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Thread: Using histogram

  1. #1
    New Member ventodimare's Avatar
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    Using histogram

    Hi All,
    I have attached 2 pics with the relative histrograms.
    The 2 histograms look so similar to me that I cannot understand how to use them to choose the best shot: can anybody explain to me which pic I should choose according to the relative histogram?

    Please disregard all the composition rules of the pics: I am still trying to get my head around how to use the histogram.

    Cheers
    Attached Images Attached Images

  2. #2
    Steaphany's Avatar
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    Re: Using histogram

    Welcome to CiC,

    Looking at both histograms, I'd say you have nothing to worry about with either image. The 5079_histogram.png does show slighter brighter pixels in the image, but the main point is neither image has the histogram "climbing the walls" at either end which would indicate exceeding the dynamic range and correspondingly a loss of detail.

    Many of the Internet Histogram articles talk about an ideal histogram contour, but your example here is why an ideal histogram doesn't exist. If you look at your image, just assessing the areas that are bright and dark, the histogram will only show you the relative proportions, i.e. the number pixels that fall into each brightness category, nothing more. If you framing brought more white areas into the scene, that hill on the histogram would grow and since there would be less darks, that area would fall.

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    Nass's Avatar
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    Re: Using histogram

    Ok, simplified answer to prevent confusion.

    A histogram shows you the amount of information in your picture, from dark stuff on the left to light stuff on the right. If you look at the examples above there is a hump on the left - which corresponds to all the dark information you have in those shots (the trees). What you usually want from a pic is lots of information, ie lots of different colours, ranging from pure white to complete black.


    • The histo on the left has information across the entire graph, all the way to the right. And it has a bigger area of dark.
    • The histo on the right has a smaller total area of information, and it doesn't touch the right hand end.


    Therefore, I'd choose the left

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    Moderator Donald's Avatar
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    Re: Using histogram

    As Steaphany's indicates, both Histograms are telling you that you've got useable files from which you can work to produce an image.

    You can, if you really wish, read lots and lots about where the bumps should be to make the 'wonderful' image. Personally, I find such writings excellent for lighting the fire. The production of good images is a human endeavour that is achieved by the human eye seeing and passing information to the brain, which then processes the information and makes decisions. It isn't and must never become, a mechanical 'thing' informed by mechanically produced data, such as a Histogram.

    The Histogram is an aid. It tells you, as Steaphany has written, whether or not you've got pixels climbing the walls at either end. It also shows you the spread of tones contained in the image. It doesn't tell you where they are.

    So, my answer to your question - "... which pic I should choose according to the relative histogram?", is please don't try to use it for that purpose. User it as a means of assisting you in the human decision-making process of deciding which one 'works' best according to your eye. And in this case - the assistant is telling you they're both good to go. But which one do you now prefer to take to the next stage and turn into a picture.

    By the way - Hello and welcome to CiC. I usually to my 'hello's' in the 'New member' thread, but since you've pitched right in with a question, I'll just do that here.

    You've maybe seen that most of us tend to use our real names on here. It makes communication more friendly and CiC is that sort of site. Did you know you can go to Edit Profile and enter your proper name under 'Real Name'. Then it will appear underneath your Username in all your posts. You can also enter your location so that it does the same, just as in my details alongside this message. Then we all know where everyone is in the world.

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    Re: Using histogram

    Or to put things another way, "the histogram tells you how it IS, not necessarily how it SHOULD BE".

    Personally, I pretty much only use it to reveal the extent of any under-exposure; if the histogram stops well short of the right hand side - AND it's an image with highlights - then I may increase the exposure for a subsequent shot.

    In terms of there being "an ideal bell shape" etc, that's just plain wrong.

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    Re: Using histogram

    I've been trying to use the histogram after taking a shot just to check for proper exposure.

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    Re: Using histogram

    Quote Originally Posted by georgem View Post
    I've been trying to use the histogram after taking a shot just to check for proper exposure.
    Hi George,

    It can help with exposure, but it has to be interpreted in the context of the image. As a case in point - if the histogram stopped 3 stops short of the right hand side then a lot of people's first reaction might be to say "it's severely under-exposed"; if the shot was of a bride in a white dress then this indeed would be the case - but on the other hand - if it was a shot of a black cat on a black rug, then it may well be correctly exposed (black isn't a highlight, and it would be incorrect to expose it as a highlight).

    The histogram is merely a record of where the tones lie - unfortunately, this bares no co-relation what-so-ever with where the tones SHOULD lie for any given image.

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    Re: Using histogram

    The histogram is merely a record of where the tones lie - unfortunately, this bares no co-relation what-so-ever with where the tones SHOULD lie for any given image.
    How do you know where the tones SHOULD lie? Is it personal preference or is there a technocal way to do it.

    I have been reading a lot about histograms as well and post production of images in general and no one seems to get to the nitty-gritty enough for me. I have photoshop CS4 and have been shooting in raw and JPEG, like the "big guys" recommend but don't know where to even begin to use the software.

    Thanks for the question and the answers so far! Look forward to more.

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    Re: Using histogram

    Quote Originally Posted by ddp4me View Post
    How do you know where the tones SHOULD lie? Is it personal preference or is there a technocal way to do it.

    I have been reading a lot about histograms as well and post production of images in general and no one seems to get to the nitty-gritty enough for me. I have photoshop CS4 and have been shooting in raw and JPEG, like the "big guys" recommend but don't know where to even begin to use the software.

    Thanks for the question and the answers so far! Look forward to more.
    You need the "Histogram Prayer" ...

    "Darks to the left - Lights to the right - and heaven help me protect the holy highlights"

    In all seriousness, that's one of those "how long is a piece of string" type questions -- there's no one answer that fits every occasion. As a rule-of-thumb - for lansdcape - we generally want an image to use the whole tonal range (otherwise it may look flat), so with a histogram in the likes of Photoshop, you generally won't want any "flatline" between the clipping points and where the tonal ranges start and stop (in reality I generally bring the clipping points inside the tonal range to force a significant area to pure black and a (smaller) area to pure white). I say "the histogram in Photoshop" though - you won't be able to do this in camera because the dynamic range of the camera is generally too big.

    With regards to portraiture (and images in general), the short answer is "whatever looks best"

    Hope this helps

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    Re: Using histogram

    I'm noticing that the consensus by the experienced photographers here is that the histogram may simply be too little information in a form that does nothing but mislead and distract novice photographers. Authors on the subject of digital photography end up putting to much effort in explaining how to interpret and apply the histogram when, in actuality, it has little to no real value.

    Here is a practical alternative that will give you some real information to work with, ignore the histogram and turn on the Exposure Warning, Over Exposure Warning, or "Blinkies". This way when you chimp your photos on your camera, the image areas that "climb the walls" in the histogram will be highlighted. You will not only see how much of the elements in the image have been clipped, but you'll also know what in the scene is causing the problem. ( Just try to glean that from a histogram ! )

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    Re: Using histogram

    Quote Originally Posted by Steaphany View Post
    I'm noticing that the consensus by the experienced photographers here is that the histogram may simply be too little information in a form that does nothing but mislead and distract novice photographers. Authors on the subject of digital photography end up putting to much effort in explaining how to interpret and apply the histogram when, in actuality, it has little to no real value.

    Here is a practical alternative that will give you some real information to work with, ignore the histogram and turn on the Exposure Warning, Over Exposure Warning, or "Blinkies". This way when you chimp your photos on your camera, the image areas that "climb the walls" in the histogram will be highlighted. You will not only see how much of the elements in the image have been clipped, but you'll also know what in the scene is causing the problem. ( Just try to glean that from a histogram ! )
    Hi Steaphany,

    In practice, I use a combination of histogram and blinkies;

    - The blinkies are useful because they give a "heads up" that not only is over-exposure a possibility, but it also gives an indication of where (so I can decide if those areas are important, or if they can "take a bullet for the team")

    - The histogram (to me anyway) is useful because it gives the degree of any under-exposure. The following 2 images are a "real world" example from last night's shoot. First image was 10 sec exposure, but the camera's histogram indicated it was about 4 1/2 stops under-exposed - so the 2nd shot (below it) was 4 minutes.

    Using histogram

    Using histogram

  12. #12
    Steaphany's Avatar
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    Re: Using histogram

    Quote Originally Posted by Colin Southern View Post
    In practice, I use a combination of histogram and blinkies;

    - The blinkies are useful because they give a "heads up" that not only is over-exposure a possibility, but it also gives an indication of where (so I can decide if those areas are important, or if they can "take a bullet for the team")

    - The histogram (to me anyway) is useful because it gives the degree of any under-exposure.
    An excellent mix Colin. I feel this thread has evolved into a practical direction that could be helpful to newbies.

    I've noticed that the CiC histogram tutorials fall under the Photo Editing Tutorials, not the Camera Equipment nor the Learn Photography Concepts. I proposed that a tutorial addressing In-Camera Exposure Evaluation be written to include the use of the camera histogram and blinkies together to aid in understanding the characteristics of an image and point to potential exposure setting alterations to compensate. I also suspect that a novice photographer who is just beginning to get a handle on image capture may not realize where to look for the existing histogram tutorials, so a camera specific tutorial may help.

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    arith's Avatar
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    Re: Using histogram

    Quote Originally Posted by ventodimare View Post
    Hi All,
    I have attached 2 pics with the relative histrograms.
    The 2 histograms look so similar to me that I cannot understand how to use them to choose the best shot: can anybody explain to me which pic I should choose according to the relative histogram?

    Please disregard all the composition rules of the pics: I am still trying to get my head around how to use the histogram.

    Cheers
    If it was shot in RAW I would use the first, but if it is JPEG then I would use the second. The first looks like it could be exposed to the right but you will have to check for blinkies or take another 1 stop darker and keep both.


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    Re: Using histogram

    Quote Originally Posted by Steaphany View Post
    I've noticed that the CiC histogram tutorials fall under the Photo Editing Tutorials, not the Camera Equipment nor the Learn Photography Concepts. I proposed that a tutorial addressing In-Camera Exposure Evaluation be written to include the use of the camera histogram and blinkies together to aid in understanding the characteristics of an image and point to potential exposure setting alterations to compensate. I also suspect that a novice photographer who is just beginning to get a handle on image capture may not realize where to look for the existing histogram tutorials, so a camera specific tutorial may help.
    Thanks Steaphany,

    I'll bring it to Seans attention.

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