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Why are these two histograms different?

Kommentare

13 Kommentare

  • MikeFromMesa
    I am far being being knowledgeable about the different histograms but I suspect they are not measuring and displaying exactly the same things.

    If you go to the Exposure adjustments, select an image and then adjust the low/medium/highlight controls on that histogram to adjust the shadow, mid tone and highlights in the image you shift the histogram image accordingly. You do not adjust the Levels histogram and I suspect that is working in accordance with the intentions of the developers. As it is I only pay attention to the actual histogram.
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  • Permanently deleted user
    [quote="MikeFromMesa" wrote:
    I am far being being knowledgeable about the different histograms but I suspect they are not measuring and displaying exactly the same things.

    If you go to the Exposure adjustments, select an image and then adjust the low/medium/highlight controls on that histogram to adjust the shadow, mid tone and highlights in the image you shift the histogram image accordingly. You do not adjust the Levels histogram and I suspect that is working in accordance with the intentions of the developers. As it is I only pay attention to the actual histogram.


    When all setting are rest they have to be measuring the same thing as no changes are being made.

    As far as the histograms working in accordance with the intentions of the developer...... why?
    Why would you want to show a histogram that shows clipped black when they are not.

    Also the levels histogram updates when certain other tools are used and does not when other tools are used despite very apparent changes are being made.
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  • ---
    ...well it is rather simple. the histogram shown in the histogram panel takes the selected output color space profile into account.
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  • Lionel12
    As mentioned the top histogram is in the output color space
    The levels histogram show the data after WB, film curves and input profile, and if this clips we show clipping. To get the "rest" of the data (normally the red channel since Red-gain is almost 2), you have to lower exposure and get the "recovered" part of the data, or you use the highlight recovery slider.

    The Curve tool is a third histogram - running after the level changes, hence it should not change with a curve.

    -Lionel
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  • MikeFromMesa
    Thank you for the responses. I guess I learned something today.

    And, for what it is worth, I verified that what Lionel12 posted is correct. I opened C1, selected an image and set it back to its original (unadjusted) state and the two histograms matched.
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  • Permanently deleted user
    [quote="MikeFromMesa" wrote:
    Thank you for the responses. I guess I learned something today.

    And, for what it is worth, I verified that what Lionel12 posted is correct. I opened C1, selected an image and set it back to its original (unadjusted) state and the two histograms matched.


    The first screenshot is with all adjustments reset:

    https://farm6.staticflickr.com/5565/14669887236_49c42776dc_c.jpg

    The histograms are not the same.

    Even with the base characteristics set to "Phase One Effects No Color Correction" and the curve to linear response
    the two histograms are not the same:

    https://farm4.staticflickr.com/3877/14690000916_fdf021dfae_c.jpg

    Shadows are still shown as clipped in the levels tool.
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  • ---
    ....what you see it is related to the color transformation from the camera to the output profile. set the output profile to embed the camera profile and the histigrams are the same.
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  • Permanently deleted user
    @Horseoncowboy
    +1
    The concepts of Colorimetry were still the path a browse... 😉
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  • ---
    i played a little more with profiles and histograms and now i´m sure there is something strange going on.

    when i process an image containing deep blacks with no adjustments, linear and output set to embed camera profile the c1 histogram shows black clipping ( but not the clipping warning - set to 0 ). in ps cc the histogram of the processed image looks different and has now sign of clipping. so for me this is a shows that either the calculation of the histogram in c1 is rather imprecise or a unknown kind of black point adoption takes place.
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  • Permanently deleted user
    I have the same histogram with settings to zero!
    https://dl.dropbox.com/s/vffcz7no9n3hxeh/Capture%20d%E2%80%99%C3%A9cran%202014-07-22%20%C3%A0%2011.54.10.png
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  • SFA
    [quote="Horseoncowboy " wrote:
    i played a little more with profiles and histograms and now i´m sure there is something strange going on.

    when i process an image containing deep blacks with no adjustments, linear and output set to embed camera profile the c1 histogram shows black clipping ( but not the clipping warning - set to 0 ). in ps cc the histogram of the processed image looks different and has now sign of clipping. so for me this is a shows that either the calculation of the histogram in c1 is rather imprecise or a unknown kind of black point adoption takes place.


    What happens if you don't embed the camera profile?


    Grant
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  • ---
    https://dl.dropboxusercontent.com/u/149 ... nachm..png

    c1 7.2.3 canon 5d3 generic profile linear no adjustments to 16 bit tiff a rgb ps cc 2014


    ...so who is able to explain this ?
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  • Permanently deleted user
    I have the same histogram in PS and C1. TIFF prophoto in two software.
    https://dl.dropbox.com/s/m5apv7u5jk2s5kx/Capture%20d%E2%80%99%C3%A9cran%202014-07-22%20%C3%A0%2016.22.13.jpg
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