How to remove 'wood grain' (noise) background from image?

Question

I have been stuck on attempting to remove the background from a borehole log image for a week or so (new to image processing). I want to eventually develop a code which can automatically detect the horizontal sinusoidal features in the image (attached). I think for this I can use a Hough transform. However, all of the algorithms I have used (Hough transform, edge detections, thresholding) do not work because of the background of the image which has this 'wood grain' appearance. I also tried recreating a mask through finding the image gradient, but because the color values of the features I want (horizontal sinusiodal shapes) are so similar to the background I want to remove I am having a difficult time. The ultimate goal is to take two images taken at different times (before and after a scientific experiment) and to subtract them to see where the sinusoidal patterns differ. If I can get rid of this background that should be easier. I so far have worked the image to better quality through taking the FFT and applying a high-pass filter. This at least homogenizes the image and leaves me with the attached result. However, I am not having much luck to remove this vertical 'wood grain'. Does anyone have a thought about how it could be done? This is driving me a little crazy. Thank you so much!