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How to read histograms ?

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    Divya
    Divya  3 United States
    29 Aug 2012 - 9:07 PM

    I am a beginner in photography. I was reading last night about exposure and I came across histograms. It got me completely confused Sad. Can someone tell me how to read histograms and how to get correct exposure using histograms ? Smile

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    29 Aug 2012 - 9:07 PM

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    Paintman
    Paintman e2 Member 8858 forum postsPaintman vcard United Kingdom173 Constructive Critique Points
    29 Aug 2012 - 9:17 PM

    This will help

    Basically the histogram shows the tonal information in the photo. This, in most cameras, is a representation of a jpg output and not the RAW information. There is more information held in the lighter parts of the histogram than in the darker parts and that's why it's best to shoot to the right whilst not blowing out the highlights.

    mikehit
    mikehit  56475 forum posts United Kingdom9 Constructive Critique Points
    29 Aug 2012 - 9:28 PM

    In an nutshell, the aim is to take a picture without the curve of the graph hitting the right hand side of the histogram. If too much information is at the limits to the right it means that you have 'overexposed' and you cannot recover any detail from the brighter areas. Similarly if it hits the left hand edge of the histogram it means you have underexposed parts of it and you will lose data in the shadows.

    Usually the single-curve histogram is sufficient - you can on higher-level cameras get the RGB histogram that looks at the red, green and blue channels separately and this can be useful because the red channel is often the first to 'blow' (think photos of red roses or Ferraris).


    The histogram is based on the information in the JPEG not the RAW data (and more precisely, it is based on the jpeg produced by the picture style you have set in-camera). What this means is that if you are shooting RAW, although a picture may look as though the highlight is blown there is a good chance that you can recover an 'extra stop' of detail in post processing.

    Eviscera
    Eviscera e2 Member 81104 forum postsEviscera vcard United Kingdom149 Constructive Critique Points
    29 Aug 2012 - 11:28 PM

    Never be a slave to the histogram.

    Its a useful tool for a measured exposure , but as a creative photographer , ya might want spot and push those shadows/highlights as far as you want.

    Heres a kak image of a seagull on a wall (bottom right) . Overcast light , multi segment and some clipped highlights.

    The abstract (no p.s , no saturation) used spot off the brightest part in the scene and just gave a sense of structure.

    grams.jpg


    Im puzzled why the camera histogram rarely emulates the levels pattern in cs though.

    That would be good to know.

    Last Modified By Eviscera at 29 Aug 2012 - 11:33 PM
    Divya
    Divya  3 United States
    30 Aug 2012 - 2:55 AM

    Thanks Everyone. It helped me a lot Grin

    tepot
    tepot  104416 forum posts United Kingdom
    30 Aug 2012 - 4:26 AM

    in my experience you need to expose so the main peak of the "hill" in the histogram is just right of center, gets a bit tricky though with very contrasty scenes, thats when you need to check the image visually on the LCD screen, when you see bits of white flashing in the LCD screen though indicating over exposure ignore it in favour of the histogram as often as not when you look at it in photoshop, it'll be fine and you have a certain amount of leway if you shoot .RAW anyways.

    Terry.

    MikeRC
    MikeRC e2 Member 93501 forum postsMikeRC vcard United Kingdom
    30 Aug 2012 - 7:00 AM

    ...bookmarking

    cats_123
    cats_123 e2 Member 104023 forum postscats_123 vcard Northern Ireland25 Constructive Critique Points
    30 Aug 2012 - 8:35 AM

    I like to see practical demos of this sort of thing and I find Lightroom works well for me because it allows you to drag the component parts (Blacks, Shadows, Exposure, Highlights, Whites) of the histogram until you get the effect you're looking for. It translates this into sliding scales (e.g. ++or - exposure stops ) which you can then use to improve on your future efforts. Smile

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