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Levels histogram
#1
Hi everybody,

I'm using GIMP 2.8.18 and when I have an image selected and I open the Color/Levels view it does NOT include a histogram.  In my Internet searches there is always a histogram produced.  Is there away to turn this property on?

Your assistance is greatly appreciated.

TC
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#2
What operating system are you using?

What do you see instead of this for Colors>>Levels
   
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#3
As Kevin points out , if you are not seeing the full dialog then something is wrong, otherwise

You can open a histogram as a separate dock 
Colors -> Info -> Histogram and that will follow the sliders on the Adjust Color Levels dialog
   

The Edit These Settings As Curves brings up the Curves tool, so IMHO you might as well start with that in the first place.

An alternative for editing as curves, the g'mic plugin http://www.gmic.eu has some excellent filters.
   
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#4
(01-20-2017, 08:09 PM)Kevin Wrote: What operating system are you using?

What do you see instead of this for Colors>>Levels

Hi Kevin what you're showing is what I want to see but what I am ALWAYS seeing for any image (so far) is:

Humm I don't seem to be able to add an image to this display - see attachment.

TC
[img]file:///C:/Users/PAEnterprises/Desktop/LevelsDialog1.png[/img]

(01-20-2017, 08:21 PM)rich2005 Wrote: As Kevin points out , if you are not seeing the full dialog then something is wrong, otherwise

You can open a histogram as a separate dock 
Colors -> Info -> Histogram and that will follow the sliders on the Adjust Color Levels dialog


The Edit These Settings As Curves brings up the Curves tool, so IMHO you might as well start with that in the first place.

An alternative for editing as curves, the g'mic plugin http://www.gmic.eu has some excellent filters.

Sorry Kevin - I' using Window 10, 64bit

Rich when I open the Levels dialog using the Colors/Info/Histogram I get the same EMPTY Histogram section!

IMHO seeing the histogram will aid me in setting the proper adjustments.  Also have tried to make changes even without the histogram I find that NOTHING is actually changed!

I'm not doing something right.

TC

FYI, I get no histogram when I open the Curve Dialog as well.

TC


Attached Files Image(s)
   
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#5
The Levels tool (and therefore the histogram) is restricted to the selection, and is "alpha-weigthed" (ie, pixels contribute proportionally to their opacity). I get this kind of empty display if the selection includes only transparent pixels... The Histogram display works the same way, so do you have visible histogram in it?
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#6
(01-20-2017, 11:47 PM)Ofnuts Wrote: The Levels tool (and therefore the histogram) is restricted to the selection, and is "alpha-weigthed" (ie, pixels contribute proportionally to their opacity). I get this kind of empty display if the selection includes only transparent pixels...  The Histogram display works the same way, so do you have visible histogram in it?

Thanks Ofnuts, I thought I was selecting the image before I selected levels.  Let me play with it a little to better understand what is happening.  That would certainly explain why changes made in the dialogue were not changing the image.

TC
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#7
Looking throwcodes screenshot, nothing there but...

Might be worth a mention, if the levels appears almost empty then changing the mode from linear to logarithmic will give some visual information.
   
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#8
(01-21-2017, 09:33 AM)rich2005 Wrote: Looking throwcodes screenshot, nothing there but...

Might be worth a mention, if the levels appears almost empty then changing the mode from linear to logarithmic will give some visual information.

Thanks everybody, its working now.  I've done a lot of testing and the only way I can get NO histogram (NOW) is to select just the Alpha in an image.  I don't believe I was doing this before, but that is the only way I can duplicate the problem.

Much thanks.

TC
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