c++ image rotation 90 degree

Asked Mar 20 '20 at 17:05

Active Mar 20 '20 at 17:37

Viewed 319 times

I want to read the picture in grayscale and rotate it 90 degrees, but I am making a mistake somewhere. Is there anyone who can help?

cv::Mat image = imread(".../jpg", IMREAD_GRAYSCALE);
cv::resize(image, image,cv::Size(400,400));
cv::Mat imageson;

int rows = image.rows;
int cols = image.cols;


for (int i = 0; i < cols; i++)
{
    for (int j = 0; j < rows ; j++)
    {
        imageson.at<uchar>(i,j) = image.at<uchar>(rows-1-j,i);
    }
}

cv::imshow("image",imageson);
cv::waitKey(0);

// im beginner btw. output = (exit value:-1)

edited Mar 20 '20 at 17:37

asked Mar 20 '20 at 17:05

newbiec0der

_making a mistake_ What sort of mistake? Compilation error? Wrong image? Runtime error? [Edit] the question to include these details. – 1201ProgramAlarm Mar 20 '20 at 17:23
@pero_hero how to get -1 that row value is 400 – newbiec0der Mar 20 '20 at 17:32
sorry weak moment – pero_hero Mar 20 '20 at 17:33
1

Why dont you use [rotate](https://stackoverflow.com/questions/2259678/easiest-way-to-rotate-by-90-degrees-an-image-using-opencv) function? The reoson of crashing is that the limits are exceeding of the size. – Yunus Temurlenk Mar 20 '20 at 17:33
I want to do without using the rotate function. I want to learn well because I have just started. – newbiec0der Mar 20 '20 at 17:36
@YunusTemurlenk I realized there was a problem on limit, but I could not fix it. – newbiec0der Mar 20 '20 at 17:41
2

You don't specify size or type of imageson – stark Mar 20 '20 at 17:42
@stark I throw the pixels into imageson in the for loop. after all, the original picture is 400x400. Won't there be 400x400 in imagenson? – newbiec0der Mar 20 '20 at 17:47
1

Ahh yesss, just initialise the imageson like ```cv::Mat imageson(400, 400, CV_8UC1);``` – Yunus Temurlenk Mar 20 '20 at 17:49
@stark && Yunus Temurlenk THANK YOU SO MUCH!!!! – newbiec0der Mar 20 '20 at 17:50
1

`cv::rotate(image, image, cv::ROTATE_90_CLOCKWISE);`? – michelson Mar 20 '20 at 18:44

c++ image rotation 90 degree

0 Answers0