coding for implementing gaussian filter in iris recognition system

Hi.. help me with the code mentioned above.

Answer 1

[David Young]

Provided you have the Image Processing Toolbox, code for Gaussian filtering of an image looks like this:

sigma = 2; % set sigma to the value you need
sz = 2*ceil(2.6 * sigma) + 1; % See note below
mask = fspecial('gauss', sz, sigma);

newImage = conv2(Image, mask, 'same');

The choice of the size of the mask (or kernel) array is a trade-off between truncation errors and computation time. The formula above is a reasonable compromise which also makes the mask size odd, so that the mask has a definite centre.

The 'same' option in conv2 makes newImage the same size as Image, which is convenient, but it assumes that Image is surrounded by zeros, so pixels near the boundary of newImage will be pulled towards zero.

If you are doing a lot of this, you may find that convolve2 (in the file exchange) saves time, as it is faster than conv2 for masks above a certain size. convolve2 also offers a 'reflect' option which produces output which often displays better than conv2(..., 'same') by making a symmetry assumption at the boundaries. filter2 should also be fast, but does not have the 'reflect' boundary option.

[Tharini]

Need code for iris normalisation

[David Young]

I've given a reply to the question you asked. Normalisation is a different matter, so perhaps you should ask a new question, but you will need to explain what you mean by normalisation.

Also, if this answer was useful, you could accept it, or if it was not, you should explain what is wrong.

[Tharini]

Iris normalisation means to extract iris patterns from the eye and to scale it to a predefined size. I need code for the above mentioned problem.

Answer 2

[haris zafar]

hey david!!!

     why you have used ceil function??? 

     sz = 2*ceil(2.6 * sigma) + 1;
     explain this statement

regards

[David Young]

The size has to be a positive integer. It's convenient if it's an odd integer. I use ceil because rounding up makes the truncation error smaller rather than bigger - but it's not important.

Answer 3

[Suba thangaraj]

can you give me enhancement code for mammogram

Answer 4

[Kavita NARGULLA]

I want Iris recognition code in matlab