Mikhail Bogdanov
Veteran Member
And he is "not" way too often.
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"Beware of the histogram display. It stinks."
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MMuddler
Veteran Member
Rockwell's claim is that the histogram only represents green channel information. What in fact is the truth?
If the histogram actually looks at all channels, how much of the total response comes from the green channel?
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Marabou Muddler
Iliah Borg
Forum Pro
Histogram is calculated same way as composite histogram in PS, summing weighted RGB channels. Nearly 60% is green channel
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no text
As usual, Ken blows things out of proportion.
The histogram measures luminance, which is technically around 60% green photosites. Therefore AT BEST, Ken's statement shows a 40% margin of error. The histogram is very useful if you know how to use it and understand it's limitations.
However, one thing always seems to get left out in histogram/luminance discussions. Everyone assumes that the luminance is calculated as the sum of the photosites. But is this assumption true? Perhaps it is a simple sum of the color channels, but it's not out of the question to consider that Nikon may have programmed some color channel compensation into the equation. In fact, to do this correctly, it would have to also consider WB since this affects the overall temperature of the image. I would not be surprised if this were the case.
I would love to hear from someone who has technical knowledge on this.
The histogram measures luminance, which is technically around 60% green photosites. Therefore AT BEST, Ken's statement shows a 40% margin of error. The histogram is very useful if you know how to use it and understand it's limitations.
However, one thing always seems to get left out in histogram/luminance discussions. Everyone assumes that the luminance is calculated as the sum of the photosites. But is this assumption true? Perhaps it is a simple sum of the color channels, but it's not out of the question to consider that Nikon may have programmed some color channel compensation into the equation. In fact, to do this correctly, it would have to also consider WB since this affects the overall temperature of the image. I would not be surprised if this were the case.
I would love to hear from someone who has technical knowledge on this.
muskiemouth
Senior Member
Rockwell is the "Ralph Wiggum" of photography.
anotherMike
Forum Pro
I might (totally) rephrase your quote with "Beware of anything Ken Rockwell writes, and take it with a large grain of salt"
He tends to be reactionary and is very, very opinionated, often jumping to some conclusion that often has some partial truth, but is not particularly well thought out. Thus he tends to alarm rather than inform. Honestly, I don't bother reading his stuff that much, I'd rather read what Hogan or Reznick have to say (or Yves or Iliah on this board), but to each his own.
Yes, he's partially correct in that the histogram does not show each of the channels, something I wish it had the option to do. But in terms of stinking, no, the histogram is potentially the most useful tool for getting your exposure correct ---> but with a little bit of input from your brain too.
Basically, since the histogram is looking at a rough representation of luminosity, we (as in our brain) need to evaluate the scene a bit. If there are any bright, fully saturated colors (bright red shirts, strong light blue blouses, bright yellow dresses, for example), then we have to think "hmm, possible blown channel" and back off a bit from pushing the histogram to the right edge since those strong colors may not show in the histogram. It takes some practice, but it's not rocket science. Plus you can always do what we slide shooters often did, do a quick 1/3 stop bracket around where you think you need to be.
Getting digital exposure right is harder than lazily slapping some color neg film in your film camera and being "close enough". If you underexpose you're going to get noisy quick, and if you torch the channels, you're done. The histogram, and the highlight indicator, along with some thinking, are all equal components to getting it as close as we can.
-m
He tends to be reactionary and is very, very opinionated, often jumping to some conclusion that often has some partial truth, but is not particularly well thought out. Thus he tends to alarm rather than inform. Honestly, I don't bother reading his stuff that much, I'd rather read what Hogan or Reznick have to say (or Yves or Iliah on this board), but to each his own.
Yes, he's partially correct in that the histogram does not show each of the channels, something I wish it had the option to do. But in terms of stinking, no, the histogram is potentially the most useful tool for getting your exposure correct ---> but with a little bit of input from your brain too.
Basically, since the histogram is looking at a rough representation of luminosity, we (as in our brain) need to evaluate the scene a bit. If there are any bright, fully saturated colors (bright red shirts, strong light blue blouses, bright yellow dresses, for example), then we have to think "hmm, possible blown channel" and back off a bit from pushing the histogram to the right edge since those strong colors may not show in the histogram. It takes some practice, but it's not rocket science. Plus you can always do what we slide shooters often did, do a quick 1/3 stop bracket around where you think you need to be.
Getting digital exposure right is harder than lazily slapping some color neg film in your film camera and being "close enough". If you underexpose you're going to get noisy quick, and if you torch the channels, you're done. The histogram, and the highlight indicator, along with some thinking, are all equal components to getting it as close as we can.
-m
In fact, Ken praises the camera a lot! He even rates it at par with the D2H in terms of image quality. This histogram thing is the only niggle that seems to bother him a lot.
If this is how it is in other DSLRs (of other brands, I mean), then no worries for me.
Even in the case it is found only in Nikon DSLRs, I think you guys has made it less alrming for me! Thanks!
If this is how it is in other DSLRs (of other brands, I mean), then no worries for me.
Even in the case it is found only in Nikon DSLRs, I think you guys has made it less alrming for me! Thanks!
Mikhail Bogdanov
Veteran Member
That's unpossible.
Mikhail Bogdanov
Veteran Member
John Crellin
Forum Enthusiast
Histogram under Gloassry on this site is pretty good.
But really it's pretty simple to get quite a lot out of a histogram like the D70 one:
If you see a mountain range with the footlhills all showing on both sides - right down to nothing then you have hit one of those scenes the D70 can fit every level in and no problem.
If the plot cuts off at the right hand end - or worse has a big peak there hard up against the edge then you have lost highlights and need to consider whether that matters - might be sky (and you are no bothered) - look at the highlights frame.
If it cuts off at the bottom you have lost some detail down in the shadows and will get black for parts of the picture - no D70 frame to show you where this is (unless I missed something !)
As a secondary function, if there is space above the plot with nothing in it then the D70 has underexposed and, if you don't want to post-process, then try again with more exposure. But in my experience this only happens when the range of the scene is low and you haven't actually lost anything but you will get the famous D70 dull picture without post - processing !
Those are the things I mainly use it for - any others ?
But really it's pretty simple to get quite a lot out of a histogram like the D70 one:
If you see a mountain range with the footlhills all showing on both sides - right down to nothing then you have hit one of those scenes the D70 can fit every level in and no problem.
If the plot cuts off at the right hand end - or worse has a big peak there hard up against the edge then you have lost highlights and need to consider whether that matters - might be sky (and you are no bothered) - look at the highlights frame.
If it cuts off at the bottom you have lost some detail down in the shadows and will get black for parts of the picture - no D70 frame to show you where this is (unless I missed something !)
As a secondary function, if there is space above the plot with nothing in it then the D70 has underexposed and, if you don't want to post-process, then try again with more exposure. But in my experience this only happens when the range of the scene is low and you haven't actually lost anything but you will get the famous D70 dull picture without post - processing !
Those are the things I mainly use it for - any others ?
Michael Kempf
Senior Member
IMO the purpose of the histogram is more oriented towards helping you pick up a better exposure so as to maximize the use of available CCD data bandwidth. The d70 has also a "highlights" mode which make overexposed areas in the picture blink (no matter which channel is overexposed): this is truly the one most useful to look at overexposure.
If a picture has a high luminance contrast, you may decide to accept a few overexposed pixels. The histogram does not tell you which areas of the pic will lose details. The highlights mode will, and you can make an informed decsion on the importance of these areas to your picture and accept the best compromise.
Thierry
If a picture has a high luminance contrast, you may decide to accept a few overexposed pixels. The histogram does not tell you which areas of the pic will lose details. The highlights mode will, and you can make an informed decsion on the importance of these areas to your picture and accept the best compromise.
Thierry
OldSkoOL
Senior Member
You have to take what that guy says with a pince of salt. He even mentioned forums like this are a waste of time. He says all lenses other than Nikons are trash etc etc...
As far as im concerned the histogram is a very valuable tool with great advantages for digital imaging. I dont even look at the picture most of the time, just the histogram. My photos have been good till now using this method.
If the histogram was really rubbish and that in-accurate then why did Nikon make it available. To me it seems to judge exposure rather well. As mentioned i use it all the time, and use it aswell as NC histogram to calabrated my tone curves and i havent found any reason in 1000 test images and nearly 8k of normal images not to trust its readings.
--
D70 Knowledge Base, curve downloads, my galleries
http://www.pbase.com/oldskoo1/the_curves
http://nikond70.tk
As far as im concerned the histogram is a very valuable tool with great advantages for digital imaging. I dont even look at the picture most of the time, just the histogram. My photos have been good till now using this method.
If the histogram was really rubbish and that in-accurate then why did Nikon make it available. To me it seems to judge exposure rather well. As mentioned i use it all the time, and use it aswell as NC histogram to calabrated my tone curves and i havent found any reason in 1000 test images and nearly 8k of normal images not to trust its readings.
--
D70 Knowledge Base, curve downloads, my galleries
http://www.pbase.com/oldskoo1/the_curves
http://nikond70.tk
fishcatcher
Veteran Member
I'd do some testing along with the grain of salt that I take with everything, except the obvious, that Rockwell pronounces. He may be right and he may be speculating and he may be dead wrong.
I use the blinking hilites rather than the histogram most of the tiem, and I find that the bliking is about 1/3 stop lower than maxed out. I did some practical tests in some contrasty scenes in order to get a feel for how much cushion they put in there and most of the time it bliks about 1/3 stop before you hit the wall. YMMV.
I use the blinking hilites rather than the histogram most of the tiem, and I find that the bliking is about 1/3 stop lower than maxed out. I did some practical tests in some contrasty scenes in order to get a feel for how much cushion they put in there and most of the time it bliks about 1/3 stop before you hit the wall. YMMV.
muskiemouth
Senior Member
Don't tell me you're a Simpsons fan too?
The histogram doesn't show up until after you snapped the shot, so it's only usefull if you intend to take subsequent shots of the same subject and make adjustment from the histogram of the previous shot. That must mean you have the time to recompose and take another shot.
From that one could either:
A: use the highlight feature instead to show overexposure and recomp
or
B: Bracket, baby!!
Nikon really did a number on those of us who are control freaks with all the features and whistles they put on board this camera!
The flexibility of digital photography to sharply reduce the learning curve associated with exposure, lighting and film characteristics has been lost forever in favor of trying to put Photoshop inside the camera so we can all try to get that perfect shot right within the camera without having to touch it in post processing. All this fiddling is an attempt to preset the camera to take the perfect photo, when often times as the subject varies, so does exposure, white balance, contrast etc.
If you're using the camera in a studio and you're always composing basically the same shot, then trying to create the ultimate static setting in the camera may save a bit of time. Otherwise, take the shot, send it to post and use the broad range of tools better designed to give the control freak the power over his composition.
We need to stop banging our heads against the wall in search of the next great "curve" or trying to compose your next shot from a tiny histogram display using a jog/shuttle button and a plethora of camera menus.
Creativity is NEVER static.
Thank you, and I await the supressive fire from those who cash in on the control freak's desire to rule the world!
ps. I'm waiting for a firmware release from Nikon that puts an entire bag of custom color filters in the camera so I can make that sunset really scream!
Then I can start a new thread avalanche.
From that one could either:
A: use the highlight feature instead to show overexposure and recomp
or
B: Bracket, baby!!
Nikon really did a number on those of us who are control freaks with all the features and whistles they put on board this camera!
The flexibility of digital photography to sharply reduce the learning curve associated with exposure, lighting and film characteristics has been lost forever in favor of trying to put Photoshop inside the camera so we can all try to get that perfect shot right within the camera without having to touch it in post processing. All this fiddling is an attempt to preset the camera to take the perfect photo, when often times as the subject varies, so does exposure, white balance, contrast etc.
If you're using the camera in a studio and you're always composing basically the same shot, then trying to create the ultimate static setting in the camera may save a bit of time. Otherwise, take the shot, send it to post and use the broad range of tools better designed to give the control freak the power over his composition.
We need to stop banging our heads against the wall in search of the next great "curve" or trying to compose your next shot from a tiny histogram display using a jog/shuttle button and a plethora of camera menus.
Creativity is NEVER static.
Thank you, and I await the supressive fire from those who cash in on the control freak's desire to rule the world!
ps. I'm waiting for a firmware release from Nikon that puts an entire bag of custom color filters in the camera so I can make that sunset really scream!
Then I can start a new thread avalanche.
Mikhail Bogdanov
Veteran Member
I learn English from Simpsons and photography from Ken Rockwell (as a result i'm getting better at both).
bobm666
Well-known member
This should read "cuts off on the left hand side". The histogram is a plot of the number of pixels (vertical scale) for each luminance value (horizontal scale).
Changing the exposure will move the whole graph left or right, not up or down. If the histogram ends a quarter of the way from the right hand edge but runs up to the left hand edge with lots of pixels there, then you have probably underexposed.
Bob Meyers
Leon Wittwer
Forum Pro
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