If this is your "final research", than do your research. Vein based identification is an emerging approach in biometric identification, and it is not as simple as you drafted: it's not just a matter of image comparison. First of all, there are several major targets, like palm, finger and even full-body based identification. On one hand the vein system is not planar (it is a 3D object), it is not constant and not static; on the other hand you have to consider the technique and the device you are using to capture the images.
But as the fingerprint recognition is based on a coding of the captured pattern (more precisely of it's specific and characteristic aspects), and the comparison is not a comparison of images but of these codes - the vein pattern recognition has just the same basic idea. But as fingerprint recognition is an old and well documented science, vein pattern recognition is new.
This could be a simple approach:
Let's suppose you have an image (A) .
Do a histogram correction to enhance vein visibility B=Hc(A)
Find the "color range" of the veins and suppress all other C=Cr(B)
Make a morphological skeleton detection for the veins on the enhanced image D=S(B)
Using A and B make a vectorized version of the skeleton E=V(B,D), with reduced point set
Now you have a bunch of lines.
That was the easiest part, since you need to figure out a coding technique. This is my level 0 suggestion:
Store every line with it's polar coordinate from the perimeter of the hand, and from the other lines around it. This can be the coded pattern.
Now, when you match the two patterns, you ca't use a discrete approach. Use some parallel approach to find the best matching candidates. Give a weight to the number of matched lines, the deviation of length of the matched lines, the deviation of the coordinates of the matched lines. So you can get a rank of the overall recognition. The higher the value, the better the recognition.
Of course, this can be refined considerably, so don't waste your time and look for publications in this topic. And hope you can get them from the university library...
] can be a great help for you