Noise - Underexposure or Skill or my 7D or something else

Daniel - thanks for promptly responding. It would take me some time to grasp all you have posted in that thread and especially to relate various adjectives (although funny but English not being my first language, you probably have any idea what I mean) to real world shooting experience. All that aside, should my takeaway from that thread be this statement of yours:

"For Canon, how I would put it is this: ETTR then ITTR (ISO to the right), avoid the +1/3 ISO (125, 250, 500, etc.), but the -1/3 ISO (160, 320, etc.) are fine and don't go over 1600 (on most Canons) -- use negative EC instead."

Yes, that's about the briefest summation I can come up with.

That gives me something actionable to expand upon and apply the rest of what's mentioned there in practice!!

Daniel mentioned something that I had discovered a couple years ago after getting my 7D and shooting at high ISO. Under certain types of lighting such as incandescent and late evening outdoor shots, the amount of light at the blue end of the spectrum is much less than it is towards the red end of the spectrum. If you take a noisy photo shot under those conditions, you can see the effect of noise changing by tweaking the color temperature and bias adjustments in the basic panel of ACR/LR. If you want to see how noisy each color channel is, go to the channels tab and turn on only the channel of interest. This will work better if you set the channels to display grayscale because blue generally looks very dark when viewed in color.

If the noise is primarily in one channel, you can apply NR to that channel only without seriously impacting the overall sharpness and color quality of the image. A few tools that you can use are Filter>Noise>Despeckle, Filter>Noise>Reduce Noise, and Filter>Blur>Surface Blur. The latter works best on large smooth surfaces such as the sky while Despeckle works well on details.

There is some "cross pollination" of noise between channels during the demosaicing process because the camera uses an intermediate YCrCb color model where it takes the difference between adjacent green-red and green-blue photodiode sites as well as a weighted average luminance value. In the end each individual monochrome photodiode on the sensor becomes a component of of four adjacent image pixels. This blending tends to smooth out some of the "noise" of individual photodiodes. It is also partially responsible for the slight reduction in sharpness which capture sharpening is aimed at correcting.

nikmar08 wrote in post #13248512
Thanks for more people chiming in and adding to my confusion I'm still ruminating on the thoughts expressed earlier, and boy, now I have to deal with fitting in more aspects of noise into the equation!! Never hurts to know more, eh?

kfreels - while I do see some noise in your shot but not too much. I have some observations / questions though:
1. I see you shot it at 17mm f/3.2 with a SS of 1/640 and at ISO 200 and there's almost 2 stops of headroom on the right of the histogram. Was that deliberate because you wanted to specifically test noise in the context of color channel and white balance aspects that Daniel introduced in this thread? Or was it because you took it in the same hurried way as I took my shot - it's just that my settings were worse, 1/1000s, f/9 and such and it is natural to goof up?

2. Would you agree that even your shot looks a bit soft like mine? Even if not, what did you lock focus on and what portion of the frame did you meter off of?

Actually I tool several shots at various settings trying to do my best to pick up noise on the rainbow. It was a nice rainbow, but there isn't a decent place in my neighborhood to get a pleasing composition so I figured I would spend that brief period of time playing and to see if I could reproduce your noise using auto settings. This one had the most noise in the cloud area of all of them. ISO 200 is my "default" ISO that I leave the camera on so I never changed that. But I did try several different exposure combinations in AV mode metering off of the foreground and the background. In a real setting I would have been selective with my metering - perhaps on a tree trunk or something else fairly neutral in the midtones and focused on the trees in the foreground but I assumed you were generally using evaluative or center weighted metering so I used center weighted and let the camera do its thing. You're right. For this discussion I should have taken a few shots tot he right but I really didn't think of it. I guess I'll just have to catch the next rainbow.

The shot you see here is soft because I focused and metered on the rainbow itself. At 3.2 that left the foreground soft. Here's another where I focused on the foreground and a bit less exposure.

http://dl.dropbox.com/​u/44688334/_MG_2709.CR​2

Bill Boehme wrote in post #13249069
Daniel mentioned something that I had discovered a couple years ago after getting my 7D and shooting at high ISO. Under certain types of lighting such as incandescent and late evening outdoor shots, the amount of light at the blue end of the spectrum is much less than it is towards the red end of the spectrum. If you take a noisy photo shot under those conditions, you can see the effect of noise changing by tweaking the color temperature and bias adjustments in the basic panel of ACR/LR. If you want to see how noisy each color channel is, go to the channels tab and turn on only the channel of interest. This will work better if you set the channels to display grayscale because blue generally looks very dark when viewed in color.

If the noise is primarily in one channel, you can apply NR to that channel only without seriously impacting the overall sharpness and color quality of the image. A few tools that you can use are Filter>Noise>Despeckle, Filter>Noise>Reduce Noise, and Filter>Blur>Surface Blur. The latter works best on large smooth surfaces such as the sky while Despeckle works well on details.

There is some "cross pollination" of noise between channels during the demosaicing process because the camera uses an intermediate YCrCb color model where it takes the difference between adjacent green-red and green-blue photodiode sites as well as a weighted average luminance value. In the end each individual monochrome photodiode on the sensor becomes a component of of four adjacent image pixels. This blending tends to smooth out some of the "noise" of individual photodiodes. It is also partially responsible for the slight reduction in sharpness which capture sharpening is aimed at correcting.

This is exactly what I do with my 7D and 1D4 action sets I developed. I selectively run filters on each color channel.

TeamSpeed wrote in post #13249677
This is exactly what I do with my 7D and 1D4 action sets I developed. I selectively run filters on each color channel.

How to you open each channel inside of light room and only apply NR to that specific channel. There are no channels that I can find in LR. Am I missing something? I know how to edit an image in Lightproof (edit as a smart object), then in PS D-click the little icon on the layer and it opens in ACR.

I use LAB mode( in PS) so I am familiar with channels, I just do not see them in Light-room. A link to a tutorial would be awesome. Thanks

akfreak wrote in post #13253166
How to you open each channel inside of light room and only apply NR to that specific channel. There are no channels that I can find in LR. Am I missing something? I know how to edit an image in Lightproof (edit as a smart object), then in PS D-click the little icon on the layer and it opens in ACR.

I use LAB mode( in PS) so I am familiar with channels, I just do not see them in Light-room. A link to a tutorial would be awesome. Thanks

There's no per-channel noise reduction in LR.

Stone 13 wrote in post #13253285
There's no per-channel noise reduction in LR.

What a bummer. When I wrote my previous post, I just presumed that LR could do most of the stuff in ACR and PS based on what LR users say about the program. It sounds to me like LR is more like PSE with a better raw converter. OK, the answer is ... get PS. I actually use the Enhanced version because of the statistical analysis tools and ability to work with Matlab for complex signal processing.

I am using cs3 and noiseware, along with some built-in cs3 filters in these actions. I have lr3, I just don't use it but probably should.

Bill Boehme wrote in post #13253314
What a bummer. When I wrote my previous post, I just presumed that LR could do most of the stuff in ACR and PS based on what LR users say about the program. It sounds to me like LR is more like PSE with a better raw converter. OK, the answer is ... get PS. I actually use the Enhanced version because of the statistical analysis tools and ability to work with Matlab for complex signal processing.

Ah, no, LR has the ACR Raw "engine", but nothing from PS. The only other thing it has in common with PS/PSE is some very good organizational tools.

The reason so many people love it is that integrates so much of our "normal" workflow so well and efficiently. But if you are used to working in Camera Raw and then opening in the PS editor for "special" tasks, well, that hasn't changed with Lightroom. You have the same Raw tools, but you'll need Photoshop for the more advanced stuff, like the channel editing that is being discussed.

'Course Lightroom and ACR both let you do work on color channels in the HSL section, but it's working with colors, not things like NR.

tonylong wrote in post #13255954
Ah, no, LR has the ACR Raw "engine", but nothing from PS. The only other thing it has in common with PS/PSE is some very good organizational tools.

The reason so many people love it is that integrates so much of our "normal" workflow so well and efficiently. But if you are used to working in Camera Raw and then opening in the PS editor for "special" tasks, well, that hasn't changed with Lightroom. You have the same Raw tools, but you'll need Photoshop for the more advanced stuff, like the channel editing that is being discussed.

'Course Lightroom and ACR both let you do work on color channels in the HSL section, but it's working with colors, not things like NR.

OK then where can you apply NR to separate channels in ACR. I think you are in PS and using a plugin when working in the channels menu of an image in PS not ACR . I have never seen a way to apply noise reduction locally without being in PS, then you need a plugin.

I wish they would make a NR adjustment brush for LR. NR in LR and ACR are global, It would be nice to selective apply it.

What I do is apply it to an image in various states in LR, export as a smart object to PS and use layer masks to apply NR to specific areas (local adjustment). Lots of time to achieve selective adjustment of NR.

Right, like I said, you can't do that in either ACR or LR. It's a Photoshop editor thing.

akfreak wrote in post #13256031
OK then where can you apply NR to separate channels in ACR. I think you are in PS and using a plugin when working in the channels menu of an image in PS not ACR . I have never seen a way to apply noise reduction locally without being in PS, then you need a plugin.

I wish they would make a NR adjustment brush for LR. NR in LR and ACR are global, It would be nice to selective apply it.

What I do is apply it to an image in various states in LR, export as a smart object to PS and use layer masks to apply NR to specific areas (local adjustment). Lots of time to achieve selective adjustment of NR.

tonylong wrote in post #13256074
Right, like I said, you can't do that in either ACR or LR. It's a Photoshop editor thing.

Yep, and it is not a plug-in, it is a palette. Normally, you work in the layers palette, but if you switch to the channels palette, you can selectively turn color channels on or off. The typical use is to look at a single channel.

The reason that NR is global is that ACR/LR is for capture sharpening. Basically, ACR/LR are for capture processing, but the Adobe raw converter is beginning to take on a life of its own and we could even think of PS becoming a plug-in to ACR/LR. With the advent of the adjustment brush we almost have the equivalent of working in layers, but it still does not have selective NR.

akfreak wrote in post #13256031
I wish they would make a NR adjustment brush for LR. NR in LR and ACR are global, It would be nice to selective apply it.

You can make a brush with a de-sharpen setting and reduced clarity and then paint that over backgrounds and OOF areas. Obviously that might not work well for your subject, depending what it is, but that's the basis for the skin softening preset.

It always helps to tweak the sharpening mask before making any other attempt to reduce noise.