Noise Reduction in Deep Sky Images
Noise Reduction in Deep Sky Images
I recently had some sessions which were going to be potentially disrupted by intermittent cloud and decided to use the opportunity to capture some frames with a Luminance filter and experiment with different exposures - 40x120s and 60x60s in this case. At processing, many frames were rejected due to degradation by cloud. The resultant stacks were therefore noisy. I came across a piece of software, called Neat Image, which provides an automated workflow for reducing noise in images. https://ni.neatvideo.com/download - runs on Windows. MACOS, Linux and has a plug-in for Photoshop. The demo edition will only output 8-bit JPG files. On starting the software, there is a handy link to a tutorial video.
Here are the comparisons - the noise reduction took 4 or 5 clicks and no decisions needed to be made about settings. Click on the images to better see the comparison.
To date, I haven't been able to get close to these results using the noise reduction in GIMP, which is probably down to user ignorance rather than the software.
Neat Image is worth a look if there is a requirement to clean up some noisy images.
Dave
Here are the comparisons - the noise reduction took 4 or 5 clicks and no decisions needed to be made about settings. Click on the images to better see the comparison.
To date, I haven't been able to get close to these results using the noise reduction in GIMP, which is probably down to user ignorance rather than the software.
Neat Image is worth a look if there is a requirement to clean up some noisy images.
Dave
Re: Noise Reduction in Deep Sky Images
Dave,
Great write up! I like your "compare and contrast" style.
I too have found noise-reduction to be woefully inadequate. I use GIMP's "selective Gaussian blur" followed by sharpening, not the other way around. I downloaded Neat a few months ago. My impression was that it did a fine job, better than GIMP, but the learning curve is steeper.
Perhaps you could put together a short tutorial on Neat for lame-brains like me.
Thanks!
Brian
Great write up! I like your "compare and contrast" style.
I too have found noise-reduction to be woefully inadequate. I use GIMP's "selective Gaussian blur" followed by sharpening, not the other way around. I downloaded Neat a few months ago. My impression was that it did a fine job, better than GIMP, but the learning curve is steeper.
Perhaps you could put together a short tutorial on Neat for lame-brains like me.
Thanks!
Brian
Re: Noise Reduction in Deep Sky Images
Here is a rapid tour. The image used was a stack of 40 x 120s exposures with a luminance filter, captured with thin cloud deteriorating over time. Hence the noisy image.
Start Neat Image and ensure Beginner Mode is selected at top right.
On the Input Image tab, click Open input image.
On the Device Noise Profile tab click Auto Profile then Auto Fine-Tune.
On the Output Image tab click Save output image. The image name will have _filtered appended.
By clicking on the Filtered image in the application it is possible to 'blink' between filtered and original.
By selecting Advanced Mode when loading the application a full set of controls become available. As far as i can work out, the Noise Levels presented in Advanced are related to the unsharp mask radius in PhotoShop & GIMP which again are related to Registax's pixel radius Layer 1 (small pixel sharpening) up to Layer 6 (larger pixel sharpening).
The tutorial videos at the Neat Image site give an interesting explanation of all of this.
Dave
Start Neat Image and ensure Beginner Mode is selected at top right.
On the Input Image tab, click Open input image.
On the Device Noise Profile tab click Auto Profile then Auto Fine-Tune.
On the Output Image tab click Save output image. The image name will have _filtered appended.
By clicking on the Filtered image in the application it is possible to 'blink' between filtered and original.
By selecting Advanced Mode when loading the application a full set of controls become available. As far as i can work out, the Noise Levels presented in Advanced are related to the unsharp mask radius in PhotoShop & GIMP which again are related to Registax's pixel radius Layer 1 (small pixel sharpening) up to Layer 6 (larger pixel sharpening).
The tutorial videos at the Neat Image site give an interesting explanation of all of this.
Dave
Re: Noise Reduction in Deep Sky Images
Wow, thank you for this find, Dave. This does a much better job than wavelet denoise in GIMP (or at least the way I have been using it).
Don
Don
Re: Noise Reduction in Deep Sky Images
Thanks Don. Yes, a very useful piece of software which produces consistent results for little effort.
Dave
Dave
Re: Noise Reduction in Deep Sky Images
Post is 6 months old but here now too on Neat Image Pro and it is indeed really great. It beats a program like Topaz Denoise AI by miles.
The results are way more natural due to the many settings. All in all it looks way less "synthetic" then Topaz.
Menno
The results are way more natural due to the many settings. All in all it looks way less "synthetic" then Topaz.
Menno
Re: Noise Reduction in Deep Sky Images
Menno
I select Advanced Mode at top right which gives more options in Noise Filter Settings. This seems to give me satisfactory results.
Dave
I select Advanced Mode at top right which gives more options in Noise Filter Settings. This seems to give me satisfactory results.
Dave
Re: Noise Reduction in Deep Sky Images
Hi Dave
Yep, I use that.
And also no profiles but the Noise Filter Settings itself.
Btw, the current version is 8.6.0.
Menno
Yep, I use that.
And also no profiles but the Noise Filter Settings itself.
Btw, the current version is 8.6.0.
Menno
Re: Noise Reduction in Deep Sky Images
I have had good results with this on DSOs where there is a large enough area to place the sample box that has no image i.e. galaxies, clusters and so on. Where it will fall down is when the whole frame is image i.e. nebula and star fields. I have not tried this but I guess if you took a single frame close to the target in a clear area, you could take a sample from that and import it via the Load Profile tab? Could one build a noise library and if so what would be the defining variables?
Colin
Colin
Re: Noise Reduction in Deep Sky Images
Colin
The denoise worked well for the M31 image below. I have found it doesn't work well on rich star fields (think NGC7000 region) and images captured with wide angle lenses (rather than scopes). Where Neat does complain I accept what is offered and take whatever improvement is given.
Dave
The denoise worked well for the M31 image below. I have found it doesn't work well on rich star fields (think NGC7000 region) and images captured with wide angle lenses (rather than scopes). Where Neat does complain I accept what is offered and take whatever improvement is given.
There is a user donated library of noise profiles https://ni.neatvideo.com/download/noise-profiles plus some profiling info https://ni.neatvideo.com/download/calibration-target.Could one build a noise library and if so what would be the defining variables?
Dave