What are the Advantages of sharpening image using laplacian filter?

I am working on face recognition. So, i will like to ask if pre processing of image using laplacian filter to sharpen the image can increase the recognition or classification rate? I will also like to know the different between normal image and sharpen image and what happens to the pixel values when an image is sharpen. And also what are the advantages of sharpening image and its drawbacks.