Dual ISO - massive dynamic range improvement (dual_iso.mo)

[Canon eos m]

One more comparison. This time between raw and dual-iso in movie-mode. two extracted dng,s from raw and dual-iso raw-moviefiles. Even if dual-iso benefits most from high contrast scenes there is still one or two steps better dynamic range with dual-iso even in more evenly lit situations. Pretty amazing since regular raw is already amazingly good.

Danne, I cannot spot the difference between the single & dual iso versions except in the last 2 crops. There has to be something I am missing. Could you please Dropbox the unprocessed RAW's.

[Danne]

There is hardly any visible difference in the first pictures as you can see which is a good thing. It is when you start to push the shadows out that you start to see a subtle difference, This gets more visible when you shoot in contrasty situations but there is still a difference, slightly.
The movie raws are about 350mb each, to big to upload from where I sit atm. You can play around with two extracted dng-files if you like . Link below.
https://docs.google.com/file/d/0B4tCJMlOYfird3RMV0l5c2c0RzQ/edit?usp=sharing

@Ilias G. I don,t see anything wrong with the single iso-file?

[Audionut]

I've managed to hack the source to work with 7D.

edit:  removed, to many problems.

Don't bug the devs about my build.  I've created it for the sole reason of people with 7D's being able to test this feature.  It comes with no warranty or support (but I'll help where I can).

[Alex Roman]

There is hardly any visible difference in the first pictures as you can see which is a good thing. It is when you start to push the shadows out that you start to see a subtle difference, This gets more visible when you shoot in contrasty situations but there is still a difference, slightly.
The movie raws are about 350mb each, to big to upload from where I sit atm. You can play around with two extracted dng-files if you like . Link below.
https://docs.google.com/file/d/0B4tCJMlOYfirTTRETlpaQnZVMG8/edit?usp=sharing

@Ilias G. I don,t see anything wrong with the single iso-file?

Danne, it's amazing, thanks. Video is getting better and better (whitefix?)... Only some blur in highlights so it seems to begin to be pretty usable now. Is that interpolation becomes less noticiable with smaller interval (i.e 400-100)?

[Danne]

Have not done any serious filming yet but it could be nice in certain situations. Nighttime, citylights, maybe real estate filming getting the highligts from windows and so on. When taking stills it works really well.

[Alex Roman]

Certainly is a huge step taking stills! On the other hand, i think the real revolution comes with (pretty) usable dual iso video function -which from what i see is taking giant steps in fews days-

Looking forward to see more dual iso clips (no that agressive interval ones?) 

[Alex Roman]

...maybe real estate filming getting the highligts from windows and so on. When taking stills it works really well.

I also see amazing serious cinema 14-stops DR beautifully rendered imagery... 

[Danne]

When I made this comparison with 100-6400 and regular 100 iso one realize there has to be more shadows regained than 2 extra stops. By dividing in such a big interval i,d argue that you suddenly gained about 4-5 extra steps. I was able to lift the shadows to the extent I couldn,t go any further with the lightroom exposure slider. Could have used the brushes though but still.
These shots are even converted with the old converter.


dng 100-6400 original



dng 100-6400 processed


dng 100-6400 cropped


cr2 iso 100 original


cr2 iso 100 processed


cr2 iso 100 crop

[Pelican]

There is a working build for the 7D in the 7D alpha2 topic.
The produced files (ISO 100/1600 and ISO 1600/100):
http://pel.hu/down/100_1600_7D.CR2
http://pel.hu/down/100_1600_7D.DNG
http://pel.hu/down/1600_100_7D.CR2
http://pel.hu/down/1600_100_7D.DNG

[dadinio13]

Last raw2dng.exe stops at frames 493 for all my footages with the error : mallocxels.
look at this :

i have downloaded raw2dng.exe many times i was thinking it was a browser cache issue but is not...
any ideas ? please !

[IliasG]

The movie raws are about 350mb each, to big to upload from where I sit atm. You can play around with two extracted dng-files if you like . Link below.
https://docs.google.com/file/d/0B4tCJMlOYfirTTRETlpaQnZVMG8/edit?usp=sharing

@Ilias G. I don,t see anything wrong with the single iso-file?

Thanks for the samples.

The problem I see in your 200% crop of the single ISO file is a magenta cast at the darks of the sculpture and some clipping. Which is much less present with my conversions using Rawtherapee.

What was the lighting during the shots ? I have a hard time finding a correct WB.
Was it consistent in color and intensity ?. Because if it was a candle we cannot come at a valid conclusion comparing only two single frames.

[Danne]

How can you whitebalance rawmovies. Rawmovie converted with latest raw2dng.exe. Dngs provided in the link. The test was aimed for noisecomparison. Thanks for watching

[yanone]

Hi everyone,

somewhere here in this thread I read that the 5D3 produces less noise in dark areas with a higher ISO, therefore the dark areas are recovered from high ISO while light areas are recovered from low ISO.

I did some tests today and filmed the same scene (without Dual ISO) in ISO steps from 100 to 3200 and adjusted the exposure accordingly.
After running the DNGs through ACR in AE I can't see this effect. The lowest ISO still has the least noise in recovered dark areas. Starting at ISO 800 there's a noticeable shift towards magenta in the shadows.

In other words: I don't understand the Dual ISO. What did I miss?
As I see it lowest ISO is best for highlights and for shadows.

In the sample images you see the background in dark shadow under a roof, front in sun light.


ISO 100


ISO 800


ISO 3200

[Canon eos m]

Hi Yanone, I think the point is missed here. In normal circumstances (read 10 bit and below situations) you should use the plain RAW mode for still and video. Extreme situations (read 11 bit and above) require extreme treatment. This is what Dual-ISO is all about. Faced with a high Dynamic Range situation (facing the sun, bright reflection), it is better to use this functionality to capture and recover most of the shadows and highlights that would otherwise be lost forever. It is just a special tool to be used in special situations.

[IliasG]

Hi everyone,

somewhere here in this thread I read that the 5D3 produces less noise in dark areas with a higher ISO, therefore the dark areas are recovered from high ISO while light areas are recovered from low ISO.

I did some tests today and filmed the same scene (without Dual ISO) in ISO steps from 100 to 3200 and adjusted the exposure accordingly.

In other words: I don't understand the Dual ISO. What did I miss?
As I see it lowest ISO is best for highlights and for shadows.

(Faulty step in bold).

You missed the fact that to take the effect of cleaner darks with hi ISO you have to keep the exposure constant between shots .. and exactly is what dual-ISO does ..

[Canon eos m]

IliasG could you elaborate the concept in some more detail.

[IliasG]

How can you whitebalance rawmovies. Rawmovie converted with latest raw2dng.exe. Dngs provided in the link. The test was aimed for noisecomparison. Thanks for watching

To make fair noise comparisons we have to compare shots at the same exposure (light inconsistency can give faulty conclusions) and the compared images been at the same contrast, saturation, WB and detail levels ...

Your uploaded dual ISO DNG is named 6400-100 .. wasn't your shot at 6400-1600 ??

Can you declare what lighting you used ??.
And upload the first frames of each session if possible, I would like to have them because the Black Level data is calculated on the start of each session.

[Danne]

Wrote wrong. Dual iso was shot 6400-1600, regular shot 1600, same lighting, same settings on the camera same processing in lightroom. Could upload the first dual iso dng later today. The other dng is the first one I believe? I used a lightbulb

[yanone]

Hi Yanone, I think the point is missed here. In normal circumstances (read 10 bit and below situations) you should use the plain RAW mode for still and video. Extreme situations (read 11 bit and above) require extreme treatment. This is what Dual-ISO is all about. Faced with a high Dynamic Range situation (facing the sun, bright reflection), it is better to use this functionality to capture and recover most of the shadows and highlights that would otherwise be lost forever. It is just a special tool to be used in special situations.

Right. I do consider my sample scene an extreme lighting situation. Front in bright sunlight with reflections, background in dark shadow. The background used to be almost black in the undeveloped DNG, front used to be very bright.

You missed the fact that to take the effect of cleaner darks with hi ISO you have to keep the exposure constant between shots .. and exactly is what dual-ISO does ..

Hmm, I see. Now I'm curious to actually try the Dual ISO. If I get a noticable difference, I'll post an update.

[IliasG]

IliasG could you elaborate the concept in some more detail.

Alex explains it in http://acoutts.com/a1ex/dual_iso.pdf page 1-2 and gives some links ..

http://www.guillermoluijk.com/article/nonoise/index_en.htm (it's a dead link for the moment, let's hope for recovery)
http://www.dpreview.com/forums/post/28749589
http://www.dpreview.com/forums/post/28750076

The explanation for the decreased of noise at the dark areas at hi ISOs is that there is electronic noise at the late stages (transfer lines, DAC) after ISO amplification which noise is constant. If we feed the DAC with low signal (ISO100) lets say the noise is equal to this signal (SNR 1.0). If we feed it with amplified signal (ISO 1600) then the signal is 16 times stronger while the noise remains constant so SNR is 16.0 .. This with an ideal sensor and first stage electronics with no noise. In practice there is first stage noise also (but lower than late stage) so the SNR becomes around 8.0 and we gain 3 stops DR instead of 4 ..   

 

[yanone]

Here's the scene with Dual ISO 100/1600.
Indeed, the dark background looks fantastic. But it's about the only detail that looks nice in this picture. (Same workflow: raw2dng.exe (July 22nd) -> AE -> ACR) 

[Alex Roman]

Ouch! 

[Danne]

@Ilias

updated my link now containing the first dngfile from both of the examples. base-iso 1600 for both files. 6400-1600 on the dual-iso. (reversed due to converting issue, still base-iso 1600 though). Lighting and camerasettings identical for both shots.

https://docs.google.com/file/d/0B4tCJMlOYfird3RMV0l5c2c0RzQ/edit?usp=sharing

//D

[arrinkiiii]

There is a working build for the 7D in the 7D alpha2 topic.
The produced files (ISO 100/1600 and ISO 1600/100):
http://pel.hu/down/100_1600_7D.CR2
http://pel.hu/down/100_1600_7D.DNG
http://pel.hu/down/1600_100_7D.CR2
http://pel.hu/down/1600_100_7D.DNG

THANKS Pelican !!! U ROCK 

[Shizuka]

@Ilias

updated my link now containing the first dngfile from both of the examples. base-iso 1600 for both files. 6400-1600 on the dual-iso. (reversed due to converting issue, still base-iso 1600 though). Lighting and camerasettings identical for both shots.

https://docs.google.com/file/d/0B4tCJMlOYfird3RMV0l5c2c0RzQ/edit?usp=sharing

//D

Do you even gain any sort of benefit doing dual iso with recovery ISOs above 1600 (APS-C, 5D2) / 3200 (5D3+) - also known as the point where the read noise no longer decreases?

The theory suggests that 100/[200,400,800,1600] only make sense, and 100/3200 only if you've got a 5D3.