c++ - Rotating a 2D pixel array by 90 degrees

Question

I have an array of pixel data for an image. The image I am getting is already rotated to 270 degrees. So I am trying to rotate it again by 90 degrees to have the correct image. I've tried a transpose algorithm, by changing data[x][y] to data[y][x], but I don't think that's the correct way. Can anyone guide me what can I do to have it rotated?

Answer 1

You have old_data[rows][cols] and new_data[cols][rows], then:

for(int i=0; i<cols; i++) {
    for(int j=0; j<rows; j++) {
        new_data[i][j] = old_data[rows-1-j][i];
    }
}

This should rotate old_data by 90 degrees CW.