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Aim of this lab:

The aim of this laboratory session is to familiarize you with MATLAB's morphological operations erode and dilate.
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At the beginning, we were ask to perform the dilation and erosion operation on our own image. Before doing this, we first convert out image into grey scale and threshold it.
The following are the results of my images after applying the dilation and erosion operation.
Figure4 and Figure5 is the dilation and erosion of my grey scale image with a circular structuring element of size 4 respectively..

MATLAB Command:
g = rgb2gray(im);                    %convert image to grey scale
bw = g > 75;                         %thresh image, thresh = 75
object = circularstruct(4);          %set circular structuring element of size 4 
im_dilate = imdilate(bw,object);     %dilate my image  
im_erode = imerode(bw,object);       %erode my image
imshow(im_dilate);                   %display dilated image
imshow(im_erod);                     %display eroded image

                                       
Figure1: My grey scale image                   Figure2: Histogram of my image                Figure3: My image thresholded at the value of 75

           
Figure4: Dilation of my image                   Figure5: Erosion of my image

Then we applied the opening and closing operations on the image.
Closing operation is an operation of dilation followed by erosion. Whereas, the opening operation is an operation of erosion followed by dilation.
2 different options have been carried out to apply the opening and closing operations on the image. One is with a circular structuring element and the other one is a rectangular structuring element. Figure6 and Figure7 below are the opening and closing of my image.
To make things more interesting, we applied open-close (Figure8) and close-open(Figure9) operation as well.

Operations with a circular structuring element of size 4

MATLAB Command:
object = circularstruct(4);                  %set circular structuring element of size 4 
im_open = imopen(bw,object);                 %open
im_close = imclose(bw,object);               %close
im_openclose = imclose(im_open,object);      %open-close
im_closeopen = imopen(im_close,object);      %close-open 

       
Figure6: Open                                        Figure7: Close

       
Figure8: Open-close                              Figure9: Close-open

Operations with a rectangular structuring element with height = 2 and width = 4

MATLAB Command:
object = ones(2,4);        %set rectangular structuring element with height 2 and width 4

   
Figure10: Open                                      Figure11: Close

   
Figure12: Open-close                            Figure13: Close-open

The next task of this lab was to write a MATLAB function called locatelandmarks.m. This function will locate the 4 corners of a SURF form and returnt the coordinates of the 4 corners, topleft, topright, bottomleft and bottomright. This function will also detect if the form is upside down. Testing was done with a few SURF form with different sizes. surf01 and surf02 are forms which is slightly smaller than the other surf forms. Whereas surf11 is a form which is upside down. The locatelandmarks function was able to detect all the 4 corners of all these forms including those which size is halved (Figure26) and warning ("Form is Upside Down") appears if the form is upside down (Figure11).

   
Figure14: Surf01                                              Figure15: [tl tr bl br] = locatelandmarks(surf1);

   
Figure16: Surf02                                              Figure17: [tl tr bl br] = locatelandmarks(surf2);

   
Figure18: Surf05                                               Figure19: [tl tr bl br] = locatelandmarks(surf5);

   
Figure20: Surf06                                              Figure21: [tl tr bl br] = locatelandmarks(surf6);

   
Figure22: Surf10                                            Figure23: [tl tr bl br] = locatelandmarks(surf6);

   
Figure24: Surf11 (Upside down)                      Figure25: [tl tr bl br] = locatelandmarks(surf11);

       
Figure26: Surf01 (Half size)             Figure27: [tl tr bl br] = locatelandmarks(surf1resize);