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Canon vs CHDK histograms

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Offline reyalp

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Re: Canon vs CHDK histograms
« Reply #20 on: 10 / May / 2021, 12:27:34 »
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Quote from: Ant on 10 / May / 2021, 03:28:13
Probably this problem is caused by incorrect viewport buffer dimensions. Have you tried earlier builds?
No, the histogram code does not correctly handle some viewport sizes, even if the viewport dimensions are correct. Of course, there could be additional problems on top of that.
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Offline reyalp

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Re: Canon vs CHDK histograms
« Reply #21 on: 10 / May / 2021, 12:51:49 »
Quote from: pigeonhill on 10 / May / 2021, 03:42:43
Just looking at 3:2 format, I would say the CHDK histogram is about 1-2 stops different to the Canon.
Thanks.

Do you see the random jumps and under / over exposure warning dots?

Quote
For example, a histo peak on the Canon at -3eV from highlights, will be at about -1eV on CHDK.

Update

The difference scales as you shift exposure.
OK, from the screen grab, that definitely seems like a different problem.

Does the same happen if you use Canon "Brightness histogram" and CHDK Y?
Can you take screenshots at 0 shift and +1?

If you are able to use chdkptp, taking a "quick dump" from the live view in each setting would be ideal, since that would allow me to see the actual viewport values.
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Offline pigeonhill

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Re: Canon vs CHDK histograms
« Reply #22 on: 10 / May / 2021, 13:24:52 »
@reyalp

Have never touched CHDKptp, sorry.

Took a few screen shots at different shutters, 1 eV apart. Set Y histo.

Warning dots seem to stay on, until they go.
« Last Edit: 10 / May / 2021, 13:30:31 by pigeonhill »
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Offline pigeonhill

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Re: Canon vs CHDK histograms
« Reply #23 on: 10 / May / 2021, 13:25:32 »
More images
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Offline reyalp

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Re: Canon vs CHDK histograms
« Reply #24 on: 10 / May / 2021, 13:30:24 »
If you can compare the Canon "brightness" histogram, rather than RGB, that would be helpful for me.
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Offline pigeonhill

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Re: Canon vs CHDK histograms
« Reply #25 on: 10 / May / 2021, 13:58:39 »
Not sure I can do that. The luminance canon histo only shows in playback, not LV.
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Offline Caefix

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Re: Canon vs CHDK histograms
« Reply #26 on: 10 / May / 2021, 14:18:05 »
Quote from: pigeonhill on 10 / May / 2021, 13:24:52
@reyalp

Have never touched CHDKptp, sorry.

Warning dots seem to stay on, until they go.
:P ... shoudn´t explode...
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Offline reyalp

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Re: Canon vs CHDK histograms
« Reply #27 on: 10 / May / 2021, 14:35:17 »
Quote from: pigeonhill on 10 / May / 2021, 13:58:39
Not sure I can do that. The luminance canon histo only shows in playback, not LV.
The manual section "Customizing Controls and Display - Customizing displayed data" (page 87 in the version I have) appears to suggest you can.
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Offline pigeonhill

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Re: Canon vs CHDK histograms
« Reply #28 on: 10 / May / 2021, 14:53:37 »
 :o

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Offline reyalp

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Re: Canon vs CHDK histograms
« Reply #29 on: 10 / May / 2021, 16:01:50 »
 :blink:

Just to be sure, CHDK histogram is still in "linear" not "log"?
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