I want MATLAB to identify the overlapping area.

I have a hexagonal grid. The following is its code:

 l=10;
    k=12;
    C=rand(l,k);
    xhex=[0 1 2 2 1 0]; 
    yhex=[2 3 2 1 0 1]; 

    for i=1:k
        j=i-1;
        for q=1:l
            m=q-1;
            patch((xhex+mod(q,2))+2*j,yhex+2*m,C(q,i)) 
            hold on
        end
    end
    axis equal

I want to place this grid on an image. Code for image is:

P=imread('design2image_pa.png');
imshow(P)
grayImage = imread('design2image_pa.png');
imshow(grayImage, [], 'XData', [0, 50], 'YData', [0, 77]);
axis('on', 'image');
   

The output I want is only the hexagons that overlap with the circle to appear. Can someone kindly help me out with this. Many thanks.

Answer 1

[Voss]

I don't have the image file, but you mention a circle, so I've specified a circle and modified the hexagon grid code to create only those hexagons which have at least one vertex strictly inside the circle. Maybe this modified code can be a useful reference for you.

R_circle = 6;
C_circle = [15 11.5];

l=10;
k=12;
C=rand(l,k);
xhex=[0 1 2 2 1 0]; 
yhex=[2 3 2 1 0 1]; 
hold on
for i=1:k
    j=i-1;
    for q=1:l
        m=q-1;
        x = (xhex+mod(q,2))+2*j;
        y = yhex+2*m;
        if any((x-C_circle(1)).^2 + (y-C_circle(2)).^2 < R_circle^2)
            patch(x,y,C(q,i));
        end
    end
end
axis equal

th = linspace(0,2*pi,200);
line(C_circle(1)+R_circle*cos(th),C_circle(2)+R_circle*sin(th), ...
    'Color','k','LineWidth',2)

[Mariam Shahab]

Thank you for your help.

I have attached the image. Could you kindly guide me on what the code will be when using this image? Thanks in advance.

Answer 2

[Image Analyst]

If you have a color digital image, and a binary image of the circle, which you can get using poly2mask, then you can mask the image with the mask like this:

% Mask the image using bsxfun() function to multiply the mask by each channel individually.  Works for gray scale as well as RGB Color images.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));

Attach your 'design2image_pa.png' image if you want more help.

[Mariam Shahab]

I have attached the image.

[Image Analyst]

I'm confused about the coordinates. Your patches go from 4-18 and 0-20 yet your digital image is huge, way bigger than that. If you end up with a digital image of 18 pixels by 20 pixels, you won't have enough resolution to give good images of the colored regions. What is your overall goal? Is a digital image of say the size of your attached circle image going to be okay? If so, can you make up a colored patch image of the same size?

[Mariam Shahab]

Well, the goal is that the program is able to give me only those colored regions where it identified an overlap with the circle (or any figure). The figure size has to be smaller than the colored region.

[Image Analyst]

That's not the higher goal. What's the use case? Is it your homework assignment? Or are you making some kind of plate or grate that will cover a hole or pipe in a nuclear power plant or some kind of machinery?