How can I remove horizontal line glitches from an image?

Question

I am working on art project where we are automatically taking pictures of a petri dish, which is illuminated by a small LCD screen. Oftentimes, there appears to be "glitches" in the image (see image with glitch), it always look the same, a short, narrow, dark line segment. I believe it is due to the scanline of the background screen. I have tried different methods for smoothing it out, such as taking a few images (like, 10 images, one every second) and applying an averaging or a median to generate a filtered image but it does not seem to work. I also have some previous sets of images which I would like to fix. Is there some kind of automated way to do this? (ideally in Java or Python)