Histogram Not Showing Correctly

[kiwilink]

I just shot a few pics with my D7000 and was looking at the Histogram in the Camera and in Photoshop and noticed that the Histogram was almost flatlined in IMATCH.  I rescanned and also did a forced update and no change.  Any idea what I'm doing wrong?  I have attached a screen capture of what the histogram looks in Imatch and what it looks like in Photoshop.  I did not attach the original image here because of the size but I did resave it within Photoshop at a lower quality and attached it.  When I look at it also in Pshop I see a good Histogram but not in Imatch.

Thanks!

Mike

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[Mario]

From the numbers I see for this file (retrieving the low/high value for each channel), the histogram appears to be correct.

There are several high peaks in each channel (peak value over 24000, average about 414). When 'mapping' this peak into the narrow space of the histogram, IMatch has to scale the histogram so that the lowest and the highest value fits into the screen space. And this makes your histogram look rather smashed and flat - because the peak values are so high.

I think Photoshop may somehow scale the other values, or trim the peak in order to produce a more non-linear histogram. Or they use a logarithmic scale. I dunno.
I opened the file in another software which also displays linear histograms, and there the histogram looks like in IMatch.

I'm not sure if I should change the way IMatch calculates histograms in order to remove such peak values, or how to detect a true peak value compared to, say, an almost white value in a histogram which is mostly black, ...

When I remove the topmost peak value from your histogram, the result looks like this:



but that's no longer the 'real' histogram because the peak values don't display.

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[kiwilink]

Mario:

Thanks for the reply.  Take a look at the two attachments here.  These are two different shots DSC_1394.jpg and DSC_1395.jpg.  I took a screen capture of the histogram in IMATCH and in Nikons VNX2 application.    In 1394 the Histograms look very similar but the very next shot (attachment 1395) the histograms don't look at all like each other. 

Is there any chance this has anything to do with the filter I am testing (Variable Neutral Density Filter)?  I doubt it but I thought I would mention it.

Mike


P.S.  Is there anything in the Metadata that recognizes a ND filter when it is attached to the camera lens?  I don't see anything and a search of the web doesn't say much.

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[Mario]

1. Switch the histogram in IMatch to it also shows each channel. You have configured it to show only lightness. Change it in your layout.
2. How should a camera now if and what filter is attached to your lens?