Image Filtering, Image enhancement

Dear Matlab Experts,

I need your help in improving the image that I have plot using surfc function in Matlab. Basically I am using a sensor to scan over the sample xy plane.The sample has 3 holes underneath the coating. The probe is scanned using raster scanning, with step size of 1 mm in each x and y direction. Scanning summary: Number of scanning point in x-direction: 80. Number of scanning point in y-direction: 74. Total scanning points: 80x74 = 5920.

I have attached the image of the sample and the image that I have plot using surfc function using Matlab, seems like I am having background noise and the smaller defect hardly to be image out. I have tried with wiener filter, median filter, and other types of filter, but not much improved.

Hope anyone can suggest me something.

Thank you.