Speaking of histograms

Discussion in 'Image Processing' started by Uwharrie, Jul 19, 2012.

  1. Uwharrie

    Uwharrie Mu-43 Veteran

    239
    May 10, 2012
    North Carolina
    Lynne Ezzell
    Can someone point me to tutorials or other info on how to properly use histograms both in initial exposure and post processing?
     
  2. Bill

    Bill Mu-43 Regular

    176
    Apr 15, 2009
    Brisbane, Australia
    Bill (really)
    • Like Like x 3
  3. jloden

    jloden Mu-43 Hall of Famer

    May 15, 2012
    Hunterdon County, NJ
    Jay
    I was going to post the same link - good article that helped me understand the purpose of my histogram, beyond blocking screen real estate on the EVF :biggrin:
     
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  4. Uwharrie

    Uwharrie Mu-43 Veteran

    239
    May 10, 2012
    North Carolina
    Lynne Ezzell
    Thanks. That did help!
     
  5. Ian.

    Ian. Mu-43 All-Pro

    Mar 13, 2013
    Munich
    Ian
    The only use I get out of a histogram is where the top and bottom of the exposure ends. Making sure I dont push it out of range or waste any useful range. Are there any other uses for looking at the histogram? Do people use the actual shape or distribution for anything?
     
  6. RobWatson

    RobWatson Mu-43 Hall of Famer

    I use histogram analysis for some specialized needs but never in camera or for gauging exposure. "Wasted real estate" on the EVF camp is where I sit. Consider that the in camera histogram is generally based on the jpeg and limited to 8 bits per color channel (cameras have 10-16 bits of data) and even that spare data cannot be displayed in a detailed way even if it filled the display screen. Besides a rough guide an under/over exposure (for which there is another tool) pretty much useless. I know there is a group of folks that think histograms are an indispensable tool but ...

    Before digital what did those poor film guys use for histograms if it is such a valuable tool how did anyone ever take a decent exposure without one?

    My biggest concern about reliance on the histogram is that the "density" of information displayed is highly dependent on the subject matter. For example a field of stars will have a histogram essentially all with values heavily to the black and so few values showing saturated stars that it does not even show in the histogram but blown stars are a huge problem. In the opposite side shooting flying bird against a sky has the histogram pretty much pegged at white but the primary subject (the bird) is lost in the black which also does not show in the histogram! So how exactly does one use a toll which cannot even show the subject one is interested?

    For some subjects the histogram needs to be displayed in a log/linear scale or log/log scale to be of any use - until histogram tools allow more flexibility in configuring the display they will continue to be of limited use.

    "Possibly the most useful tool available in digital photography is the histogram." Hardly. Most over rated - yes. Naturally folks should know how to extract useful info from all the tools in the kit but once one becomes proficient in understanding histograms their utility for guiding exposure is quickly exposed as very limited.
     
  7. mzd

    mzd Mu-43 Veteran

    241
    Nov 30, 2010
    Wisconsin
    i can say i rarely use it when shooting. i do have my camera set to show blinking clipped highlights though. if my shot shows excessively clipped highlights, i'll adjust exposure and re-shoot. i guess if i used the histogram i could make that adjustment before i fire the shutter, but since i shoot raw, there is a decent amount of highlight recovery i can do while editing.
    and that is where i do make use the histogram all the time - editing.
     
  8. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    Feb 8, 2011
    Pacific Northwest, USA
    Keith
    As far as I am concerned looking at where the upper and lower values are is about the limit of what you can do with the histogram (at least in camera). The shape is really dependent on the scene and there's basically nothing you can do about that (unless you're in a controlled lighting situation). Any spike on the right or left side of the histogram is going to indicate an area with lost shadows or blown highlights. You can adjust your exposure to compensate for these.

    The only other thing to keep in mind is that the sensor captures much more "information" in the right area of the histogram than in the left, which is something you may want to keep in mind when adjusting exposure. This phenomenon leads to the "expose to the right" (ETTR) philosophy.
     
  9. veereshai

    veereshai Mu-43 Top Veteran

    777
    May 12, 2011
    Arlington, VA
    Others have given you all the good responses/links there exist for histograms. However, if you're using OM-D, I've found that highlight/shadow "blinkers" work much better for initial exposure. I just find it difficult to keep an eye on the histogram as I am composing an image and the blinkers have really helped me in that regard.
     
  10. Ian.

    Ian. Mu-43 All-Pro

    Mar 13, 2013
    Munich
    Ian
    Thanks. I don't use the histogram in the camera. But what about the histogram on the PC for corrections and raw processing. It is here I pay attention to the high and low end. But, I have not seen any reason to pay any attention to the shape in between.
     
  11. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    Feb 8, 2011
    Pacific Northwest, USA
    Keith
    Really the only thing I look at with the histogram in post is to make sure that the graph reaches both ends (i.e. making the blacks black and the whites white). This is generally one of the first things I do (after cropping and perhaps adjusting the white balance) to every image I process.
     
  12. Ian.

    Ian. Mu-43 All-Pro

    Mar 13, 2013
    Munich
    Ian
    Great thanks. Same here. I just got the impression some people like to wrap it up in a mystique.
    Anyway, I've yet to see a PC histogram display that enlarges the ends. So you can adjust the end slopes accurately to fall just short of the ends.