Find out the contrast level - Script Writing - CHDK Forum
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Find out the contrast level

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Offline toby

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Find out the contrast level
« on: 24 / November / 2008, 03:02:28 »
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Hi,
is there a way or a command, where I can find out the level of contrast while not doing any zooming, shutter or focusing actions?
Greetz Tobi
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Offline dzsemx

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Re: Find out the contrast level
« Reply #1 on: 24 / November / 2008, 03:06:37 »
there is no function/command yet for such thing, but anybody can write and send the patch to the developers
« Last Edit: 24 / November / 2008, 03:12:11 by dzsemx »
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Offline fe50

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Re: Find out the contrast level
« Reply #2 on: 24 / November / 2008, 04:13:07 »
Quote from: toby on 24 / November / 2008, 03:02:28
is there a way or a command, where I can find out the level of contrast while not doing any zooming, shutter or focusing actions?

Try the get_histo_range,
more informations can be found in this thread: Timelapse with variable shutter speed (the name of this command has changed while development, the wikia info is up to date).
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Offline fbonomi

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Re: Find out the contrast level
« Reply #3 on: 24 / November / 2008, 04:21:07 »
toby, the get_histo_range might do what you want but they are quite different from what you are asking (getting the contrast level without focusing or shutter action)

At the VERY contrary, those commands get information about the histogram of the last image that was shot (i.e. after you have focused, meterd, shot etc.etc.)

What you need requires reading the live preview buffer and operating on that.

The giet_histo_range function operates on the RAW buffer; I have made it like this because I needed to get info about very dark scenes, and the live preview screen was completely black, while the RAW buffer (with a long enough exposure) would contain an image.

You should explain better what you want to achieve, I think that you could get some result playing with the motion detect routines, that work by dividing the live preview in little squares and monitoring changes of brightness within each single square.

Would that help?
« Last Edit: 24 / November / 2008, 07:03:42 by fbonomi »
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Offline fe50

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Re: Find out the contrast level
« Reply #4 on: 24 / November / 2008, 05:49:41 »
@fbonomi
One of your great , high specialised contributions  8)

I've updated the wikia: get_histo_range, can you pls. check whether i got all the infos right there ? thx.
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Offline fbonomi

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Re: Find out the contrast level
« Reply #5 on: 24 / November / 2008, 06:52:04 »
fe50, something odd is happening at the Wikia... shown text is very different from what I see while editing.

will try again later

EDIT: done, we were working togehter :-)
« Last Edit: 24 / November / 2008, 06:57:53 by fbonomi »
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Offline toby

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Re: Find out the contrast level
« Reply #6 on: 24 / November / 2008, 07:29:10 »
Hello, thx for your replys.
I need that contrastlevel, the AF is working with ( it need to be the fastest).
Is there such a command?
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