|RedCam CentralSite Admin
Joined: 14 Dec 2006
Location: Los Angeles
|Posted: Tue Mar 30, 2010 3:15 pm Post subject: Difference between Dynamic Range (DR) and Lattitude
Thought I'd post this clear and concise explaination of the difference between Dynamic Range and Lattitude as described by Graeme Nattress of RED:
"Lattitude is how much you can under or over expose a given scene and still have a usable picture. DR is the difference between the brightest and darkest detail you can record in an image. Lattitude is equal to recordable DR minus scene DR (the difference between the brightest and darkest detail in the scene to be recorded).
Lattitude varies per scene. DR is not scene dependent.
Cameras only have DR - they don't have latitude. It's the combination of scene and camera DR that leads to latitude.
Say you're shooting a typical scene of a "Macbeth chart" - which has a 5 stop range between the brightest chip and the darkest. Say your camera has a 13 stop DR. That means you've got 8 stops left - 8 stops of latitude. You can over expose the chart by 4 stops or under expose by 4 stops and still get all the detail in the chart. However, practical latitude will be less as when you try to exercise that latitude, the image will get noisier as it gets more under-exposed.
Now say your scene is a DSC CDM with cavi-black, giving you around 10 stop scene DR. Your latitude is now 3 stops, maybe less with your noise tolerance.
So latitude is utterly scene dependent, DR is utterly camera dependent."
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