http://www.eoshd.com/2016/09/now-available-eoshd-picture-profiles-brings-c-log-canon-dslrs-including-1d-x-mark-ii-5d-mark-iv/
EOSHD Creates "C-LOG" profile for Canon Cameras. Available for download
- Thread starter PureClassA
- Start date
Haha.
Canon Log is an algorithm designed by Canon, that squeezes the dynanic range of the RAW sensor output into the video image before compression and image formation, giving a flat looking file (because the highlights are lowered and shadows are highered).
What EOSHD so called C-log is, is a picture style applied after the compression and dynamic range has already been set to the exact same number as Neutral -4 Contrast.
EOSHD C-LOG is a joke, a low contrast picture style made by Canon picture style editor software.
Calling it C-Log is laughable.
I do however encourage it and encourage designing picture styles, just not claiming it's real LOG in anyway,
Canon Log is an algorithm designed by Canon, that squeezes the dynanic range of the RAW sensor output into the video image before compression and image formation, giving a flat looking file (because the highlights are lowered and shadows are highered).
What EOSHD so called C-log is, is a picture style applied after the compression and dynamic range has already been set to the exact same number as Neutral -4 Contrast.
EOSHD C-LOG is a joke, a low contrast picture style made by Canon picture style editor software.
Calling it C-Log is laughable.
I do however encourage it and encourage designing picture styles, just not claiming it's real LOG in anyway,
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By the way a MUCH more reliable and trustworthy is Technicolour Cinestyle. It's designed by Canon in colaboration with the world's most acclaimed colour science company. It's MADE BY CANON. So I'd much rather use that.
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John2016 said:
A color profile is not a C-LOG!!!
No, a C-Log is a colour profile.
Making a flat profile does not increase your dynamic range.
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privatebydesign said:John2016 said:
A color profile is not a C-LOG!!!
No, a C-Log is a colour profile.
Making a flat profile does not increase your dynamic range.
REAL C-LOG can prevent highlights and shadows from clipping.
Canon log (C-log) gamma profile preserves the most color and luminance data from the sensor.
"This Log curve offers more dynamic range then the original S-Log curve"
http://blog.abelcine.com/2013/01/18/sonys-s-log2-and-dynamic-range-percentages/
As David Mullen (ASC) explained:
"Those extra stops are what the sensor is able to capture.
Think of it this way, if the sensor, the recording, and the display device are all linear, no gamma curves applied, and the sensor can capture 14 stops and the display can show 11 stops, then is it better if the recording has 14 stops in it or 11 stops in it? What's the point of three more stops of information if you can't display it? Well, one advantage is that you can apply gamma curves, power windows, luminance keys, and knee and shadow compression to allow bright highlight detail and dark shadow detail outside of the display device's range to burn off to white (clip) or fall off into black more gradually while leaving the midtones with a more linear response to light.
There has always been some concern about recording log gamma in 8-bit codecs, if you try and cram too many stops of luminance into 8-bit, you may get banding artifacts on gradients. Now in reality it hasn't been as bad as some people thought, plus the advantages of having more stops of information seem to outweigh the banding issues, but it is still an issue until you move up to 10-bit."
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John2016 said:
Yes and none of that adds any dynamic range. No Log does, it is just a different way of sampling the same data coming off the sensor. Log's do not and cannot add native dynamic range off the sensor.
So what's the detailed difference between a 'normal' capture and a Log capture? The distribution of tonal sampling. The high and low are the same, so the full DR range is contained within whatever method is used to store the data, but in a Log profile the capture data has a logarithmic curve applied to the sample spacing, meaning compared to the sensor linear output and normal raw files, the number of highlight tones is sacrificed in favor of more shadow tones. This helps shadow lifting capability, but does not 'add' dynamic range, meanwhile the reduction in the number of brighter tonal values has been shown to be not visible to the human eye in moving image scenarios.
The follow on comment would be what would be the difference in capabilities in post production between true Log files and a 'Log profile'? In theory the only difference would be the ability to lift shadows, a Log file will lift shadows better though there will still be noise, however if you use an ETTR technique with a 'normal' video capture and lower exposure in post the results will be practically identical.
To be clear, both 'normal' video and Log video use the same output information off the sensor, which is without exception linear.
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privatebydesign said:
WOW, I wish there were more posts like this. In one minute I have learned more than one hour muddling through posts that use jargon I'm not familiar with and lose me. I "feel" like I'm now twice as smart! 8) Of course, I already understand logs from my engineering and should have put 2+2 together - duh. ??? It reminds me of the day long ago when I was wondering what IQ was - double duh, but when you're new to a topic it's overwhelming. So maybe more of the hotshots should keep us poor floundering morons in mind and have compassion! ;D
Jack
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"prevent highlights and shadows from clipping" - if I'm catching on, highlights get clipped while shadows get lost in noise. Right? The above was just a casual way of saying that I think.
Jack
Jack
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Jack Douglas said:
Sort of. If you're compressing the luma values into a 0-255 8-bit range, using a contrasty picture style (e.g. Canon Standard) often you end up with a lot of stuff at 0 and 255, and unlike your 14-bit RAW images which have over 16K different values, there is no way you are ever going to extract any detail from a load of data where every pixel has a luma value of 255.
So it's best to use profiles which protect your highlights and shadows, although the benefits of LOG images in an 8-bit space have to weighed again crushing all the data into such a small range of values. If you dont have a a high DR scene in front of you, shooting LOG and compressing your luma range from 0-255 to 50-200 is likely to hurt more than help, and is likely to introduce noise and banding into your image. And unless you have a external monitor with a viewing LUT installed you dont know what your LOG image will look like, which can make properly judging exposure much harder with LOG. And you really need to get your exposure right with LOG, so it's not something I recommend to students who're just starting out.
If you want to know about C-Log, then Canon have a really good white paper on it here which might dovetail nicely with your engineering background http://learn.usa.canon.com/app/pdfs/white_papers/White_Paper_Clog_optoelectronic.pdf
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syder said:
Thanks Syder. I'm overloading with a ton of new info but slowly catching on, I think. :-\
So this is more about compression than about a noise floor issue. I'll read the article shortly.
Now I must remind myself that I need to cool it and learn over days not hours.
Jack
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OK, I read it, well glossed it actually, and that's all I needed. It all makes sense and the detail of it really doesn't matter to me but it's nice to know where the terms originated and understand, for example, that each sensor will have its particular transfer function and the conversion from photons impinging on pixels to electrical signal to digital encoding will be unique to the sensor and then Canon, in this case, must determine how this linear raw data ultimately is used to represent the values that are to be output. That is done by using a table of values (LUT) that is representative of a nonlinear (logarithmic) function so that the compressed information best represents the original uncompressed information...... I think :-\
I better just stick to shooting.
Jack
I better just stick to shooting.
Jack
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You made me laugh!Jack Douglas said:OK, I read it, well glossed it actually, and that's all I needed. It all makes sense and the detail of it really doesn't matter to me but it's nice to know where the terms originated and understand, for example, that each sensor will have its particular transfer function and the conversion from photons impinging on pixels to electrical signal to digital encoding will be unique to the sensor and then Canon, in this case, must determine how this linear raw data ultimately is used to represent the values that are to be output. That is done by using a table of values (LUT) that is representative of a nonlinear (logarithmic) function so that the compressed information best represents the original uncompressed information...... I think :-\
I better just stick to shooting.
Jack
That's why I don't spend too much time in theory.
I read what people say or write, I go out to prove then practice it.
From what Syder said the most important piece of info for me is "And unless you have a external monitor with a viewing LUT installed you dont know what your LOG image will look like, which can make properly judging exposure much harder with LOG. And you really need to get your exposure right with LOG" -
And that is exactly how I do mine. I use a ninja assassin (additional cost and weight) but you see your exposure and RGB curves live, you add your LUT so you know what it is doing (although I reduce it to around 85% in post so I am safer) and you have prores HQ right on a hard-drive (no transcoding needed). I record only small chunks of 4K footage on the Cfast for crop and small panning as B roll.
Of all complaints about the 1DX II the only one that hurts me seriously is the lack of 4K through HDMI. It would have made it my perfect dream gear.
I tried the EOSHD log and LUT but I don't see much advantage for what I am doing. For the price I paid though, I do not complain.
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Besisika, I can see that I don't really have a very clear idea about what is going on - just some bits and pieces are starting to make a little sense. If I was looking over your shoulder it would help immensely.
If you or others would be willing, what I really need right now is very specific setup guidance in making menu choices for video. Anything I do will be outdoor nature related around my acreage home for now. I don't have city type subject matter to practice on but if a moose wanders through my yard I'd sure like a minute or two of that, etc.
Jack
If you or others would be willing, what I really need right now is very specific setup guidance in making menu choices for video. Anything I do will be outdoor nature related around my acreage home for now. I don't have city type subject matter to practice on but if a moose wanders through my yard I'd sure like a minute or two of that, etc.
Jack
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I am not an outdoor shooter, I shoot indoor, but if you asked me to shoot animals wandering by I would use a monopod for mobility, I would use my 100-400 II at 5.6. If the sun is bright I would use an ND filter to knock 3 stops down; which will take me to 1/60thsec, f5.6, ISO 50. If it is dark then I would move to ISO 100 (rule of F16). If it is late in the afternoon then I might not need ND at all.Jack Douglas said:
The background is the key; if it is some trees then its exposure is the same as my subject so the dynamic range is not requiring any additional stuff, just shoot. If the background is the sky, and it is blue: you should be ok with or without a profile (c-log or cinestyle) bu I would use one to make sure. If the background is the sky and it is overcast then you might end up with white sky. Simply choose your spot well, to avoid overcast sky or anything white.
I would shoot at 30fps on 4K (I would avoid 24fps for now until they fix the rolling shutter on it) to preserve space on the C-fast, you could use as well, if you have, good CF card (which I do). If you have a bunch of Cfast card then I would go to 4K 60fps.
In post, use a LUT, I reduce it to 60-85% to taste. As for 4K you will need to transcode it before playing with it and work with smaller files.
If you don't want to use LUT then you will have to find a dark background during shooting to avoid the sky and shoot with Standard or neutral profile (you might need to reduce sharpness and contrast). If you don't want to do much in post, then don't shoot in 4K yet, just shoot 1080p at 60fps.
I use an external recorder because I shoot events indoor, like singing choir or medal ceremony during sport events and I need to shoot continually for 10-15min. I use the C-fast for some short scenes so I could use it to zoom into the subject closer (4k is twice the size - roughly), or pan a little to create some movement now and then.
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Thanks again Besisika but I must say in honesty there are things you say that I still need to get more background information on but at least I'm getting the bigger picture much better now. It'll come.
You're doing very well with, as I understand it, English as a second language so this is just a "fun" comment. We say "we get the hang of it" or we have "caught on", when we understand something.
Jack
You're doing very well with, as I understand it, English as a second language so this is just a "fun" comment. We say "we get the hang of it" or we have "caught on", when we understand something.
Jack
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Actually, English is my 4th language and I mix up terminology/expression sometime and people don't get what I am saying.Jack Douglas said:Thanks again Besisika but I must say in honesty there are things you say that I still need to get more background information on but at least I'm getting the bigger picture much better now. It'll come.
You're doing very well with, as I understand it, English as a second language so this is just a "fun" comment. We say "we get the hang of it" or we have "caught on", when we understand something.
Jack
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Besisika said:Actually, English is my 4th language and I mix up terminology/expression sometime and people don't get what I am saying.Jack Douglas said:Thanks again Besisika but I must say in honesty there are things you say that I still need to get more background information on but at least I'm getting the bigger picture much better now. It'll come.
You're doing very well with, as I understand it, English as a second language so this is just a "fun" comment. We say "we get the hang of it" or we have "caught on", when we understand something.
Jack
WOW, you do very well. In our house my wife insisted the kids get English and French via immersion and they now have some Spanish and German. Me, I'm English only, raised by a father who was always bashing the perceived "French" Quebec perspective that he'd hear daily on the news (he hated Pierre Trudeau
). We lived in the west of course. He wasn't bigoted but had some resentments over WWII and Quebec.Fortunately, essentially no one on CR cares about English and spelling but camera brand sure pushes buttons.
Jack
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