Looking to identify a football from an image

I currently have a still image of a football about to be kicked. I would like to identify the ball and it's center.

Answer 1

[Kevin Holly]

RGB = imread('YourImage.png');

% Convert RGB image to lab space
I = rgb2lab(RGB);

% Apply thresholds
BW = (I(:,:,1) >= 14.5 ) & (I(:,:,1) <= 89.77) & ...
    (I(:,:,2) >= 0.12) & (I(:,:,2) <= 12.5) & ...
    (I(:,:,3) >= 3.8) & (I(:,:,3) <= 33.0);

% Open mask
se = strel('disk', 13,0);
BW = imopen(BW, se);

% Filter out smaller objects
BW=bwareafilt(BW,[50000 Inf]);

% Find Centroid and Area of object
rp = regionprops(BW,"Centroid","Area")

rp = struct with fields:
        Area: 58864
    Centroid: [644.7752 215.7900]

% Display masked image for verfication purposes
maskedRGBImage = RGB;
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

imshow(maskedRGBImage)

% Add marker on centroid
hold on
scatter(rp.Centroid(1),rp.Centroid(2),'b','filled')

[Michael Sposato]

I also need this to work for other images as well. What is there to change to do this? I attached another sample image as well.

Also how is the centroid calculated? Is it by the extremes or by matlab calculating the area of the ellipse?