How to Enhance this finger print?
Two steps,


do a simple histogram equalization to make the brightness a little
bit more even.
Then use canny edge detector (as suggested by Marcus Muller).


matlab code:

I=imread('Your Image');
G1=rgb2gray(I);
G2=histeq(G1);
E2=edge(G2,'canny'); 
figure imshow(E2,[]);


Result (I hope it is what your are looking for):