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 Post subject: RAW File noise ??
PostPosted: Sat Jun 30, 2012 1:38 am 
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Hi all

I have started to shoot photos in RAW (CR2) rather than jpeg however i got abnormal amount of noise especially on the dark colours

Extreme Example: I just took a shot of the moon and on the LCD everything looked fine, black was black and the moon was properly exposed

however when I view the CR2 on the computer to edit, everything went AWOL :shock: ... the black is now full of red, blue, purple (its like static on an analog TV)

and the moon just a white spot (waaay overexposed ,... )

Am I doing something wrong or is this just the way RAW files makes it.

and how would even begin editing this :?

Thanks for your reply :D


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 1:43 am 
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what camera? what raw file reader?

can't start answering your questions till we know..


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 1:45 am 
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canon xs

raw file reader - digikam


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 8:49 am 
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You are used to seeing processed jpeg files with some amount of noise reduction. When you start using raw files you get unprocessed data, so you always have do some processing yourself. The best way to ensure there is the least amount of noise in your photos is to use a good raw converter: canon's digital photo processor is a free alternative, which also uses your Jpeg presets to match your raw files to the screen preview. Another alternative is very powerful Adobe camera raw or Lightroom, but they aren't free.
If you are doing long exposures you can also minimize noise by turning on 'long exposure noise reduction' in your camera (if it has it)—this will help get rid of the noise in dark areas, but will double your exposure time.
This has worked for me extremely well when I am doing a minute or two long exposures.
If you are using high iso, you have to remove noise in one of the raw converters.


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 3:01 pm 
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I see.

i downloaded program called "rawstudio" since im using linux and the canon raw processor is not supported on the windows emulator

but anyway rawstudio worked good and I was able to adjust few settings before saving it as jpeg

so im getting the idea that RAW format allows the photographer to fine tune the exposure, WB , Hue, sharpness etc rather than letting the limited processing power of the camera to guess?


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 4:00 pm 
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Precisely


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 5:54 pm 
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Maybe even more important is the ability to reprocess a raw image over again in different ways when you become more knowledgeable about what you and with more advanced tools when they come available.


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 Post subject: Re: RAW File noise ??
PostPosted: Sat Jun 30, 2012 6:50 pm 
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Metrix wrote:
Maybe even more important is the ability to reprocess a raw image over again in different ways when you become more knowledgeable about what you and with more advanced tools when they come available.


yeah, so don't delete your files right away :)


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 Post subject: Re: RAW File noise ??
PostPosted: Tue Jul 03, 2012 9:44 am 
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I recently shot RAWs with my GF2 and used RawTherapee (freeware) to process them. I am no expert in processing RAWs and I do find there are noise in my converted photos as well even though most of my photos are ISO200 outdoor pictures. I am sure there are ways to reduce the noise but I just haven't had the chance to play with it yet.

I didn't really care since I was doing B&W street photography and I rather like the bit of noise in the B&Ws anyway.


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 04, 2012 1:22 pm 
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Since the RAW format is very flexible, that means i can create multiple exposures of a photo and blend them to create HDR.

So why would photographers do multiple exposures from a tripod?

Are the two methods interchangeable?

Thanks


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 04, 2012 1:40 pm 
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1000volta wrote:
Since the RAW format is very flexible, that means i can create multiple exposures of a photo and blend them to create HDR.

So why would photographers do multiple exposures from a tripod?

Are the two methods interchangeable?

Thanks


Dynamic range of multiple exposures >> dynamic range of 1 exposure.

This still remains true even if you shoot RAW. A single RAW image may still have blown highlights or detailless shadows. So no, not interchangeable. An HDR from a single shot would generally only yield the results you're after if the RAW image contains details in the highlights and shadows (but may not be visible on-screen).


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 04, 2012 1:57 pm 
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the main difference between multiple exposure HDR and one exposure tweaked Raw files combined to HDR is the amount of artifacts and noise in your final image. While you can generally bring back all the details in the dynamic range of a raw file (provided you used proper capture technique) you can only do so much with noise reduction that having good looking HDR in the end is tough. Using true 32bit HDR process without tonemapping will give you the dynamic range you're after without the crazy overdone look of what most HDamateuRs achieve. Depends on what you're after.


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 11, 2012 1:10 am 
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Hey, I like tonemapping. Of course, many people overdo it. Check out Trey Parker (stuckincustoms.com) for sensible tonemapping (one of his is hanging in the Smithsonian in Washington DC).

But what everyone else said about RAW and all that is correct. If the moon is grossly overexposed, it might simply be a problem with your raw processor program, since the RAW file isn't inherently holding that much different data than the JPEG file.


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 11, 2012 11:02 am 
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Ugh, Trey. Overrated and STILL overdone HDR. Though to be fair I haven't looked at his work in at least a year.


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 11, 2012 11:26 am 
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Eric wrote:
Hey, I like tonemapping. Of course, many people overdo it. Check out Trey Parker (stuckincustoms.com) for sensible tonemapping (one of his is hanging in the Smithsonian in Washington DC).

But what everyone else said about RAW and all that is correct. If the moon is grossly overexposed, it might simply be a problem with your raw processor program, since the RAW file isn't inherently holding that much different data than the JPEG file.


I'd say an extra few stops worth of data is certainly quite a bit different than a JPG.


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 11, 2012 11:30 am 
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Oh wow, yeah. I stopped reading at the Trey Parker bit... oops. RAW has considerably more data than jpeg. Exponentially.


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 Post subject: Re: RAW File noise ??
PostPosted: Tue Jul 17, 2012 4:51 pm 
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ions wrote:
Oh wow, yeah. I stopped reading at the Trey Parker bit... oops. RAW has considerably more data than jpeg. Exponentially.


Realistically, the ADC in the sensor is a 14-bit output and the camera essentially tone-maps them into an 8-bit JPG, depending on the "vibrance" settings. So, yes there is some additional information, but it's not so drastically different that it would cause one to be perfectly exposed, and the other to be "completely blown out" as was stated earlier.

More information, but not substantially different information, is all I was saying.


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 Post subject: Re: RAW File noise ??
PostPosted: Tue Jul 17, 2012 5:39 pm 
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Assuming low enough ISO that the bits are not noise then 14 bits versus 8 bits is 64 times the number of levels that is considerably more.


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 18, 2012 2:48 am 
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Considerably finer resolution, but still capturing the same thing and quite possible to tone-map to a comparable . That's the idea of a proper tone-mapping anyway. :-) Still, it's all semantics. The point being, again in the context of this thread, extremely obvious purple splotches and a 3 stop overexposure in photo produced directly from a camera RAW (but working fine in a JPEG) doesn't have anything to do with the ADC resolution of the file, since they contain the same basic information (with a different tone mapping and resolution, obviously).


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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 18, 2012 9:13 am 
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I find it's interesting that your terminology seems to equates Raw processing and HDR processing with tone mapping. I agree as in original imaging processing terms a DSLR is a HDR device. But back in 2005 before Lightroom and when both RAW processing and HDR as we know it were in early stages of development there was a reluctance in the world of photography to see it this way. This is changing a bit but is still wrongly consider a separate process.

Back to the OP. In camera JPG is automatic tone mapping of the camera HDR image (the digital capture) into an 8 bit image. The camera processing does this with full knowledge of the camera's noise properties and dynamic range. It does this in the best way without knowing the intent of the photographer. In fact there is a mistaken thought that RAW images are in fact straight out of the sensor. Part of the high ISO ability of new cameras even when shooting RAW are actually algorithmic digital processing done in camera.

Now when it comes to RAW processing algorithms not all programs are created equal, If you take the program that came with the camera it should be able to create with the push of the button the same JPEG you saw in camera. From there it's up to the photographer to adjust his or her image to show their intent or in anyway that they desire.

If the Raw processing program did not come with the camera then the default setting will not usually produce the same jpeg as the in camera jpeg. Better RAW converters can produce vastly superior outputs to those of less advanced converters. Must convertors with the "wrong" tweaking can also give the look and feel of an "over cooked" HDR.

Now take the moon shoot. The moon because it is illuminated by the sun is approcimately as bright as a sunny noon day sidewalk. No consumer digital camera without using HDR multiple exposures has the dynamic range (about 17 stops) accept may be TMAX 400 film which can actually cover the range of the moon to the background night scene.

The RAW converter you used rendered the scene incorrectly by applying a tone curve which blow out the moon highlights and expanded the dark to the point that you were just seeing noise. Instead of being sensitive to the narrow histogram peak in the highlights it calculated incorrectly both the upper and the lower white and black points. I'm sure even with that RAW converter you used you could adjust the curves enough to bring it back into check.

It takes time and experience to learn to process RAW files in a way which can meet and exceed the camera jpeg output. It's all part of the craft of photography.




Eric wrote:
Considerably finer resolution, but still capturing the same thing and quite possible to tone-map to a comparable . That's the idea of a proper tone-mapping anyway. :-) Still, it's all semantics. The point being, again in the context of this thread, extremely obvious purple splotches and a 3 stop overexposure in photo produced directly from a camera RAW (but working fine in a JPEG) doesn't have anything to do with the ADC resolution of the file, since they contain the same basic information (with a different tone mapping and resolution, obviously).


Last edited by Metrix on Wed Jul 18, 2012 11:32 am, edited 2 times in total.

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 Post subject: Re: RAW File noise ??
PostPosted: Wed Jul 18, 2012 10:49 am 
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Eric wrote:
Considerably finer resolution, but still capturing the same thing and quite possible to tone-map to a comparable . That's the idea of a proper tone-mapping anyway. :-) Still, it's all semantics. The point being, again in the context of this thread, extremely obvious purple splotches and a 3 stop overexposure in photo produced directly from a camera RAW (but working fine in a JPEG) doesn't have anything to do with the ADC resolution of the file, since they contain the same basic information (with a different tone mapping and resolution, obviously).


At the end of the day, there's simply no getting around the huge difference in dynamic range captured in RAW vs JPG (and ultimately, the detail). Take any scene with a good variance in dynamic range and compare the detail of the RAW image vs. that of a JPG, especially in highlights as well as shadows.


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