How to filter noise images?

[tiho_bg]

Hallo,

I would like to filter noise images. Here is one of my images and the result after filtering the image with the Vision Assistant. I would like to filter the separated cells as much as possible but the noise generated by the fluid flow as a background could not be filtered. I would like to delete the the lines of the fluid flow from the image. Could you please assist me or advise me? Thank you!

[altenbach]

Since you are using modules, the machine vision forum might be more appropriate for your question. We also cannot tell what kind of settings you are using in the vision assistant. Typically a screenshot of the panel does not really tell us much.

Still, a greyscale image is just 2D data and it is possible To use plain LabVIEW tools to do all processing. Obviously, simple thresholding is not suitable but there are other obvious distinction between objects and background. In general, the more we know about the objects, the better the detection. Are the objects always the same size? Is the background always horizontally banded?  Do you really need an image output or would just e.g. counting the objects be sufficient?

[altenbach]

Here's a quick attempt subtracting a least absolute residual polynomial fit from each row, followed by thresholding at 30.

[altenbach]

Subtracting a background obtained by convoluting with a suitable horizontal kernel followed by another filter to remove single spikes seems to work quite well. You still need deal with edge effect on both sides and maybe tweak the two kernels, but overall it works quite well and is fast.