thanx dinasset will try again tomorrow. Just saw your post
Thank you too Iain.

I love this noise reduction filter. This one below used the default setting, there are still some noises. How to use the fine and coarse slides? Is it first to move the fine slide and then fine tuned by using the coarse slide?

The 'fine' slider is the main slider and reduces small size noise. The 'coarse' slider removes larger noise blotches. The fine slider overlaps with the coarse slider a bit so both sliders work on medium sized blotches.

Hi Iain,
Could you explain what's done in the filter?

I can guess it is the Non Local Means running using Multi Scale Approach, am I right?

I'm not at home at the moment so I can't check the details, but if I remember correctly, by default, it does a non-local means pass with a small search radius, then resizes the image by ⅓ and does another nl-means pass but with a larger search radius. The details for the first pass are combined with the upsized second pass.

The advantage to this approach is you get good results for large noise blotches without the speed penalty of a large search radius on the full size image.

Edit: The resizing by ⅓ is my work around to reduce artefacts. I add pixels to the edges so the image dimensions are divisible by 3. When resizing back to full size I use my own resizing hack to make sure known pixels are in the centre of the 3x3 block the was combined for the downsize.

I can't download photos, don't know why, bi=ut it's really cool. I used noiswere communitor of something like this before, but your's I like more