Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

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wornish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Jesus! Photography said:
This is my blog post containing a video guide on how to shoot and edit your picture in order to achieve the absolute zero noise.

Guide to Zero Noise with Median Stacking | Jesus! Photography
Click to expand...

Thanks for this I just tried it and it works great.
Just tried a shot at iso6400 which was very noisy.
Took only 5 shots and it made a huge difference.

Will have a play with the other stacking options.
 
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wornish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Here is an example 5 shots taken at iso6400.
In far from ideal lighting.
100% crop of a small area of the pic

Before Median see the noise
before.jpg


After Median stacking

after.jpg


I will let the shots speak for themselves.
I have learnt something today :)
 
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Geoffc

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Am I missing something here? If you are taking multiple shots to remove noise, why not just take one of longer exposure and lower ISO? I'm sure I've missed the point.


Sent from my iPad using Tapatalk HD
 
Horoscope Fish

Horoscope Fish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Geoffc said:
Am I missing something here? If you are taking multiple shots to remove noise, why not just take one of longer exposure and lower ISO? I'm sure I've missed the point.
Click to expand...
I've heard of median stacking but have never tried it. As I understand it, and too answer your question as best as *I* can, the point is this...

If you pixel peep hard enough all DSLR images will show some noise, even at base ISO. Zoom in to, say, 300% or so and you'll find it. By using median staking you can dramatically increase the Signal to Noise ratio and effectively eliminate *ALL* noise. If you're shooting a static subject, using a tripod anyway and have the correct PP software, I can see how it would make sense to use the technique.
....
 
Marcel

Marcel

Happily retired
Staff member
Super Mod
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

So what if you'd load the exact same shot 5 times and try this, would it do the same?

I know the Fuji X-10 has a feature like this where it takes multiple shots and converts it to jpeg while removing high iso noise.
 
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wornish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Marcel said:
So what if you'd load the exact same shot 5 times and try this, would it do the same?

I know the Fuji X-10 has a feature like this where it takes multiple shots and converts it to jpeg while removing high iso noise.
Click to expand...

The short answer is yes it works with any number of shots of the same subject , each layer must be aligned though. Median just averages each pixel from however many shots you take. Sounds like the x-10 is ahead of the game and does it in camera for JPEGS .

I didn't know this feature existed in PS, there are other stacking options to try as well.
 
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Horoscope Fish

Horoscope Fish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

wornish said:
The short answer is yes it works with any number of the same shot , each layer must be aligned though. Median just averages each pixel from however many shots you take.
Click to expand...
Hold on a sec... I get what you're saying here but I'm confused. Wouldn't the average arrived at using each shot from a five-shot sequence be different than the average arrived at by using the same image file five times over? I thought that was the point of taking additional images... Because the noise will not be perfectly consistent across all frames you wind up with a broader SNR "base" to calculate on using multiple image files and that, theoretically, should mean a more accurate calculation for noise reduction, no?
.....
 
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wornish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Horoscope Fish said:
Hold on a sec... I get what you're saying here but I'm confused. Wouldn't the average arrived at using each shot from a five-shot sequence be different than the average arrived at by using the same image file five times over? I thought that was the point of taking additional images... Because the noise will not be perfectly consistent across all frames you wind up with a broader SNR "base" to calculate on using multiple image files and that, theoretically, should mean a more accurate calculation for noise reduction, no?
.....
Click to expand...
You are correct I changed my post as it was not clear. It only works with multiple separate shots of the same subject.
 
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Geoffc

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Horoscope Fish said:
I've heard of median stacking but have never tried it. As I understand it, and too answer your question as best as *I* can, the point is this...

If you pixel peep hard enough all DSLR images will show some noise, even at base ISO. Zoom in to, say, 300% or so and you'll find it. By using median staking you can dramatically increase the Signal to Noise ratio and effectively eliminate *ALL* noise. If you're shooting a static subject, using a tripod anyway and have the correct PP software, I can see how it would make sense to use the technique.
....
Click to expand...

So I think I actually got it the first time. If you're a normal human being shooting at base ISO or a few stops above on a modern DSLR it will do little to nothing for you. If it's a high noise ISO thing just increase the exposure time so you get back into the better ISO range. It seems more aimed at people who prefer doing taking test shots than real ones :rolleyes:
 
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wornish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Geoffc said:
So I think I actually got it the first time. If you're a normal human being shooting at base ISO or a few stops above on a modern DSLR it will do little to nothing for you. If it's a high noise ISO thing just increase the exposure time so you get back into the better ISO range. It seems more aimed at people who prefer doing taking test shots than real ones :rolleyes:
Click to expand...

For normal humans, and non ISO peepers, shooting in good light it makes no difference :)

But....
It does make a difference when doing high ISO shots in low light conditions when there is no alternative.
if you have no option but to up the ISO to crazy high levels then this could make a huge difference.
 
Horoscope Fish

Horoscope Fish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

wornish said:
You are correct I changed my post as it was not clear. It only works with multiple separate shots of the same subject.
Click to expand...
Okay, I was just making sure I understood how this whole thing works... Not that it's likely I'll try it any time soon.


Geoffc said:
So I think I actually got it the first time. If you're a normal human being shooting at base ISO or a few stops above on a modern DSLR it will do little to nothing for you. If it's a high noise ISO thing just increase the exposure time so you get back into the better ISO range. It seems more aimed at people who prefer doing taking test shots than real ones :rolleyes:
Click to expand...
I'm pretty inclined to agree with your assessment. I guess I'm glad to know about this technique, but I don't see myself using it.
....
 
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Geoffc

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

wornish said:
For normal humans, and non ISO peepers, shooting in good light it makes no difference :)

But....
It does make a difference when doing high ISO shots in low light conditions when there is no alternative.
if you have no option but to up the ISO to crazy high levels then this could make a huge difference.
Click to expand...

If you need the ISO it means you've no tripod which means five different images. Not good for stacking. It can't be used for action at high ISO so I still think it's useless.
 
Jesus! Photography

Jesus! Photography

New member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

thread is on fire! I'm glad you guys liked the tut :)

Theory says that noise will not be consistent in multiple exposures but signal will be. So the more exposures the better elimination of the noise. I've seen wonders with this method even on 25.600 iso (link below)

Rumor says that it was first astrophotographers that discovered the method since these guys shoot high iso all the time, but they don't want a too long exposure so to avoid getting star trails. So they discovered this method in order to be able to shoot in high iso with good speeds and reduce noise in a more effective way.

personally, I even liked it for base iso shots and it immediately became my favorite method for zero noise images. Some subjects/genres that could use this method: Food, interior, architecture, product, landscape. It's a slower workflow and it won't apply in my low budget jobs, but when I have a client looking for the best quality, and theme is eligible, this will be the way.

check this link for some deeper info, and also see why it does not apply to action shots.
A Look at Reducing Noise in Photographs Using Median Blending



 
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wornish

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

Geoffc said:
If you need the ISO it means you've no tripod which means five different images. Not good for stacking. It can't be used for action at high ISO so I still think it's useless.
Click to expand...

Right from the first post it is clear that it doesn't work for moving objects so yes your correct.

also yes being on a tripod also helps as it makes it easy to align different shots.

And ......its not for general use granted.

Again there is a but....


eg taking a night sky shot with stars this technique will make a difference - take 4 or 5 in quick succession and use this technique.

eg. You find an subject in a dark corner in a dark place , no flash, it can make a difference.

I don't write off using different techniques for different circumstances just because it's different - I try to keep an open mind :)
 
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J-see

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

wornish said:
Right from the first post it is clear that it doesn't work for moving objects so yes your correct.
Click to expand...

My version of PS doesn't have these options I fear but I was playing with the old median filter, applying it to a copy and then blend that in with the original. Even with that prehistoric technique I can improve my noise.

Posts like these make me buying the new PS almost inevitable. ;)
 
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Geoffc

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

wornish said:
Right from the first post it is clear that it doesn't work for moving objects so yes your correct.

also yes being on a tripod also helps as it makes it easy to align different shots.

And ......its not for general use granted.

Again there is a but....


eg taking a night sky shot with stars this technique will make a difference - take 4 or 5 in quick succession and use this technique.

eg. You find an subject in a dark corner in a dark place , no flash, it can make a difference.

I don't write off using different techniques for different circumstances just because it's different - I try to keep an open mind :)
Click to expand...

In reality I'm just being mischievous and I'm sure it's useful for certain applications :)
 
F

Felisek

Senior Member
Re: Guide to Zero Noise with Median Stacking - Photography & Photoshop CC Tutorial

As a scientist working with statistic and signal processing, I though I might add a few comments to this interesting thread.

Firstly, @wornish, if I understand your example correctly, it is rather misleading. The top picture is a single exposure of 1/15 s, correct? The bottom picture is a stack of five exposures, so it contains information from 5 * 1/15 s = 1/3 s, five times longer. Regardless of the median stacking, the bottom picture has a much longer effective exposure, so, obviously, the noise will be lower. But perhaps I misunderstood your example.

I think the important question here is the one asked by @Geoffc. Consider five shots of 1/15 s and one shot of 1/3 s, but with lower ISO. They should have collected the same amount of photons, so why would the median stack resulted in lower noise?

This is because the median is not sensitive to outliers, i.e., speckles or hot pixels. If you open your shutter for 1/3 s and collect all the light, there will be photons with unusually high energy coming occasionally, creating what we see in the image as speckles. If you divide this exposure into five, the chances are that in the given pixel the speckle event will happen only once, maybe twice. The median will help eliminating these "outliers".

Imagine you observe one pixel in one colour channel. Let us assume that the typical value of this pixel in this channel is 65 (you could establish this taking a long exposure at very low ISO). Now, let's take five short pictures. We can get values like these:

65, 68, 61, 95, 64

The numbers marked in black represent typical noise, while the 95 in red is a spurious event. Now, if you took one longer exposure instead, the result would be the mean of these numbers, about 71, which is brighter than the typical value of 65. If you take the median of these five numbers, the result will be 65, close to a typical value.

The median stacking can help you lower some types of noise, namely speckles and hot pixels. It will not eliminate this type of noise entirely, it will not eliminate background Poisson noise, thermal noise and other sensor artefacts, it will not lead to zero noise, as claimed in the title of the thread. I'm sorry guys, but you cannot beat physics and statistics. Noise will be always present in your pictures.
 
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