Luminance noise, color noise and noise reduction

[The_Traveler]

Preparing for a lecture tomorrow night and thought this image might be interesting.
This was taken with an EP3 on a tripod at 6400 ISO and is at 100% crop

I used Noiseware by Imagenomics to remove all the color noise to show the luminance noise and so on.
It seems an almost total absence of color noise (yay Olympus) but a good deal of luminance noise that was mainly correctable. I didn't work hard at this to try different algorithms but the Noiseware worked well for an example.

 

[KmH]

I've been using Imagenomic's Noiseware Pro for over 15 years now.
And that's about how long I've used their Portraiture retouching software too.

 

[JustJazzie]

Interesting! I really should learn a bit more about correcting noise. Apertures NR slider was utterly worthless. Now that I have Lightroom I slide the sliders until it looks corrected but have no idea what I'm doing!

 

[Overread]

Most RAW converters remove colour noise in their default settings; just like they also apply a moderate level of sharpening so that you've a clear photo to work with (go ahead try turning off all sharpening on your RAWs).

So often as not by the time you read 3rd party noise removal software you've already lost most of the colour noise unless you were dealing with a very noisy shot.


Far as I can tell with noise removal software is that there are LOTS of options, each of which works a little differently, but each of which is generally able to perform to a similar standard. There was an article published a few years back which extensively tested the various options and found that yes there were differences; some certain patterns of noise could be beaten better by some software over others; but in the end they were marginal differences and the variety of conditions meant that to gain the advantage you'd spend a lot of time in each software suite comparing the end results; tweaking and fighting for tiny difference - just not worth it for most photographers (esp once you out put to internet or print)

 

[KmH]

Noise reduction and image sharpening are 2 sides of the same coin.
If you reduce image noise you also effect sharpness, and visa versa.
The goal is to achieve a careful balance of both, if a photo requires image noise reduction.

Bruce Fraser covers the whys and hows of noise reduction in his excellent book:
Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom (2nd Edition)

Note all the image editing books on the shelf in the posted photo.

 

[Braineack]

Here's how I correct noise:

 

[The_Traveler]

Noise reduction and image sharpening are 2 sides of the same coin.
If you reduce image noise you also effect sharpness, and visa versa.
The goal is to achieve a careful balance of both, if a photo requires image noise reduction.

Bruce Fraser covers the whys and hows of noise reduction in his excellent book:
Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom (2nd Edition)

Note all the image editing books on the shelf in the posted photo.

I sort of agree; I think that, in situations where there is adequate signal to noise ratio, reducing noise removes what looks like detail but is really not.
Both noise reduction tools and image sharpening tools look for edges; it's what happens afterwards that is sort of different.

I thought I knew sharpening pretty well but in preparation for this presentation, I read Bruce Fraser's book pretty extensively and repeatedly - and with varying degrees of confusion.
Someone who uses a relatively modern camera and who works on a tripod and/or controls their exposures in a studio can pretty much forget about noise because they can make certain that their exposures guarantee a good signal to noise ratio. (ETTR and all that)
It is those of us who work in varying conditions and uncontrollable exposures who suffer with this problem.

IMO, there is no clear universal approach that will guarantee sharpening because each image is so different, the strategies must vary from image to image and the interaction of all the factors of amount, radius, threshold, detail and luminance noise in any particular spot are are almost unpredictable.
There are so many variables that the only potential approach is to learn tools and techniques and try them repeatedly until one gets good.
Most of the actual photos in his book are hopeless as aids except in extreme cases; they are too small and indistinct to really see any subtle points he is trying to make.
The book would have been infinitely better and more instructive if it had come with downloadable images so we could look at them on the screen at various magnifications.

In other words, I started the book, thinking I had a decent hold on this and came away more confused than when I started.

 

[oldhippy]

Not big on skills, but that said, here's my method. Using Lightroom in the Develope mode. Zoom image to 100 %. Use sharpen slider until grain appears. Use noise slider to reduce . Balance for best image.
This is best I can do at this point. Later. Ed