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Author Topic: ZERO NOISE technique  (Read 311551 times)
Guillermo Luijk
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« Reply #260 on: August 22, 2008, 04:46:54 AM »
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With the mask technique (negate of the over-exposed image to the alpha channel of the negative corrected over-exposed image) which is described in the PS tutorial, I don't get the same amount of perfect gradient in the spot light area in comparison of your ZN software.

My experiment produces the mask and blend the original image with a threshold ratio. So I don't thing it's exactly the same result than your software, or maybe I've done something wrong with the mask generation.
Surely they will never be 100% the same since there are always differences in implementation and rounding values. The important thing is if the solution works and provides a good result.

I have introduced progressive blending since just a small radius: 2 or even 1, will produce transition areas of 2+1+2=5 or 1+1+1=3 pixels wide with a smooth gradation between the images, usually enough to produce a soft effect in the border areas but still keeping most of the pixels genuine, i.e. coming from just one image to be optimum in noise reduction and avoid any loss of sharpness. In my example 98,6% pixels were kept genuine.


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I've been using your "lounge" raw images for my test, so for your sensor which is the best blending ratio?
The 350D saturates at 4095 what makes me think (this is just an hypothesis) that its ADC actually clips the analogue output from the ISO amplifier making 350D's RAW files very linear up to saturation (at the cost of losing some highlight information captured by the sensor of course) because they have actually already been clipped to some threshold. That's why we can be very demanding with those sample images where very high thresholds can be set for blending.

I am not sure if other cameras where saturation does not reach the maximum of the RAW file range (for instance the 5D and 400D sat points are around 3500) are so linear close to saturation so they would need a lower threshold. The optimum threshold value cannot be calculated since it's hardware dependant; I have a feeling it could be kept very high for most situations but everyone should check how his camera works. I only have my modest 350D to do tests and it shows a very linear response in the whole range up to saturation.


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Could you shared your new algo for the "relative exposure calculation", so I can update my code.

Are you planing to release the code source when you hit version 1.0?
That new alg is still just in my mind, but it consists in calculating an accumulative array of relative exposures. For each pixel pair, the relative exposure is calculated, weighted by the level of exposure of those 2 pixels, and then fed into the array with the index according to the relative exposure calculated. In the end we just calculate the median of the statistical distribution obtained. I think it will work fine.

I will keep the new code secret (there is not too much to hide anyway) since the plan in the end is to translate the entire code to a C/C# application with the possibility of a RAW DNG output that could be then developed on the user's favourite software. The two fellows that code in C are still on vacation, I am just starting with VS C#.

I insist again that if someone is reading this that can use the Adobe DNG SDK to produce a DNG file from scratch just contact me.


BR
« Last Edit: August 22, 2008, 05:03:15 AM by GLuijk » Logged

Hening Bettermann
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« Reply #261 on: October 30, 2008, 03:46:14 PM »
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Hi Guillermo!

I am looking forward to use your promising software! After studying the english article, I have a question:

The white balance should be the same in both shots. Would it be sufficient to adjust this post capture in the raw state? The white balance is the one exposure parameter that I prefer the camera to do automatically, since I can not see how I can do it better.

Despite my Zero Spanish, I also tried to extract some information from the tutorial, based on the pictures. Concerning fig. 4, 5 and 6: Does Zero Noise require to define the white balance based on an area in the actual picture?

Kind regards - Hening.
« Last Edit: October 30, 2008, 03:46:47 PM by Hening » Logged

Guillermo Luijk
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« Reply #262 on: November 03, 2008, 09:36:44 PM »
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Quote from: Hening
Hi Guillermo!

I am looking forward to use your promising software! After studying the english article, I have a question:

The white balance should be the same in both shots. Would it be sufficient to adjust this post capture in the raw state? The white balance is the one exposure parameter that I prefer the camera to do automatically, since I can not see how I can do it better.

Despite my Zero Spanish, I also tried to extract some information from the tutorial, based on the pictures. Concerning fig. 4, 5 and 6: Does Zero Noise require to define the white balance based on an area in the actual picture?

Kind regards - Hening.

Hi Hening, the white balance in Zero Noise can be set:
- Camera: will take the camera's WB embedded in the RAW file. Not very recommended if you used auto, but you can try it and see what happens.
- Coeffs: linear multipliers for the RGB channels (not very intuitive)
- Preset: presets
- Patch: choose a rectangular or circle patch and WB will be calculated according to it. IF YOU SET THIS PATCH COVERING THE ENTIRE IMAGE, YOU WILL GET AN AUTOMATIC WB WITHOUT THE PROBLEMS THAT CAMERA'S AUTO WB CAN HAVE, so this could be a good option for you.

BR
« Last Edit: November 03, 2008, 09:37:28 PM by GLuijk » Logged

Hening Bettermann
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« Reply #263 on: November 05, 2008, 06:44:13 PM »
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Hi Guillermo,

thank you for your reply. - I can not quite see how this solves the problem. Make the patch cover the whole image - which one? The zero or the +4? The problem (with the camera AWB) as I see it is that light may shift between the 2 shots - So I thought one could adjust the one of them to the other post capture in the raw state before merging?

Kind regards - Hening.
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Guillermo Luijk
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« Reply #264 on: November 06, 2008, 06:49:03 AM »
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Quote from: Hening
I can not quite see how this solves the problem. Make the patch cover the whole image - which one? The zero or the +4? The problem (with the camera AWB) as I see it is that light may shift between the 2 shots - So I thought one could adjust the one of them to the other post capture in the raw state before merging?
Any of the shots is OK, but the most exposed is recommended to set the patch since it will have less noise and WB calculation will be more accurate. Don't worry about its blown areas since they do not participate in the WB calculation. Once the multipliers have been calculated they will be applied to the two shots so WB will be fine.

Light in the scene should not shift between your shots, why? you have to shoot them one right after the other, not wait for an hour  

BR

PS: BTW we already found someone who can build a DNG RAW file from RAW data. A version of Zero Noise with a 16-bit DNG output free of noise is nearing. I.e. the user puts several RAW files and the program will mix them into a noise free RAW file that everyone will develop and/or tone map using his favourite software.
« Last Edit: November 06, 2008, 07:21:50 AM by GLuijk » Logged

Hening Bettermann
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« Reply #265 on: November 06, 2008, 04:18:51 PM »
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Hi Guillermo!

Thanks for your answer!

>Light in the scene should not shift between your shots, why? you have to shoot them one right after the other, not wait for an hour  

I agree: light should not shift, but you know, up here in the North (Oslo), light is so unbehaved, it DOES shift, and it does not take it an hour to do so, it can do it i a split second!    A typical shooting situation for me is that I stand behind the tripod, one hand on the cable release, waiting for the sun to peep through the clouds!

If, on the other hand, I am lucky enough to catch the same light for 2 consecutive exposures, then what is wrong with auto white balance? I thought the problem was that the automatism would apply 2 different white balances to shots due to light shift? But I have no technical understanding of how the automatism works, and I am open to learn.

(So far, I am satisfied with the result: I remember a day when I was shooting in the same place from about noon into the afternoon. Viewed one at a time, the images looked all natural. However, viewed side by side, those taken near noon were clearly more blue than those taken later in the afternoon. So the automatism does - fortunately - not wipe out the natural color shift in daylight entirely.)

>PS: BTW we already found someone who can build a DNG RAW file from RAW data. A version of Zero Noise with a 16-bit DNG output free of noise is nearing. I.e. the user puts several RAW files and the program will mix them into a noise free RAW file that everyone will develop and/or tone map using his favourite software.

That is GREAT news, and CONGRATULATIONS!  

Hening.
« Last Edit: November 06, 2008, 04:22:12 PM by Hening » Logged

Guillermo Luijk
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« Reply #266 on: November 06, 2008, 05:18:36 PM »
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Hi Hening, automatic white balance can never balance equally two different images if there are spatial differences in hue between them, i.e. if not all 100% of the surface of the image changes equally in white balance from one situation to another which is the common case. That is why any automatic white balance algorithm can be considered 'best effort' for these kind of situations.

I don't recommend to use camera's automatic white balance in Zero Noise, but you can do it: just select automatic WB in your camera and set Camera's WB in ZN, and see if the result is fine.

You can alternatively try DCRAW's automatic white balance by setting -a in the DCRAW command line dialog box, and each RAW file will be developed with DCRAW's auto WB algorithm. I did it over my example scene and you can see some slight differences in white balance (when they all should be the same):



When doing so it's however almost mandatory to set some progressive blending to avoid visible colour steps in the transitions:



BR
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MichaelEzra
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« Reply #267 on: November 07, 2008, 06:50:06 AM »
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Guilermo, this is really great news!!!
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Hening Bettermann
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« Reply #268 on: November 07, 2008, 12:08:56 PM »
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Guillermo, thanks for your reply and instruction. Hening.
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« Reply #269 on: November 23, 2008, 07:38:53 AM »
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Quote from: GLuijk
PS: BTW we already found someone who can build a DNG RAW file from RAW data. A version of Zero Noise with a 16-bit DNG output free of noise is nearing. I.e. the user puts several RAW files and the program will mix them into a noise free RAW file that everyone will develop and/or tone map using his favourite software.

Any idea when you'll have this new version ready?  I can't wait!

John
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Guillermo Luijk
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« Reply #270 on: December 09, 2008, 09:33:47 AM »
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Any idea when you'll have this new version ready?  I can't wait!
In the last two days I adapted Zero Noise to work with undemosaiced RAW data, and it worked fine (in fact it's even easier than making it work with demosaiced data). I have also improved the routines to calculate the relative exposure between the shots.

I have just sent the resulting RAW blend (18MB TIF) (it's linear data, it will display very dark if not assigned to a linear gamma=1.0 profile in PS) to a colleage to embed it into a 16-bit DNG file just to offer the resulting noiseless high dynamic range RAW file here for download.

It will be a Zero Noise HDR virtual RAW containing a lossless unprocessed blending of two Canon EOS 350D RAW files shot 4 stops apart:
   ─ Standard non demosaiced DNG
   ─ Free of noise shadows
   ─ 16 bits equivalent bitdepth
   ─ 12 stops real dynamic range

This was the scene:



And these are the RAW histograms of the two original files and the resulting virtual RAW:



The program will take a bit longer to be ready.

BR
« Last Edit: December 09, 2008, 10:02:25 AM by GLuijk » Logged

Ben Rubinstein
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« Reply #271 on: December 09, 2008, 11:23:19 AM »
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Quote from: GLuijk
In the last two days I adapted Zero Noise to work with undemosaiced RAW data, and it worked fine (in fact it's even easier than making it work with demosaiced data). I have also improved the routines to calculate the relative exposure between the shots.

I have just sent the resulting RAW blend (18MB TIF) (it's linear data, it will display very dark if not assigned to a linear gamma=1.0 profile in PS) to a colleage to embed it into a 16-bit DNG file just to offer the resulting noiseless high dynamic range RAW file here for download.

It will be a Zero Noise HDR virtual RAW containing a lossless unprocessed blending of two Canon EOS 350D RAW files shot 4 stops apart:
   ─ Standard non demosaiced DNG
   ─ Free of noise shadows
   ─ 16 bits equivalent bitdepth
   ─ 12 stops real dynamic range

This was the scene:



And these are the RAW histograms of the two original files and the resulting virtual RAW:



The program will take a bit longer to be ready.

BR

Given that the present tiff's need an extremely strong curve, what would the advantage be of making a DNG given that unless you can apply a specific gamma curve (not in ACR at any rate), the image will be far too dark to work with in the  raw converter? I'm very excited by the idea of a DNG output from this incredible program but only if the gamma can be programmed to show up in the raw converter so we can use it.
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Guillermo Luijk
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« Reply #272 on: December 09, 2008, 11:59:48 AM »
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Quote from: pom
Given that the present tiff's need an extremely strong curve, what would the advantage be of making a DNG given that unless you can apply a specific gamma curve (not in ACR at any rate), the image will be far too dark to work with in the  raw converter? I'm very excited by the idea of a DNG output from this incredible program but only if the gamma can be programmed to show up in the raw converter so we can use it.
The image will not be far too dark to work in the RAW converter. In fact in this example, the exposure control of ACR gives more exposure correction than you really need (in Perfect RAW we set an exposure correction of up to +8EV, truly usable with real 16-bit RAW files like the ones Zero Noise will produce).
I opened here the least exposed source RAW file, which will define the RAW exposure of the blend output, and managed to completely lift the shadows with a +4.0EV adjustment:




The advantage of a RAW output is that you can now feed it into your favourite development/tone mapping workflow based on RAW data (RAW developer, HDR program,...), while the TIFF output necessarily needed to go to Photoshop for tone mapping, and not everyone feels comfortable doing manual tone mapping.
This was a general complaint of some users who tried Zero Noise and felt lost to tone map such a dark image out of their preferred RAW developer (not my case BTW, I am fond of curves and with just two of them I can tone map most HDR images produced by Zero Noise, as explained in this tutorial (SP): Mapeo de tonos HDR).

Now the only difficult part is to deal with high dynamic range scenes and tone map them. But this is not a flaw of the method or concept of Zero Noise, which never was intended as a tone mapping tool, this is simply an issue that everyone will have to face when trying to fit HDR information on a LDR device (computer screen, printed paper,...).

BR
« Last Edit: December 10, 2008, 05:22:26 AM by GLuijk » Logged

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« Reply #273 on: December 09, 2008, 03:27:09 PM »
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Quote from: GLuijk
The program will take a bit longer to be ready.

Man, I can't wait!  Please let us know when it's ready    

John
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Guillermo Luijk
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« Reply #274 on: December 10, 2008, 09:11:41 AM »
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Man, I can't wait!  Please let us know when it's ready  
OK, I have been finally given the RAW file, please download it from: ZERO NOISE VIRTUAL RAW (English). Find the links to the original RAW files so as to the resulting virtual noiseless RAW after Fig. 9.

The result in DR is outstanding. Adjustments straight from ACR:



This comparision demonstrates that none of the original RAW files were able by themselves to capture all the dynamic range:

SHADOWS COMPARED TO RAW 1 (100% crops):


HIGHLIGHTS COMPARED TO RAW 1 (50% crops):




BR
« Last Edit: December 15, 2008, 08:18:05 AM by GLuijk » Logged

jsch
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« Reply #275 on: December 10, 2008, 09:46:09 AM »
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Hi Guillermo,

you are a genius. What can be done to assist you?

May I dream? PT-Lens and Zero Noise join there forces and produce a DNG with no/low noise and lens correction.

Thank you,
Johannes
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« Reply #276 on: December 10, 2008, 06:35:52 PM »
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Quote from: GLuijk
OK, I have been finally given the RAW file, please download it from: ZERO NOISE VIRTUAL RAW. Find the links to the original RAW files so as to the resulting virtual noiseless RAW under Fig. 9.
(English online translation available, icon left).

The result is outstanding.

I've played around with the virtual RAW DNG in ACR, and yes, the result IS outstanding.  This is a really big deal, at least for me, so you are to be commended for your time and generosity.  Now, I REALLY can't wait for the next version of ZERO NOISE!

John
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« Reply #277 on: December 11, 2008, 09:30:09 AM »
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Hey Guillermo,

You obviously have a strong understanding of digital imaging theory and application.  Given your impending release of ZERO NOISE VIRTUAL RAW, do you have any suggestions for tone mapping which will avoid the "HDR cartoon" look?   For example, when you open the virtual raw file that you have provided on your website, how do you go about making it aesthetically pleasing to your eye?  Would you be able to provide suggested tone mapping curves, perhaps in .xmp format (since camera raw/lightroom are popular), assuming a standard 4-stop gap between the source raw files?  If this is not feasible, then would you mind explaining the difficulties involved?

Thanks,
John
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Guillermo Luijk
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« Reply #278 on: December 11, 2008, 11:41:58 AM »
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Quote from: button
You obviously have a strong understanding of digital imaging theory and application.  Given your impending release of ZERO NOISE VIRTUAL RAW, do you have any suggestions for tone mapping which will avoid the "HDR cartoon" look?   For example, when you open the virtual raw file that you have provided on your website, how do you go about making it aesthetically pleasing to your eye?

So far (I mean in the future I can change my mind), the only way to obtain really pleasant natural looking HDR scenes is doing manual tone mapping because the software routines are not intelligent enough yet to emulate eye behaviour. Talking about existing software, the only quite close to this IMO is Enfuse, which produces quite pleasant results and is probably the simplest of all the algorithms around (it just scores pixels on each of the input image according to brightness, saturation and contrast, and that scoring is the weight for a not too complicated blending process). But still I prefer to do it by hand.

I think a really good HDR algorithm should first analyse the scene, and try to 'understand' it, identifying blocks or elements that humans see as a whole in terms of luminance. For instance inside a room with a window facing outside, all what is inside the frame of the window should be identified as a unique block, and should be processed as such. Another block could be the walls. Next block could be the floor which has tiles which are quite darker than the walls, and much darker than the window, and so forth,... In this way eye behaviour emulation would be much more realistic than present programs that hardly identify entire 'blocks' but adjust very precisely local contrast on small portions of the scene.

In this case I just did a quick developing in ACR (I never use it), keeping exposure at about -0.2 or close, and lifting the shadows strongly with Bright and with the curve. Later already in PS I applied a final contrast 'S' curve and that's it. But as I said it was a quick tone maping, I didn't intend to do it fine (among other things my laptop has a terrible uncalibrated screen).

In this Tutorial HDR I explain how I do it with just 2 curves:
1. Bright push up, with a blurred layer mask to protect the highlights.
2. Contrast 'S' curve.

These 2 curves have the property to be (sorry if this is not the proper English math term) monotonous rising. That means that with those curves you will never make some point A that was brighter than a given point B in the real scene, become less bright than B in the final image. This is something often happens in HDR software; sometimes you try to find out where the light was coming from, where the sun was, where the lamps, but global contrast is so flat and there is such absence of shades that you cannot.

BR
« Last Edit: December 11, 2008, 11:49:38 AM by GLuijk » Logged

Jonathan Wienke
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« Reply #279 on: December 20, 2008, 11:40:27 AM »
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Quote from: pom
Given that the present tiff's need an extremely strong curve, what would the advantage be of making a DNG given that unless you can apply a specific gamma curve (not in ACR at any rate), the image will be far too dark to work with in the  raw converter? I'm very excited by the idea of a DNG output from this incredible program but only if the gamma can be programmed to show up in the raw converter so we can use it.


When processed as DNG, you won't need to apply super-strong curves. You're looking at a file that is still linear--the RAW converter has not applied any gamma curve yet. The DNG will process just like any other RAW, but with more highlight detail and less shadow noise.

Overall, a very good effort so far. I look forward to making HDR DNG files...
« Last Edit: December 20, 2008, 11:49:49 AM by Jonathan Wienke » Logged

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