Reduce Noise! New Way!

[EchoingWhisper]

I just thought of a new (maybe its old but it's new for me) way to reduce noise. Since noise is random, shooting more of the same shots would neutralise it. I think that if we stack the photos, we will get less noise. I'll try it out tomorrow.

 

[Mrgiggls]

Think of noise as static on a TV channel that's not coming in very well (I'm talking about over the air broadcast that your grandparents watched). If you have a noisy image, merging more of the same is only going to give you merged noise. Noise reduction algorithms are designed to analyse the overal tone and luminosity of an area and take pixels and try to remove variances in that tone and luminosity and bring them down to a uniform and smooth level. This is why detail is lost. The pixels are changed to more closely match the neighboring pixels.

I aplaud your spirit of ingenuity but I think if it were that easy, we'd have already been doing it for years.

 

[EchoingWhisper]

Think of noise as static on a TV channel that's not coming in very well (I'm talking about over the air broadcast that your grandparents watched). If you have a noisy image, merging more of the same is only going to give you merged noise. Noise reduction algorithms are designed to analise the overal tone and luminosity of an area and take pixels and try to remove variances in that tone and luminosity and bring them down to a uniform and smooth level. This is why detail is lost. The pixels are changed to more closely match the neighboring pixels.

I aplaud your spirit of ingenuity but I think if it were that easy, we'd have already been doing it for years.

Guess it didn't work.

 

[Sw1tchFX]

Think of noise as static on a TV channel that's not coming in very well (I'm talking about over the air broadcast that your grandparents watched). If you have a noisy image, merging more of the same is only going to give you merged noise. Noise reduction algorithms are designed to analyse the overal tone and luminosity of an area and take pixels and try to remove variances in that tone and luminosity and bring them down to a uniform and smooth level. This is why detail is lost. The pixels are changed to more closely match the neighboring pixels.

I aplaud your spirit of ingenuity but I think if it were that easy, we'd have already been doing it for years.

It IS that easy, and people HAVE been doing it for years.

If you're on a tripod, and you have 10 shots at ISO 1600, the random noise will blend together, however the detail (since it won't be moving) will still remain, because unlike random noise, it will be the only thing that will consistently be in the exact same place in each picture.

I've done it with my D700, in camera with multiple exposure turned on, and it can make ISO 1600 look more like 200. It works, and works very, very well.

 

[L4RRY]

Im not sure but i think this is technology used in sony nex and sony alpha, they make 5 images and then reduce noise... Some people are using it manually (making few pictures and then combine them to have less noise) negative on this is that the images looses sharpness litle bit.

 

[Mrgiggls]

Wow.....I stand corrected. I wasn't aware of image averaging, but a quick Google search shows it to be an effective and popular tool for astrophotography. Thanks Sw1thFX. Always a good day when you learn something new.

My apologies Michael...I spoke before checking my facts.


BTW...here is an interesting article I found on the subject.

 

[EchoingWhisper]

Lol I feel proud. I thought of this without ever reading anything similar. I just tried it and it works, my ISO 6400 looks clean. It's like shooting at a longer exposure with a lower ISO. One thing I couldn't get back though is the highlights.

 

[EchoingWhisper]

Im not sure but i think this is technology used in sony nex and sony alpha, they make 5 images and then reduce noise... Some people are using it manually (making few pictures and then combine them to have less noise) negative on this is that the images looses sharpness litle bit.

You don't actually lose sharpness. Noise increases the look of sharpness. Try increasing noise in Photoshop and you'll realise that the photos look sharper.

 

[JSER]

I just thought of a new (maybe its old but it's new for me) way to reduce noise. Since noise is random, shooting more of the same shots would neutralise it. I think that if we stack the photos, we will get less noise. I'll try it out tomorrow.

Bit hard with windsurfing, motor cross, skateboarding etc etc

 

[Overread]

Far as I know this is how most long exposure noise reduction programs work inside cameras. They take the same length of exposure with the shutter closed right after the first exposure and then remove the noise spots from the second shot from the first (since the second shot should only show black or noise image).

Focus stacking in macro also makes use of this, whilst at the same time stacking the sharper parts of the shot together. And as said astro photography makes extensive use of this method (Esp if you don't have a liquid nitrogren setup to cool your camera for super long exposures).

Also Echo - you needs get out and shoot more

 

[matthewo]

Soo when would you actually use this much. If you take multipule images on a tripod at 1600 and merge them to get a noise reduction image similar to 200 iso. If your using a tripod on a still subject why wouldnt you just shoot at iso 100 and a longer shutter speed?

 

[Alex_B]

This is in fact one standard way of noise reduction in scanners, just do a multiple pass scan and then average the final image.

 

[Overread]

Soo when would you actually use this much. If you take multipule images on a tripod at 1600 and merge them to get a noise reduction image similar to 200 iso. If your using a tripod on a still subject why wouldnt you just shoot at iso 100 and a longer shutter speed?

Normally its used for asto photography where the exposure times are well over 5 minutes if shot at low ISO. Shooting that long results in a massive heat build up on the camera sensor; so they often have to resort to higher ISOs and multiple shots to reduce the strain on the sensor.

 

[matthewo]

Soo when would you actually use this much. If you take multipule images on a tripod at 1600 and merge them to get a noise reduction image similar to 200 iso. If your using a tripod on a still subject why wouldnt you just shoot at iso 100 and a longer shutter speed?

Normally its used for asto photography where the exposure times are well over 5 minutes if shot at low ISO. Shooting that long results in a massive heat build up on the camera sensor; so they often have to restore to higher ISOs and multiple shots to reduce the strain on the sensor.

Ahh that makes sense

 

[EchoingWhisper]

Soo when would you actually use this much. If you take multipule images on a tripod at 1600 and merge them to get a noise reduction image similar to 200 iso. If your using a tripod on a still subject why wouldnt you just shoot at iso 100 and a longer shutter speed?

Another way is to reduce noise if ISO100 is noisy.

Edit: shooting 10 1 second shots would equal to a 8 minute long exposure.