access data of binary image and display coordinates of some points

edit

Hello everyone,

I want access image data of a binary image in order to determine the white point located in the up of the image(having minimal y), down(maximum y), right(maximum x), and in the left(having minimal X) of the image.

here is my code:

cvThreshold(gray, Treshold_img, 150, 255, CV_THRESH_BINARY); 
IplConvKernel *element = cvCreateStructuringElementEx(3, 3, 1,1, CV_SHAPE_RECT, NULL );
cvMorphologyEx(Treshold_img, Morphology_img, Temp_img, element, CV_MOP_CLOSE, 2);// remove noises

for (int i = 0; i < Morphology_img->height; i++){
    for (int j = 0; j < Morphology_img->width; j++)
{

        if ((Morphology_img->imageData[i* Morphology_img->widthStep + j] = 255) && (i<min_y))
    {
        min_y = i;
        min_y_x = j;

    }

        else if (Morphology_img->imageData[i* Morphology_img->widthStep + j] = 255 && j < min_x)
    {
        min_x = j;
        min_x_y = i;

    }
        else if (Morphology_img->imageData[i* Morphology_img->widthStep + j] = 255 && i > max_y)
    {
        max_y = i;
        max_y_x = j;

    }
        else if (Morphology_img->imageData[i* Morphology_img->widthStep + j] = 255 && j >max_x)
    {
        max_x = j;
        max_x_y = i;

    }

}
}

The problem is that when i run the code , my Morphology_img become a white image and the coordinate of my points are not correct. Any help? any Idea?
Thanks