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 +**Magic Lantern RAW based exposure feedback**
 +;#;
 +
 +
 +
 Magic Lantern contains a number of exposure feedback features, based from raw data.  This is very beneficial, as regular Canon exposure feedback is subject to picture style, and other JPG based processing. Magic Lantern contains a number of exposure feedback features, based from raw data.  This is very beneficial, as regular Canon exposure feedback is subject to picture style, and other JPG based processing.
  
-[hr]+{{ https://s1.postimg.cc/6ggsz6boun/Global_draw.png?200|}} 
 +These features can be found in the Overlay menu. See image ->
  
-These features can be found in the Overlay menu. 
  
-[img width=300]https://s1.postimg.cc/6ggsz6boun/Global_draw.png[/img] 
  
  
-They work in both Movie mode and Photo mode Live View, and in the Quick Image review.  +They work in both [[/glossary/#Movie mode]] and Photo mode [[/glossary/#Live View]], and in the [[/glossary/#Quick Image review]].  
  
 In Movie mode Live View, you must load one of the raw recording modules and have it activated for raw based exposure feedback to function. In Movie mode Live View, you must load one of the raw recording modules and have it activated for raw based exposure feedback to function.
 In Photo mode (Live View or not), picture quality must be set to raw in Canon menu, and in Photo mode Live View, ExpSim must be enabled. In Photo mode (Live View or not), picture quality must be set to raw in Canon menu, and in Photo mode Live View, ExpSim must be enabled.
  
-[iurl=#Spotmeter][b]Spotmeter[/b][/iurl] +  * [[#Spotmeter]] 
-[iurl=#Histogram][b]Histogram[/b][/iurl] +  * [[#Histogram]] 
-[iurl=#Histobar][b]Simplified Histobar[/b][/iurl] +  * [[#Histobar]] 
-[iurl=#Zebras][b]Zebras[/b][/iurl] +  * [[#Zebras]] 
-[iurl=#dualzebras][b]Dual ISO Zebras[/b][/iurl+  * [[#Dual Zebras|Dual ISO Zebras]] 
-[iurl=#JPG][b]RAW vs JPG[/b][/iurl]+  * [[#RAW vs JPG]]
  
-[hr]+\\ 
  
-[anchor=Spotmeter][color=green][size=14pt][u][b]Spotmeter[/b][/u][/size][/color][/anchor] 
  
-[img width=300]https://s1.postimg.cc/7jgia29vlr/Spotmeter.png[/img]+==== Spotmeter ====
  
-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 ([url=http://en.wikipedia.org/wiki/Exposure_value]Exposure Value[/url]) units, and represents the EV from saturation (overexposure).+{{ https://s1.postimg.cc/7jgia29vlr/Spotmeter.png?200}}
  
-Here is a teddy bearshowing the midtone patch metered for a midtone, checking the white level at this metering, and then Exposing to the Right. +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)]].
-[img width=300]https://s1.postimg.cc/77emw8deq7/Spot_Midtone.jpg[/img] [img width=300]https://s1.postimg.cc/8l1609lw5r/Spot_Highlight.jpg[/img[img width=300]https://s1.postimg.cc/32j1k4ilj3/Spot_ETTR.jpg[/img]+
  
-[hr]+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]].
  
-[anchor=Histogram][color=green][size=14pt][u][b]Histogram[/b][/u][/size][/color][/anchor]+{{ 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  }} 
 + 
 +\\  
 +\\  
 + 
 +==== Histogram ==== 
 + 
 +{{ https://s1.postimg.cc/59xhqkpsa7/Histogram.png?200}} 
  
-[img width=300]https://s1.postimg.cc/59xhqkpsa7/Histogram.png[/img] 
  
 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.
- 
-[img width=400]https://s1.postimg.cc/60vbnmdcwf/Histogram.jpg[/img] 
  
 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.
- 
-[img width=300]http://upload.wikimedia.org/wikipedia/commons/3/3b/CIE1931xy_blank.svg[/img] 
- 
  
 When the scene contains overexposure, the histogram will provide warnings. When the scene contains overexposure, the histogram will provide warnings.
  
-[img width=400]https://s1.postimg.cc/1e9omxht9r/Histo_Over.jpg[/img]+{{https://s1.postimg.cc/1e9omxht9r/Histo_Over.jpg?200 }}
  
-The colored circles in the histogram, warn of overexposure in the color channel.  Small circles show a very small amount of exposure, with the circles increasing in size.  When at least 1 % of the pixels of a channel are overexposed, the numbers inside these colored circles, describe the percentage of pixels that have been overexposed in that color channel.  In the above example. 1% of red pixels have been overexposed, 10% of green pixels and 2% of Blue pixels.+The colored circles in the histogram, warn of overexposure in the color channel 
 +((This information is derived from the downsized Live View stream.  So the percentages reported, may not be an //extremely// accurate representation of the actual percentage, but provides useful information nonetheless.)).  Small circles show a very small amount of exposure, with the circles increasing in size.  When at least 1 % of the pixels of a channel are overexposed, the numbers inside these colored circles, describe the percentage of pixels that have been overexposed in that color channel.  In the above example. 1% of red pixels have been overexposed, 10% of green pixels and 2% of Blue pixels.\\  
 +\\  
 +\\  
 +\\ 
  
-[color=red]Note:[/color]  This information is derived from the downsized Live View stream.  So the percentages reported, may not be an [i]extremely[/i] accurate representation of the actual percentage, but provides useful information nonetheless. 
  
-[hr] 
  
-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.+== Histogram ETTR feedback ==
  
-[img width=300]https://s1.postimg.cc/4xiuykuycf/ETTR_hint.png[/img]+{{ https://s1.postimg.cc/4xiuykuycf/ETTR_hint.png?200}} 
 +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]].
  
-Take this scene metered with Canon Av mode. +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 overexposure, in the middle the scene has been exposed to the right, and on the right hand side, the scene has overexposure.
-[img width=400]https://s1.postimg.cc/5movwricfj/Under.jpg[/img]+
  
-Here we are being given feedback that suggests we can push the exposure 1.5 EV (stops) before overexposure. +{{https://s1.postimg.cc/5movwricfj/Under.jpg?200 }} {{ https://s1.postimg.cc/64exlcg2u7/Over.jpg?200}} {{ https://s1.postimg.cc/8z7lr4oeov/ETTR.jpg?200 }}
-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] +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.
- +
-[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.+
  
 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 [[wp>Dynamic_range|Dynamic Range]] feedback.  This describes the ratio between the reported white level, and the [[wp>Noise_floor|Noise Floor]] of the camera, and is only very accurate when the image contains overexposed pixels.
  
-[img width=300]https://s1.postimg.cc/5f8wn5utwv/DR_hint.png[/img]+{{ https://s1.postimg.cc/5f8wn5utwv/DR_hint.png?200}} {{https://s1.postimg.cc/67ls4wdd33/Histo_DR.jpg?200 }}
  
-[img width=400]https://s1.postimg.cc/67ls4wdd33/Histo_DR.jpg[/img]+Note The brown area in the rear of the histogram represents this noise floor. 
 +\\  
 +\\  
 +\\  
 +\\  
 +\\  
 +\\  
 +\\  
 +\\ 
  
-Note:  The brown area in the histogram represents this noise floor. 
  
-[hr] +===Simplified Histobar ====
- +
-[anchor=Histobar][color=green][u][size=14pt][b]Simplified Histobar[/b][/size][/u][/color][/anchor]+
  
 +{{ https://s1.postimg.cc/9gxnfpuab3/Histobar.png?200}}
 For LiveView work, there is also the Simplified Histobar. For LiveView work, there is also the Simplified Histobar.
  
-[img width=300]https://s1.postimg.cc/9gxnfpuab3/Histobar.png[/img] 
  
-The Histobar is shown here at the top left of the liveview screen. 
  
-[img width=400]https://s1.postimg.cc/8s4dvpcbwv/Histobar1.png[/img]+The Histobar is shown here at the top left of the liveview screen. 
 +{{https://s1.postimg.cc/8s4dvpcbwv/Histobar1.png?200 }}
  
 Red indicates overexposure, blue indicates extreme underexposure, and the yellow bar represents the midpoint. Red indicates overexposure, blue indicates extreme underexposure, and the yellow bar represents the midpoint.
 The blue bar increases in size with increasing underexposure.  So the image above shows a small amount of the scene is extremely underexposed, and a full bar would indicate a large amount of the scene is extremely underexposed. The blue bar increases in size with increasing underexposure.  So the image above shows a small amount of the scene is extremely underexposed, and a full bar would indicate a large amount of the scene is extremely underexposed.
  
-The midtone point is the median of the scene.  For further information, see [url=http://www.magiclantern.fm/forum/index.php?topic=8539.msg80044#msg80044]this post[/url] by a1ex.+The midtone point is the median of the scene.  For further information, see [[ml>forum/index.php?topic=8539.msg80044#msg80044|this post]] by a1ex.
  
-[hr] 
  
-[anchor=Zebras][color=green][u][size=14pt][b]Zebras[/b][/size][/u][/color][/anchor] 
  
-[img width=300]https://s1.postimg.cc/6ggsz6eh5r/Zebras.png[/img]+==== Zebras ==== 
 + 
 +{{ https://s1.postimg.cc/6ggsz6eh5r/Zebras.png?200}}
  
 Zebras provide a graphical overlay of the areas in the scene which are overexposed, and underexposed. Zebras provide a graphical overlay of the areas in the scene which are overexposed, and underexposed.
  
-[img width=360]https://s1.postimg.cc/1htaknr6en/Zebra1.png[/img] [img]https://s1.postimg.cc/2dd0lxt9zz/97pwi.gif[/img]+{{https://s1.postimg.cc/1htaknr6en/Zebra1.png?200 }} {{https://s1.postimg.cc/2dd0lxt9zz/97pwi.gif?200 }} 
 +\\  
 +\\  
 +\\  
 +\\  
 +\\  
 +\\  
 +\\ 
  
-And a scene showing zebras/histogram, with overexposure, and underexposure.+{{ https://s1.postimg.cc/96atmkc24v/Histo_Zebras.jpg?200}} 
 +And a scene showing zebras/histogram, with overexposure, and underexposure. -> See image
  
-[img width=400]https://s1.postimg.cc/96atmkc24v/Histo_Zebras.jpg[/img] 
  
 As with the histogram, the color displayed by the zebras, represent the color channel in the camera that is overexposed.  Again, a Cyan reading is describing overexposure in both the Green, and the Blue channels, Yellow describing both Green and Red channels, and Magenta describing both Red and Blue channels. As with the histogram, the color displayed by the zebras, represent the color channel in the camera that is overexposed.  Again, a Cyan reading is describing overexposure in both the Green, and the Blue channels, Yellow describing both Green and Red channels, and Magenta describing both Red and Blue channels.
 +\\ 
 +\\ 
 +\\ 
 +\\ 
  
-Unlike the histogram, black describes overexposure in all color channels, and white describes underexposure.  [s]This underexposure point describes any data that is within 1 EV of the camera noise floor[/s]. +{{ https://s1.postimg.cc/9b9h4ytg7j/Zebra_under.png?200}} 
- +== Raw Zebra Underexposure== 
- +This allows you to choose at what exposure the [[/glossary/#underexposure]] zebras will be displayed.  0 EV means that the zebras will be displayed where the amount of [[/glossary/#noise]] in the image, is equal to the amount of signal in the image (the [[/glossary/#SNR|noise floor]]).  
-Update:  dmilligan added some underexposure adjustment to the zebras. +
-[img width=400]https://s1.postimg.cc/9b9h4ytg7j/Zebra_under.png[/img] +
- +
-This allows you to choose at what exposure the underexposure zebras will be displayed.  0 EV means that the zebras will be displayed where the amount of noise in the image, is equal to the amount of signal in the image (the noise floor).  +
 A general consensus amongst photographers, is that the limit for acceptable amount of noise in images, is 2 EV above this noise floor. A general consensus amongst photographers, is that the limit for acceptable amount of noise in images, is 2 EV above this noise floor.
  
raw_based_exposure_feedback.1612406770.txt.gz · Last modified: 2021/02/04 03:46 by Audionut