Understanding the Histogram

This is a discussion on Understanding the Histogram within the Post-Processing forums, part of the Photography Tips category; Originally Posted by twinkle_turnip Kim- I don't know where your background is, but mine is in traditional ZONE SYSTEM black and white photography. So correlating ...


Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 33
  1. #21

    Join Date
    Jul 2010
    Location
    Oregon
    Posts
    1,481
    PHOTO EDITING OK
    Quote Originally Posted by twinkle_turnip View Post
    Kim- I don't know where your background is, but mine is in traditional ZONE SYSTEM black and white photography. So correlating zone placement with histogram placement is important.
    T_T,

    I am not sure what background I am from or if it matters I am not sure where I am headed either.

    I have not done much B&W and not studied the Zone System much as there is just too much information to study it all. Ansel A. struggled with explaining the Zone System as he was a much better photographer then he was a teacher, he did improve on explanation in his last few books though.

    Isn't Hurter and Driffield Curves based more on the sensitivity of light-sensitive materials then the darks to brights indicated as already recorded on the histogram (a log of opacity versus the log of exposure)? I am pretty sure it is all related somehow but I don't care to try to make a H&D Curve for my sensor. How would that work? Thinking about it a bit and a bit is enough for me the H&D Curve kind of reminds me of the Curve features we have in PS, as a kind of H&D Curve after the fact (capture). I am sure this all could go way over my head quickly and in fact I am sure it already has.
    I don't think I have the desire to go further in that direction and it seems like I may be headed towards Aunt Marys peach orchard...
    and so on to other things for me.
    KimR

    Comments and Critique are always encouraged, considered and appreciated. Thank in advance too.

  2. #22
    Senior Member
    Join Date
    Oct 2009
    Location
    Billings, MT
    Posts
    923
    PHOTO EDITING OK
    Well. That's essentially what camera profiling does, right? Making an HD-like curve for the sensor? But i don't really think that that level of precision is necessary either, at least in terms of exposure. Hardly anyone went that far into the zone system anyway, and I am not sure Adams would have either if the government wern't paying him to do it.

    I myself never did much beyond the basics that most people learn in college, I referred to factory data concerning development time verses density, but never made a chart of my own and I don't know anyone who has. In fact, I'm not even sure I was ever in a dark room that had a working densitometer, or at least one that didn't require a substantial investment in dust-off to actually use.

    With multi contrast paper most people I think focused more on extending dynamic range than getting the "perfect", print ready negative. This is more in line with what we're expecting from our histograms today, anyway.

    The following may be inaccurate in places (and looking back prob just me rambling):

    I did a quick little test. And sure enough when you expose a flat wall at Zone 8(ish) and stop down once to Zone 7, the jump on the histogram is much larger than if from Zone 4 to Zone 3. If I am visualizing this right, this would imply that far less exposure is needed to record lighter shades than darker shades. As a result the camera is not linearly sensitive to exposure despite that the theoretical film, the RAW file, is.

    As a result the left side of the histogram is able to hold more information about the subject taken because it correlates to fewer tonal zones. If, for example, if the metered Zones 6, 7 and 8 exist between levels 2046 and 4092 and the metered zones 2, 3, 4, 5 and 6 all exist between levels 0 and 2046 then the discrete steps between zones 2-6 would be greater than zones 6-8 as the smaller range, the hilights, occupies an area of the histogram that represents more discrete levels of grey and as result more useful information can be held in this region as well.

    SO THEN! (aha!) you wouldn't correlate the whole grey scale to any given zones, but rather the data that exists within the histogram since where you end up placing any given zone on the grey scale is relevant only to the other zones that reside elsewhere on the grey scale. Despite that it's much lighter than how we saw the scene, if Zone 0 is at L2046, then it's still the darkest tone in the exposure.

    Duh, friggin duh!
    bear with me. i don't have an escape button...

  3. #23
    Senior Member
    Join Date
    Feb 2009
    Location
    Ontario, Canada
    Posts
    1,126
    PHOTO EDITING OK
    Well this has been fascinating. I've always tended to slightly underexpose because I tend to blow out highlights, especially in the sky, and I've thought a less-exposed image looked richer. I'll have to start trying to lighten up a bit.

    Other than that, I'm not sure I've found a reason here to use the histogram. I'm not sure if I'd use it more if I had full-Photoshop capabilities rather than Elements, or if I knew of a way to correct colour with camera settings (besides white balance). Is this a case of newbies don't need to use it yet, or should be using it more?
    Marie
    Nikon D5000, Nikkor AF-S 18-55mm VR f/3.5-5.6,
    Nikkor AF-S 55-200mm f/4-5.6

  4. #24
    Senior Member
    Join Date
    Aug 2010
    Posts
    109
    PHOTO EDITING NOT OK
    Quote Originally Posted by watergirl View Post
    Well this has been fascinating. I've always tended to slightly underexpose because I tend to blow out highlights, especially in the sky, and I've thought a less-exposed image looked richer. I'll have to start trying to lighten up a bit.
    ...
    I tend to underexpose as well, for a very specific reason. Since each color can saturate separately, if you have a bright color and overexpose, the color can shift: suppose you have a light blue (63,63,127) and overxpose 1 stop, the color will now be 126, 126, 254 (in 8 bit mode) and the color is preserved. If you now overexpose a bit more than 1, the ratio between red green and blue changes and the appearance of the color will be different. I rather have a bit more noise than a color shift. Granted, the same can be said for dark colors, but the color shift will be definitely less noticeable.

    Paolo

  5. #25
    Senior Member
    Join Date
    Oct 2009
    Location
    Billings, MT
    Posts
    923
    PHOTO EDITING OK
    Marie- I think looking at the histogram as more of a reference than something to "use" would be more helpful. It's just a way to quickly look at what values there are.

    Paolo- Typically when you're doing this you don't over expose more than 1 stop anyway, and I have some trouble with the idea of a "proper exposure" to start with. But that is an very interesting observation, is it because of the second green "channel"?
    bear with me. i don't have an escape button...

  6. #26
    Nikon Shooter
    Join Date
    Aug 2010
    Location
    Eatontown, NJ
    Posts
    1,006
    PHOTO EDITING OK
    Quote Originally Posted by watergirl View Post
    Other than that, I'm not sure I've found a reason here to use the histogram. I'm not sure if I'd use it more if I had full-Photoshop capabilities rather than Elements, or if I knew of a way to correct colour with camera settings (besides white balance). Is this a case of newbies don't need to use it yet, or should be using it more?
    Per your signature, you're using a D5000 (I do too)... absolutely use the histogram. The D5000 can display it right on the screen when you shoot a picture.

    Your eyes adjust to the scene. Your eyes also adjust to the display on the back of the camera. There's no way when you shoot a picture to look at that screen and tell whether something is slightly over or underexposed, and whether you have clipped highlights or colors. But the histogram doesn't lie. Displaying the histogram along with the image (and it is easy to switch between the larger image and the smaller image + historgram on the display). Let's face it, that 3 inch screen is great, but it's not a 20" color corrected high resolution monitor. And viewing it in different lighting can be misleading.

    When I shoot a new scene, I absolutely check the histogram right on the camera until I'm happy with the exposure. If the opportunity presents itself, I bracket from there.

    These guys are discussing some advanced concepts with the histogram. And they have some valid points. But even if you're a beginner and really don't understand all the advanced stuff, at least learn the basics of a histogram, especially when your camera can show you right when you take the picture exactly what you have and allow you to make decisions before leaving the shoot.

    The histogram is great in post processing, but, in my opinion, it's strongest point is on-site feedback while you are shooting pictures. It allows you to shoot with even more confidence.

    Regards,
    Marlo

    Check out my blog! --- http://marlomontanaro.wordpress.com

  7. #27

    Join Date
    Jul 2010
    Location
    Oregon
    Posts
    1,481
    PHOTO EDITING OK
    Quote Originally Posted by watergirl View Post
    Well this has been fascinating. I've always tended to slightly underexpose because I tend to blow out highlights, especially in the sky, and I've thought a less-exposed image looked richer. I'll have to start trying to lighten up a bit.

    Other than that, I'm not sure I've found a reason here to use the histogram. I'm not sure if I'd use it more if I had full-Photoshop capabilities rather than Elements, or if I knew of a way to correct colour with camera settings (besides white balance). Is this a case of newbies don't need to use it yet, or should be using it more?
    There is a lot of information to consider. To try to expose under, over, in middle are all thing each individual photographer must consider for their own work, a particular way any photographer does it no more right or wrong the the next. We must pick the path we go down for our own goals and results. There are reasons for each technique and this can of course change from one shooting situation to another. I see Paolo has just responded with reasons he shoots slightly under and as soon as I am done typing this reply I will be studying and considering those reasons with open mind with the hope I may learn from him.

    On using the Histogram -
    It is my opinion that the Histogram is probably the most important tool that we have at our disposal. It is as important when using Elements as it is when using other versions of Photoshop or any other software. I have been shooting digitally and processing for over 10 years and as I learn more and more about the histogram it become more and more important too. It is now just second nature for me to use the histogram of camera and software to check my judgment. With lots of practice and experimentation while shooting and processing IMO my judgment of what is required in a situation has improved (as anything we practice usually does) so I suppose in some ways the histogram becomes less important as our abilities become strong to make accurate judgment calls (of settings, etc.) However because of habit and knowing the power I have in using the histogram it is something I will never stop doing ~ I just do it. It is there and I automatically refer to the information it provides me.

    QUOTE
    Is this a case of newbies don't need to use it yet, or should be using it more?
    That is a good and interesting question I believe. My personal opinion is that the histogram is as important to a newbie if not more so as it is to a seasoned photographer/processor. The histogram is there, it is handy and it is really 'a pretty simple and powerful tool' so my advice is learn about and from it, use it routinely to improve your work. Once we learn how to read our histograms correctly they can and will reveal to us what is there rather then what our eye/brains make us think is there (20-20 vision or not our eyes will trick us).


    KimR

    Comments and Critique are always encouraged, considered and appreciated. Thank in advance too.

  8. #28

    Join Date
    Jul 2010
    Location
    Oregon
    Posts
    1,481
    PHOTO EDITING OK
    Quote Originally Posted by PenguinPhotoWorks View Post
    Quote Originally Posted by watergirl View Post
    Other than that, I'm not sure I've found a reason here to use the histogram. I'm not sure if I'd use it more if I had full-Photoshop capabilities rather than Elements, or if I knew of a way to correct colour with camera settings (besides white balance). Is this a case of newbies don't need to use it yet, or should be using it more?
    Per your signature, you're using a D5000 (I do too)... absolutely use the histogram. The D5000 can display it right on the screen when you shoot a picture.

    Your eyes adjust to the scene. Your eyes also adjust to the display on the back of the camera. There's no way when you shoot a picture to look at that screen and tell whether something is slightly over or underexposed, and whether you have clipped highlights or colors. But the histogram doesn't lie. Displaying the histogram along with the image (and it is easy to switch between the larger image and the smaller image + historgram on the display). Let's face it, that 3 inch screen is great, but it's not a 20" color corrected high resolution monitor. And viewing it in different lighting can be misleading.

    When I shoot a new scene, I absolutely check the histogram right on the camera until I'm happy with the exposure. If the opportunity presents itself, I bracket from there.

    These guys are discussing some advanced concepts with the histogram. And they have some valid points. But even if you're a beginner and really don't understand all the advanced stuff, at least learn the basics of a histogram, especially when your camera can show you right when you take the picture exactly what you have and allow you to make decisions before leaving the shoot.

    The histogram is great in post processing, but, in my opinion, it's strongest point is on-site feedback while you are shooting pictures. It allows you to shoot with even more confidence.
    PPW,
    IMHO ~ Very good and accurate. This has been a good thread, thank you for joining in as it is often important to consider information from someone who uses the same equipment too (D5000).


    QUOTE
    But the histogram doesn't lie.
    Right On! Our eyes & though they are amazing do at times trick (lie to) us.


    KimR

    Comments and Critique are always encouraged, considered and appreciated. Thank in advance too.

  9. #29
    Senior Member
    Join Date
    Feb 2009
    Location
    Ontario, Canada
    Posts
    1,126
    PHOTO EDITING OK
    Thank you for responding to my question, this thread has been very informative and helpful.

    Like so much I've learned in photography, it sounds like the histogram is something that you have to stop and figure out at first, and then it will just be second nature to use it. Usually at that point I wonder what on earth I was doing before I used it.

    I already know that I have to slow down when taking pictures. I'm normally a very methodical person but I just get so excited that I end up rushing. Checking the histogram will be a good way to remind me to stop and evaluate what I'm doing. At a time when I can still do something about it.

    Marie
    Nikon D5000, Nikkor AF-S 18-55mm VR f/3.5-5.6,
    Nikkor AF-S 55-200mm f/4-5.6

  10. #30
    Senior Member
    Join Date
    Oct 2009
    Location
    Billings, MT
    Posts
    923
    PHOTO EDITING OK
    Quote Originally Posted by KimR View Post
    My personal opinion is that the histogram is as important to a newbie if not more so as it is to a seasoned photographer/processor.
    I totally agree! I haven't been shooting digital for long, and there are some challenges associated with the transition. I tend to spend more time looking at the histogram than looking at the screen. For one because I'm more interested in recording as much detail as possible rather than trying to make an exposure look exactly how I want it to in the camera. I think this attitude had it's place with slide film and color dark room printing. But any more I kind of feel like it's an excuse to avoid learning how to make exposures that produce flexible files.

    The instant feedback I think kind of makes people think that digital is easier than film, but I think to fully utilize the technology there are a lot of considerations that go beyond looking at the preview on the screen. And that is where the histogram comes in handy so that you can analyze what is actually happening.

    I think right now we're about where photography was before the zone system, with a lot of theories and techniques scattered all over but without any unified system to get the most from the tools we are using.
    bear with me. i don't have an escape button...


 
Page 3 of 4 FirstFirst 1234 LastLast

Remove Ads

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •