99 - What is Non-local means (NLM) denoising filter?

[@ewang0212]

WOW, so far NLM is the best filter introduced in this series, I like your video by the way, thanks

[@vladimirrakonjac7763]

Hi, do you have any idea if is there an implementation of the Bilateral Filter for OpenGL through GPU and Shaders? Mobile phone real-time game is the subject of usage.

[@awaisnawabi9361]

Hi, Could you please guide me, if I want to do denoising the cell's images and after that I want to use model for segmentation. There are different types of denoising filters. So which type of denoising I use?

[@ayserumeysamohammed4612]

Hi, a killer question: how do you choose a filter for a specific problem? e.g. you state that NL means works well with CT images. What about detecting an object in water?

[@DigitalSreeni]

This is why they invented machine learning!!! Some filters are obvious, for example if you want to detect edges or rounded features. But for the most part it is tough to predict which filter works best at what pixel. Therefore, for segmentation or classification problems you can apply a bunch of filters at every pixel and fit a machine learning model (e.g. SVM or Random Forest) on the training data. Random Forest provides you feature ranking - which filters contributed the most. This is one way to find what works well for a given type of problem.

[@ayserumeysamohammed4612]

@@DigitalSreeni Thanks :) your content is very informative. Good luck with your channel!

[@tonix1993]

@@DigitalSreeni Is there any paper/study on this? thank you

[@stenseenonwuliri7079]

Can these filters denoise colored images because i noticed all your sample images are black and white images. My images are microscopic thin blood smear images and whenever i use any of the filters, it returns a black and white image

[@DigitalSreeni]

Many denoising filters work on single channel so one way to denoising RGB images would be by splitting the channels, denoising, and merging them back.

[@puritynow9397]

Hello Sir. How can I write the code to denoise a bunch of images in a directory

[@DigitalSreeni]

kzbin.info/www/bejne/h6ndqX-Mr7OZmKs

[@vigneshsrinivasan9692]

Why did you have to do np.mean while using estimate_sigma?

[@DigitalSreeni]

Without that you will have 512 values for sigma. I am averaging these values to get the mean. Please look at the documentation for estimate_sigma.

[@rajnikyadav]

Hello Sir, can you please send me the link of this NL- Means paper

[@DigitalSreeni]

A. Buades, B. Coll and J. -. Morel, "A non-local algorithm for image denoising," 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05), San Diego, CA, USA, 2005, pp. 60-65 vol. 2, doi: 10.1109/CVPR.2005.38 Also check out: dsvision.github.io/an-approach-to-non-local-means-denoising.html

[@natashabhandari7449]

Can u send the video for dynamic non local mean filter

[@DigitalSreeni]

Sorry, never tried dynamic NLM.

[@younesshokoohi1720]

thanks for this tutorial . can you explain and implement Residual Unet in a tutorial please?

[@DigitalSreeni]

I'll add Res-Unet to my backlog of training topics.