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raw_based_exposure_feedback [2021/02/04 04:18]
Audionut links
raw_based_exposure_feedback [2021/02/04 06:45]
Audionut more formatting
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   * [[#Histobar]]   * [[#Histobar]]
   * [[#Zebras]]   * [[#Zebras]]
-  * [[#Dual Zebras]]+  * [[#Dual Zebras|Dual ISO Zebras]]
   * [[#RAW vs JPG]]   * [[#RAW vs JPG]]
  
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 The spotmeter is a tool used to meter a particular area of the scene.  For instance, you may want to meter a particular area of your scene, as a highlight, a midtone, or whatever.  The raw based spotmeter in ML works in EV [[wp>Exposure_value|Exposure Value]] units, and represents the EV from saturation [[/glossary/#overexposure|(overexposure)]]. The spotmeter is a tool used to meter a particular area of the scene.  For instance, you may want to meter a particular area of your scene, as a highlight, a midtone, or whatever.  The raw based spotmeter in ML works in EV [[wp>Exposure_value|Exposure Value]] units, and represents the EV from saturation [[/glossary/#overexposure|(overexposure)]].
  
-Below is a teddy bear, showing the midtone patch metered for a midtone, checking the white level at this metering, and then after [[#ettr|Exposing to the Right]].+Below is a teddy bear, showing the midtone patch metered for a midtone, checking the white level at this metering, and then after [[/glossary/#ettr|Exposing to the Right]].
  
 {{ https://s1.postimg.cc/32j1k4ilj3/Spot_ETTR.jpg?200}} {{https://s1.postimg.cc/77emw8deq7/Spot_Midtone.jpg?200 }} {{ https://s1.postimg.cc/8l1609lw5r/Spot_Highlight.jpg?200  }} {{ https://s1.postimg.cc/32j1k4ilj3/Spot_ETTR.jpg?200}} {{https://s1.postimg.cc/77emw8deq7/Spot_Midtone.jpg?200 }} {{ https://s1.postimg.cc/8l1609lw5r/Spot_Highlight.jpg?200  }}
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 The histogram provides a graphical representation of the exposure of the entire scene. The histogram provides a graphical representation of the exposure of the entire scene.
-{{ https://s1.postimg.cc/60vbnmdcwf/Histogram.jpg?200}} 
  
 The colors in the histogram, represent the color channel in the camera (Red, Green, Blue). The colors in the histogram, represent the color channel in the camera (Red, Green, Blue).
-You will also notice, that ML displays Cyan, Magenta and Yellow.  If you look at the color chart below, you can see that Yellow falls in between Green and Red, and hence, Yellow represents data in both the Green and Red channels.  Cyan being the data from Green and Blue channels, and Magenta being the data from Blue and Red channels.  White indicates data from all color channels.+You will also notice, that ML displays Cyan, Magenta and Yellow.  If you look at the color chart below, you can see that Yellow falls in between Green and Red, and hence, Yellow represents data in both the Green and Red channels.  Cyan being the data from Green and Blue channels, and Magenta being the data from Blue and Red channels.  White indicates data from all color channels. [[http://upload.wikimedia.org/wikipedia/commons/3/3b/CIE1931xy_blank.svg|Color reference]]. 
 +{{https://s1.postimg.cc/60vbnmdcwf/Histogram.jpg?200 }}
  
 The white vertical lines at the rear of the histogram display, represent full stop EV.  So the very right hand side of the histogram represents overexposure.  The first line from the right hand side, represents 1 EV (a full stop) from overexposure, the next line is another 1 EV (2 EV total) from overexposure, and so on. The white vertical lines at the rear of the histogram display, represent full stop EV.  So the very right hand side of the histogram represents overexposure.  The first line from the right hand side, represents 1 EV (a full stop) from overexposure, the next line is another 1 EV (2 EV total) from overexposure, and so on.
- 
-{{ http://upload.wikimedia.org/wikipedia/commons/3/3b/CIE1931xy_blank.svg?200}} 
- 
  
 When the scene contains overexposure, the histogram will provide warnings. When the scene contains overexposure, the histogram will provide warnings.
  
-{{ https://s1.postimg.cc/1e9omxht9r/Histo_Over.jpg?200}}+{{https://s1.postimg.cc/1e9omxht9r/Histo_Over.jpg?200 }}
  
 The colored circles in the histogram, warn of overexposure in the color channel The colored circles in the histogram, warn of overexposure in the color channel
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-[hr] +== Histogram ETTR feedback ==
- +
-The histogram in ML also contains [url=http://en.wikipedia.org/wiki/Exposing_to_the_right]Exposure to the Right[/url] information.  This feedback show the user how far they can Expose to the Right before overexposing. +
- +
-[img width=300]https://s1.postimg.cc/4xiuykuycf/ETTR_hint.png[/img]+
  
-Take this scene metered with Canon Av mode. +{{ https://s1.postimg.cc/4xiuykuycf/ETTR_hint.png?200}} 
-[img width=400]https://s1.postimg.cc/5movwricfj/Under.jpg[/img]+The histogram in ML also contains [[/glossary/#ETTR|Exposure to the Right]] information.  This feedback shows the user how far they can Expose to the Right before [[/glossary/#overexposing]].
  
-Here we are being given feedback that suggests we can push the exposure 1.5 EV (stops) before overexposure+In the three images below, on the left we are being given feedback that suggests we can push the exposure 1.5 EV (stops) before reaching overexposurein the middle the scene has been exposed to the right, and on the right hand side, the scene has overexposure.
-And in the two images below, on the left hand side, the scene has been Exposed to the Right, and on the right hand side, the scene has been overexposed.+
  
-[img width=400]https://s1.postimg.cc/8z7lr4oeov/ETTR.jpg[/img] [img width=400]https://s1.postimg.cc/64exlcg2u7/Over.jpg[/img]+{{https://s1.postimg.cc/5movwricfj/Under.jpg?200 }} {{ https://s1.postimg.cc/64exlcg2u7/Over.jpg?200}} {{ https://s1.postimg.cc/8z7lr4oeov/ETTR.jpg?200 }}
  
-[color=red]Note:[/color]  Due to inconsistencies in the original firmware design, determining the correct overexposure point is extremely difficult.  You should be very wary when the histogram reads from -0.4EV through to (slight) overexposure.  There may be some slight overexposure when none is reported, or vice-versa, there may be no overexposure even though some has been reported.  If you know the true saturation value for your sensor at the shot settings, you may wish to use [url=https://builds.magiclantern.fm/modules.html#raw_diag]raw_diag[/url] if you like to nitpick.+Due to inconsistencies in the original firmware design, determining the correct overexposure point is extremely difficult.  You should be very wary when the histogram reads from -0.4EV through to (slight) overexposure.  There may be some slight overexposure when none is reported, or vice-versa, there may be no overexposure even though some has been reported.  If you know the true saturation value for your sensor at the shot settings, you may wish to use [[https://builds.magiclantern.fm/modules.html#raw_diag|raw_diag.mo]] if you like to nitpick.
  
 Otherwise, to be certain of no overexposure, target a ETTR hint > -0.4EV. Otherwise, to be certain of no overexposure, target a ETTR hint > -0.4EV.
  
-[url=http://www.magiclantern.fm/forum/index.php?topic=20579.msg192432#msg192432]Further discussion.[/url]+[[http://www.magiclantern.fm/forum/index.php?topic=20579.msg192432#msg192432|Further discussion]]
  
-[hr]+== Histogram Dynamic Range Feedback ==
  
 The histogram in ML also contains [url=http://en.wikipedia.org/wiki/Dynamic_range]Dynamic Range[/url] feedback.  This describes the ratio between the reported white level, and the [url=http://en.wikipedia.org/wiki/Noise_floor]Noise Floor[/url] of the camera, and is only very accurate when the image contains overexposed pixels. The histogram in ML also contains [url=http://en.wikipedia.org/wiki/Dynamic_range]Dynamic Range[/url] feedback.  This describes the ratio between the reported white level, and the [url=http://en.wikipedia.org/wiki/Noise_floor]Noise Floor[/url] of the camera, and is only very accurate when the image contains overexposed pixels.
raw_based_exposure_feedback.txt · Last modified: 2021/02/04 08:32 by Audionut