Question

I need to develop a method to find the distance of a red line and the bottom of the image.
I already isolate the red line in hsv using some examples…
I know how to do this using MatLab but now i have to use the opencv :s
Someone can tell me how to do this?

Answer 1

You can access each pixel value of the image in following way.

IplImage* img=cvLoadImage("your_image.jpg");
int pixelVal;
for(int x=0;x<img->height;x++){
for(int y=0;y<img->width;y++){
    pixelVal=((uchar*)(img->imageData + img->widthStep*x))[y];
}
}

in here,

img->imageData returns a pointer to starting memory location of the image

img->widthStep is the number of bytes in a image row

we access the each pixel value and cast using unsigned char pointer to get int value.