How does this technique work properly?

img1=imread(fn1);

H=slbp(img1);

[DGM]

I don't know that anyone will know without guessing. As far as I know, the function slbp() isn't part of base Matlab or any toolbox, and it's not part of any FEX submission. If you know what slbp() does, you'll have to describe it. In what context is it used? What is the intended result?

[ASMA MOHAMMAD]

I know that it is not in the toolbox, and it is a function that I have and I want to use it on a set of images to extract the features from the image of the fingerprint

[DGM]

My guess is that it's some sort of local binary pattern feature extraction tool. I have no idea, because it really has no proper documentation, and I'm not familiar with the subject. That should be enough to look up some information on the theory though.

I have no idea where this came from or if there was some sort of helpful information it came with. I don't know why you expected anyone to know what it was when you knew it wasn't anything we could identify. This isn't the first time you've asked unanswerable questions based on information to which you are the only one with access.

[ASMA MOHAMMAD]

slbp is a function that extracts features from an image. I want to know how to call this function

[DGM]

Yes, we've established that. I still don't know where this came from or if there is any usage information outside the file (maybe this is part of a toolbox that has other documentation files included). Given that the function seems to support more than one syntax, one could probably look at the input parsing section and try to guess which ones are which and what the expected ranges are.

I'm not inclined to chase that rabbit. Someone else can try. My recommendation is to find whoever wrote this and ask them why they published code with no usage documentation and such helpful error messages as error('Input arguments');