How to remove noise from images

[yogimelayu12]

I employ OpenCV in my teaching. thresholding during image processing. Although I used thresholding, there is still noise. how to get rid of the noise like removing color if size > 100.

[RafaDdS]

Look into morphological filters. It's probably the best option on a binary image such as your example. A closing would be able to remove the noise inside the interest object while an opening would remove true pixels/regions in the outside.