D80 histogram vs histogram on computer

Discussion in 'Digital Photography' started by Martin Sørensen, Dec 16, 2007.

  1. I have a D80 which I am quite happy with. I am shooting RAW,
    postprocessing with Capture One LE.

    I have the colour space set to Adobe RGB, and try to fit the histogram
    to the right without blowing highlights.

    But when I then open the image in C1LE (or PS CS2, or Graphic
    Converter), the histograms have loads of "space" to the right side.
    What is happening?

    Can anyone give me a clue?

    As an aside, I came to the D80 from an FA. What I miss most is the
    shutter release button with the ring around, and then the viewfinder.


    Martin Sørensen, Dec 16, 2007
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  2. Martin Sørensen

    Jim Guest

    Your images are still a bit underexposed. It is hard to get that tiny
    histogram that you see on the camera to match the one which shows up on
    your very large monitor.
    Jim, Dec 16, 2007
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  3. Martin Sørensen

    acl Guest

    The in-camera histograms are produced from the in-camera jpeg, even if
    you are shooting raw (to see this, shoot the same thing twice but with
    different white balance, and notice that the colour histograms
    change). Note that a jpeg is always produced and is embedded into the
    raw file (that is what you are looking at when you zoom-in in-camera).
    The point is that different converters (the camera itself, C1 etc)
    apply different tone curves; so your histograms will look different.

    What you can do is always use a particular curve in your camera (the
    contrast setting; you can even upload one) and work out, by trial and
    error, and for a given white balance and sharpening setting, what the
    in-camera histograms look when you actually get clipping in the raw
    data. But it's too much work.

    Anyway, it's good to keep in mind that the histograms you see will be
    very strongly affected by white balance (and contrast settings), even
    when shooting raw: if you look at actual raw data, it is almost
    impossible to clip the red channel without first clipping the green
    one, even under tungsten light; but shoot a red rose in broad daylight
    and try to get the red channel histogram not to clip in the camera...
    acl, Dec 16, 2007
  4. So, completely normal and the best I can do apart from bracketing?

    To me, it is just striking that often there is (almost) nothing on the
    right-most quarter of the computer histogram, even if I try to hist if
    with the camera.

    Martin Sørensen, Dec 16, 2007
  5. It takes awhile, but you'll get used to the shutter

    However, for exposure control, after you've checked the
    histogram, try moving your "photo information" display
    one setting to the right, so that instead of a histogram
    you have a "blink on overexposure" display, and use that
    to fine tune exposures. I typically use manual
    exposure, but if you like the camera to do it you can
    adjust the Exposure Compensation to get it right on
    target. The trick is to crank in extra exposure until
    it blinks, and then back off just one step (defaults are
    1/3 of an f/stop, but can be set to 1/2). It requires
    "wasting" two or three shots, but developing digital film
    is cheap... :)

    You can then learn to accept blown highlights in certain
    areas, and adjust on others. For example, if there is a
    reflection, or an electric lamp in the scene, let it
    blink, and adjust on the brightest area that should not
    be blown. The single biggest advantage of the blink on
    overexposure display is that you can see where it is
    overexposed, which a histogram does not tell you.

    Basically, if you leave it at 1/3rd f/stop steps you can
    nail exposure to within 1/3rd f/stop virtually every
    time. That's close.
    Floyd L. Davidson, Dec 17, 2007
  6. Martin Sørensen

    Paul Furman Guest

    I agree with acl, what you can do is turn down the contrast, saturation
    and sharpening as far as possible in the menus. This will give a jpeg
    histogram that is closer to the raw file but still not raw.

    I also agree about the blinking overexpose mode, I switch between those
    often. And do look at the 3-color histogram, in particular skies can
    blow out the blue channel making an irretrievably cyan sky when the
    composite histogram looks fine in some applications.

    BTW the viewfinder may not look as good as your old film camera but it's
    one of the better viewfinders available for cropped digital and is
    excellent considering the price of a D80.
    Paul Furman, Dec 17, 2007
  7. Martin Sørensen

    Jim Guest

    No, it not normal. You need to increase the exposure by either switching to
    manual mode or by using exposure compensation. If the right quarter of the
    histogram is blank, then you are underexposing by about 1 stop.

    So, completely normal and the best I can do apart from bracketing?

    To me, it is just striking that often there is (almost) nothing on the
    right-most quarter of the computer histogram, even if I try to hist if
    with the camera.

    Jim, Dec 17, 2007
  8. Martin Sørensen

    Mark Roberts Guest

    This isn't unusual. The histogram you see on the camera LCD is based
    on the embedded JPEG within the RAW file. It is therefore in 8-bit
    color so it's not capable of showing you all the headroom you're
    getting with RAW images.

    Having one full quarter of the histogram flatline sounds a bit
    excessive, but depending on variations in meter calibration and the
    types of scenes you're shooting it's certainly possible when combined
    with the JPEG/RAW discrepancy.

    It's usually OK to clip the right-hand edge of the in-camera histogram
    when shooting RAW, but you have yo learn from experience how much you
    can get away with.

    Some people I know who shoot RAW exclusively change the default JPEG
    settings on their cameras, turning contrast and saturation way down,
    to make the JPEG histogram more accurately represent the RAW file.
    These settings don't change what's in the RAW file, and they'll make
    your JPEG files look flat & washed out (which is why only RAW-only
    shooters use this technique), but you'll get a histogram that looks
    closer to what's in the RAW file.
    Mark Roberts, Dec 17, 2007
  9. Martin Sørensen

    Mike Russell Guest

    Back to the OP's question. I'd be interested in knowing why the upper edge
    of the D80's histogram should be so different from the one shown in the
    editing software, and the responses so far are not particularly satisfying.

    The histogram, for the D80, and AFAIK all SLR's, is after the fact, and does
    not involve SLR sensor technology. Nor should the camera's JPEG settings
    have much of an effect on the histogram:. changes in gamma affect mostly
    the midtones, and not the min or max values. Sharpness, and the output
    color profile, likewise have little or no effect on overall brightness.

    My own personal guess is that it's the raw converter's "exposure" setting
    that is the culprit in this case, but it's only a guess.

    Though I can understand the desire for precision, from a practical
    standpoint, 25% of the histogram is only a half a stop error. Luckily in
    this case it is on the safe side, since what you really want to avoid is
    Mike Russell, Dec 18, 2007
  10. Completely normal for any dSLR. You have to understand, that the light-meter in
    any SLR design system is only a rough rough approximation from what you see, and
    what you see is already an approximation of the full-frame that will be
    recorded. Plus, if you change lenses from anything than other the default
    "normal" lens of 55mm e.q. for which the light-metering system was optimized,
    any other lens' light path will not hit those sensors correctly. Forget about it
    even trying to cope with a long zoom range for any accuracy. Just learn to know
    the differences between particular lenses, their focal lengths, and the
    resulting true histogram that will be provided. Then mentally adjust before each
    shot for that "fudge factor" that you'll have to remember for each lens used and
    each focal length range on any zoom lens.

    You're just finding out something about all dSLR's that most dSLR owners turn a
    blind-eye too (like so many things they do).

    This problem of any auto-exposure or metering system in any SLR light-path
    camera has existed since the SLR design was first implemented.

    Nothing new. Perfectly normal. Perfectly useless for anyone requiring more
    precise metering of their subjects.

    Oh, and don't keep your eye too far away from that viewfinder lens. Any light
    that enters through the lens where your eye is at on that "much desired" optical
    viewfinder will also upset the auto-exposure readings. This is just a few of
    things they didn't want to tell you when they were going on and on about how
    dSLR's are so superior to all other camera designs.

    bobby_robington, Dec 18, 2007
  11. Martin Sørensen

    Mr. Strat Guest

    Have fun with your P&S kiddie toys, moron.
    Mr. Strat, Dec 18, 2007
  12. If you shoot RAW, there is no point setting the color
    space to aRGB. That only changes the way the JPEG
    is processed, which is part of the difference you are
    seeing between the in camera histogram and the
    post-processed histogram.

    For RAW, you are best off setting all of your "in
    camera" conversion parameters to the least possible
    processing. But even then, you have to understand that
    you are looking at the histogram for a JPEG processed by
    the camera and then later comparing that to the
    histogram for an image you've processed using different
    parameters with an external RAW conversion program.

    Two distinctly different images! There is no reason
    they should be the same.

    But if you are using the RAW file, you'll want the
    histogram to be closer to what that is, so don't set it
    up for any significant amount of processing on the in
    camera JPEG.
    True, once you've set the JPEG processing to something
    less than aggressive. I'm not at all certain how much
    effect one can expect to see from that, but you might
    find it interesting to experiment with it and find out.
    See how much difference there is when you change the
    JPEG parameters for camera processing.
    Floyd L. Davidson, Dec 18, 2007
  13. Martin Sørensen

    acl Guest

    Perhaps they are not. However, to demonstrate the point, I took a
    random shot with my D200, raw+jpeg. This one, in fact:
    (it was meant to be used to test some noise reduction technique I
    thought of-a complete disaster). I then processed the raw with
    rawshooter, everything at 0, and opened both the converted file and
    the camera jpeg in photoshop (the camera settings were all to 0 or
    medium, ie sharpening normal, tone compensation/contrast to 0,
    saturation to normal etc). I also made sure the WB of the file
    converted from raw was as close as I could get it to the jpeg. So,
    here are the two histograms:
    (the top is from the jpeg, the bottom from the raw-converted file). As
    I said, I had all controls in the raw converter zeroed out.

    This isn't too surprising: if you use more than one converter
    regularly, it is blatantly obvious that they use completely different
    curves when they convert (eg nikon's converters don't just use a
    simple gamma curve, as far as I can tell etc-but I did no detailed
    tests to work out the curve, although it should not be that hard with
    Well, besides WB, tone compensation (ie contrast in Nikon-speak) does
    have an effect, although less than in the screenshots of the
    histograms I already posted (about half the change seen there). I can
    show examples from my d200 if you want. Also switching bet srgb and
    argb has about the same change in the in-camera histograms, at least
    (and under tungsten light, with bright red objects-I suppose it
    strongly depends the colours). I tried shooting them with my compact
    but it couldn't focus in the low light...
    acl, Dec 19, 2007
  14. Are you sure about that "half a stop"? That would make the D80
    histogram different from most others. In Photoshop, and on Canon
    cameras, the X axis is the gamma-corrected pixel value. The distance
    between the midpoint and the right edge represents about 2.5 stops
    exposure change, not the one stop you'd expect if the X axis represented
    linear intensity. And 25% of the histogram is more than one whole stop,
    not half a stop.

    Dave Martindale, Dec 19, 2007
  15. Martin Sørensen

    acl Guest

    Why 2.5 stops? It depends on the curve used during conversion. I
    showed this before, but here it is again:
    This is the exact same image converted through rawshooter (lower
    histogram) and the jpeg produced by the camera (upper histogram), both
    "converters" at their defaults. Obviously, rawshooter uses a curve
    with a longer shoulder by default. So you can't make a blanket
    statement like "the upper half is 2.5 stops", unless you specify the
    curve used. Isn't this obvious?

    Some raw converters let you see the exact curve used to map from
    linear data to final result (raw magick, for example, and ufraw also,
    I think). Others let you play with shadow contrast/highlight contrast
    sliders (or they may call it shadow compression/highlight compression
    etc, this is the opposite presumably). These allow tweaking the
    shoulder/toe of the curve. I don't see why people assume that if you
    don't touch these (or your converter doesn't have them), or you don't
    modify the curve, then a simple gamma curve is applied.
    acl, Dec 19, 2007
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