Vingetting an image using loop

This is my work below I keep getting a black image for my vinColor. Any suggestions?

Color = imread('sunflower.jpg');
Center = size(Color)/2+.5;
[l,h,~] = size(Color);
for x=1:l
    for y=1:h
        d = sqrt((x-Center(1))^2+(y-Center(2))^2);
    end
    D = 246.9261
    r = d./D
end

imshow(Color)
VinColor = Color .* (1-r.^2);
figure(2)
imshow(VinColor)

[Geoff Hayes]

Yogesh - I don't understand the code within your loops. For example,

for y=1:h
    d = sqrt((x-Center(1))^2+(y-Center(2))^2);
end

you replace the d calculated on subsequent iterations with the d calculated on the current iteration. Is this an oversight? Don't you want to somehow include the previous iteration calculations? Similarly, in

D = 246.9261
r = d./D

you overwrite the r that has been caculated on the previous iteration of the outer for loop. Is this intentional? How should the "historical" values be used in your calculations?

[Yogesh Bhambhwani]

I did that since I wanted to find the max d and divide it by all of the d values and to do that I had to include it in the loop others wise it would only divide by the max d and not the other values.

[KSSV]

If you want to get the max..you have to store the d values in to an array.

for y=1:h
    d(y) = sqrt((x-Center(1))^2+(y-Center(2))^2);
end
D = max(d) ;

[Yogesh Bhambhwani]

okay but I need to take that max and divide it by all of the values d how would I do that?

Answer 1

[Subhadeep Koley]

Hope this works.

colorImg = im2double(imread('kobi.png'));
center = size(colorImg)/2+.5;
[l,h,~] = size(colorImg);
d = zeros(l, h);
for x=1:l
    for y=1:h
        d(x, y) = sqrt((x-center(1))^2+(y-center(2))^2);
    end
end
D = max(d);
r = d./D;
vinColor = colorImg .* (1-r.^2);

figure
montage({colorImg, vinColor})

[Yogesh Bhambhwani]

It gives me the error

Undefined function 'montage' for input arguments of type 'cell'.

[Subhadeep Koley]

That's just for visualization. You can use imshow too, like below.

colorImg = im2double(imread('kobi.png'));
center = size(colorImg)/2+.5;
[l,h,~] = size(colorImg);
d = zeros(l, h);
for x=1:l
    for y=1:h
        d(x, y) = sqrt((x-center(1))^2+(y-center(2))^2);
    end
end
D = max(d);
r = d./D;
vinColor = colorImg .* (1-r.^2);

figure
imshow(colorImg)

figure
imshow(vinColor)