Best way of segmenting veins from arm? I have done fews researches and found out approach such as


multiscale and 
region growing,


that could be used of extracting forearm veins.

However, I tried to use frangi filter and Figure 1 is the segmentation result using the best parameter set I could found;


Figure 1

Could anyone suggest what approaches as well the technique to adopt while considering this problem?

I give extra image for further analysis:
So one good step to enhance the vein-like structures is coherence enhancing diffusion:


  Weickert, Joachim. "Coherence-enhancing diffusion filtering." International Journal of Computer Vision 31.2-3 (1999): 111-127.


So I first apply this algorithm to your image, aggressively. The next step is to identify the curvilinear structures, which would in this case extract the veins. I already explained how to do this robustly in a previous post. So please check this.

The result is the following:


One could apply all the desired noise cleaning to this image. Note that the edges appear very weak, so it is better to tune the parameters, probably even more than I did.