, i noticed that OpenCV do some weird things with floating point values (maybe some double => float truncation) that I couldn't explain by the fact that the set of floating point values is not continuous.
So the essence of interpolation is to "create" data that could be correct regarding the neighbourhood.
Or am I just really far of the problem here ?
Yes..It resizes properly.... if I give the interpolation option as INTER_NEAREST or INTER_LINEAR... if i use INTER_CUBIC , there are several negative values in the resized matrix whereas I had all positive values in the original matrix..... Do you know why INTER_CUBIC generates negative float values in resized matrix.... I still used it for an Image(uchar) and got the resized image pretty well
Asked: 2013-04-25 07:23:09 -0600
Seen: 8,728 times
Last updated: Apr 26 '13
what exactly does not work ?
I could reproduce your code and it works. I printed the matrix using the following code:
cv::namedWindow("Display Image", CV_WINDOW_AUTOSIZE); imshow("Display Image", res_B); waitKey(0);@berak All values in res_B are 100.... But after processing B contains several floating point nos... In the resized Mat res_B it is not !!
@Nyenna Did you use Float Mat ??? I think,imshow function supports only CV_8UC1 ..
I used the very same code that you posted (without the processing part, of course). Are you sure you process B correctly? Can you verify that you do by showing the image just before the
resize()line?No...aftr processing there will be floating values in Mat.... You manually assign certain pixels with float values such as 21.11,19.33,88.43 and then resize ...and display...do you get same result???