erosion / dilation help for newbies

I am a master student which is not about matlab lesson but i have to take that course. My advisor force me to take that class. Its my homework. I try to solve that second homework but i coulndt make it.

the assament is like that

PART 1 (Do not use imerode, imclose, bwmorph etc functions to answer this part) 1. Write a MATLAB/(or octave etc) function which performs erosion and dilation for an input image with a square structuring element of size N. Although, matlab image processing toolbox has imerode, imdilate methods. I want you to implement method yourself with for loops. Normally, you will need four for-loops to implement this, however by using matlabs vectoral indexing you can do it with two loops. Ex: Let A be a 640*480 binary image. B= A(1:100,200:300); assigns a 100x100 window to B or B = A(x-5:x+5, 1:100); puts a 10x100 window which are 5 rows below and above x and columns 1 to 100. 2. Write MATLAB function which performs opening and closing using allready defined erosion and closing operations.

PART 2 (Here you can use existing matlab functions, imopen,imclose,bwlabel) 3. Suppose that you have customer which needs an automatic coin counter for dolmush drivers who throw some number of coins on a black surface and need them counted. Assume that you have a good binarization process which produces good binary images like ‘coinsbin.png’ . Write a matlab method which calculates the total value of the coins, where the big coins are 0.5TL and smaller coins are 0.25TL. To answer this question you must use morphological operations and labelling. Demonstrate its use by calculating total value in coinsbin.png and coinsbin2.png images

[Walter Roberson]

merged into duplicate http://www.mathworks.co.uk/matlabcentral/answers/65869-erosion-dilation-help-for-newbies