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Latitude and dynamic range


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#1 Matt Rosen

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Posted 30 December 2008 - 01:00 AM

I hear these terms thrown around a lot, but I've yet to get a good answer from anyone about how the meanings of these terms are different. None of my professors seem to know.


Here's my understanding. Please corroborate or correct it:

Latitude refers to the number of stops a given film or digital medium can record while still retaining detail. Anything outside that latitude will be either blown out or completely black.

Dynamic range refers to how digital media record information per pixel, so a 16 bit will have 16 levels of brightness between white and black (it gets more complicated when you factor color into the equation). The greater the dynamic range of a camera, the smoother its brights will roll into its darks.


Please tell me if I'm wrong.
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#2 David Mullen ASC

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Posted 30 December 2008 - 01:14 AM

Dynamic range is the range of exposure information that can be captured. Latitude is narrower -- it refers to the ability to make corrections to misexposed footage without unwanted or unacceptable artifacts. For example, you may be able to correct footage that is three stops overexposed and get an acceptable picture of "normal" brightness, but the dynamic range may include information that is five stops overexposed. But that doesn't mean you have the latitude to overexpose by five stops.
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#3 Matt Rosen

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Posted 30 December 2008 - 01:37 AM

Okay, so then dynamic range is the range from the brightest bright to the blackest black, and latitude is the range within that which contains enough detail to be corrected.
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#4 DJ Joofa

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Posted 30 December 2008 - 03:28 AM

It is misleading to consider dynamic range and latitude on the same medium if the scene illumination was such that more or less full range available on the negative has been utilized. The fact remains that print film typically has a smaller range than the one captured on the negative, for various reasons. Hence, to select which portion of the negative range should be developed into the range of the print film some portions of the negative information is either discarded or crammed into the smaller range of the print film. This gives leverage to the cinematographer since they can under or overexpose on the larger range of the negative knowing that full range will not be displayed and a portion can always be extracted and then moved accordingly to compensate for under/over exposure.

Think of latitude as an output side parameter (portion of negative that goes to print film) and dynamic range as an input side parameter (full range as recorded on the negative).

Therefore you have the following equation:

Dynamic range = latitude (portion that you select as viewable) + extra information that says on negative
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