Activity 8: Morphological Operations

For this activity, we are to predict and simulate the effects of the morphological operations dilation and erosion on some polygons. We are to perform dilation and erosion on a binary image of a square (50×50) , a triangle (base = 50 , height= 30), a circle (radius 25), a hollow square (60×60, edges are 4 pixels thick), and a plus sign (8 pixels thick and 50 pixels long for each line).

I used a 4x4, 2x4, 4x2 and a cross, 5 pixels long, one pixel thick as structuring elements drawn using GIMP.

The following are my predictions:


To confirm the predictions I used the following code:

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Obj = imread("C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle.bmp");
Obj = im2bw(Obj,1);

se1 = imread("C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\4x4.bmp");
se2 = imread("C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\2x4.bmp");
se3 = imread("C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\4x2.bmp");
se4 = imread("C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\cross.bmp");

E1d = dilate(Obj,se1,[1,1]);
E2d = dilate(Obj,se2,[1,1]);
E3d = dilate(Obj,se3,[1,1]);
E4d = dilate(Obj,se4);

E1e = erode(Obj,se1,[1,1]);
E2e = erode(Obj,se2,[1,1]);
E3e = erode(Obj,se3,[1,1]);
E4e = erode(Obj,se4);
scf(0);imshow(E1d,[]);
//scf(1);imshow(E2,[]);
imwrite(E1d,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\4x4triangle_dilate.bmp");
imwrite(E2d,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\2x4triangle_dilate.bmp");
imwrite(E3d,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\4x2triangle_dilate.bmp");
imwrite(E4d,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\crosStriangle_dilate.bmp");

imwrite(E1e,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\4x4triangle_erode.bmp");
imwrite(E2e,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\2x4triangle_erode.bmp");
imwrite(E3e,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\4x2triangle_erode.bmp");
imwrite(E4e,"C:\Users\RAFAEL JACULBIA\Documents\subjects\186\activity8\triangle\crosStriangle_erode.bmp");
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The following shows the results obtained for a square object:



The following are the results for the triangle

The Following are the results for the circle
The following are the results for the hollow square


The following are the results for the plus sign.
In general most of my predictions are correct specially for the cross and the square, but for the triangle and hollow square I believe I did not predict the result exactly. For the circle I was only correct on the size but on the general shape I believe I was not correct, (e.g. flatten edges of the circle).

For this I will give myself a great of 8/10 since I was not able to predict all of the results perfectly and at first I really did not understand the effects on a hollow square.

Many Thanks to the following people who helped me a lot in this activity.
Eduardo David
Elizabeth Ann Prieto