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OM-D, Understanding the histogram under the Fn2 button.

Discussion in 'Olympus Cameras' started by Dave in Wales, Jul 9, 2012.

  1. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    I've never used histograms before but thought I have a dabble.

    The 'normal' histogram I can understand but the one under the Fn2 button is a curve that when changed results in plus/minus highlight/shadow values appearing on the SCP.

    I'm probable being a bit thick but what's that all about, I can find nothing in the manual to explain this.

    Pointers to a link would be nice.

  2. DekHog

    DekHog Mu-43 Top Veteran

    May 3, 2011
    Dave, I thought you sold the OM-D?
  3. It's a jpeg tone curve adjustment tool. You can use it to raise or lower highlights and shadows with more finesse than the normal contrast adjustment. It's a "live" tool so that you can see the effects of the adjustments on the screen or viewfinder.
  4. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
  5. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    The curve isn't a histogram.

    The histogram displays the distribution of luminance in the image. The left end of the graph is black, the right end is white, and in between you have the multitude of shades of grey that lie in between. The height of the histogram at any point indicates the number of pixels in the image at that level of luminance. It's an indication of how many pixels in the image are to be found at any given level of luminance. What it displays is information about the light coming into the camera.

    The curves control is different. It's not about the light coming into the camera. It's a graphical display of a flexible contrast control affecting how the camera displays the scene you're shooting on the OLED screen or in the viewfinder, and also how it converts the RAW data from the sensor to a JPG file if you're shooting JPGs rather than RAW. It gives you more control over contrast than the simple numerical contrast setting gives you. It has no affect on your actual photos if you're shooting in RAW though it will still affect how the camera displays the scene and your images while you're reviewing your photos in camera.

    So the histogram tells you about the light levels in the scene you're shooting. The curves display shows you a graphical display of how you want the lighting contrast in the scene handled on your camera's displays and in the JPGs it creates if you shoot in JPG format.

    Bottom line: If you're shooting JPGs and you don't understand the curves control, leave it alone. If you want to use it you're going to have to change the settings from time to time to suit the light you're shooting in and how you want your highlights and shadows treated. If you don't change this setting to suit your circumstances you will end up losing highlight and deep shadow information that you may not be able to recover so it pays to understand this control before you use it.

    I can't point you to a link but if I remember correctly there is a bit about it in the full manual that's available on line and also in pdf format on the CD that came with your camera. If that isn't enough for you, then I'd suggest doing a google search for lessons on using the curves control in photo processing software like Lightroom, Aperture, and Photoshop. The curves control in those applications is basically the same as the control in the OM-D but with a lot more flexibility than the OM-D provides.
    • Like Like x 4
  6. strang

    strang Mu-43 Veteran

    May 7, 2012
    Oh what the tone curve has no effect on RAW? I've been making these adjustments thinking that there are changes like a fool!

    Looks like I'm going to need a grad after all.
  7. jnewell

    jnewell Mu-43 All-Pro

    Jun 23, 2011
    Boston, MA
    It was my understanding that it didn't affect raw files, and that seems confirmed by the posts above. It's easy to make those adjustments, with greater precision, during PP. :smile:
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