Hi,
I have completed my master's in aerospace engineering, my master's project was to extract the high speed flow features from schlieren images. these images are very specific in aero field, they capture flow density gradients (known as shocks, shear layer) and are very noisy due to nature of schlieren optics. My whole work was to extract these flow features from these images, and I had to use many image processing techniques like low pass filtering (reducing noise), contrast adjustment, Fourier analysis based filtering to capture specific features and edge detection for the shocks.
I can help you enhance you images to visualize more details for your further analysis.