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Log Exposure vs Linear Exposure


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#1 Ashim

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Posted 09 October 2006 - 11:02 AM

Could anyone kindly give me a detailed explanation on the differences between Log Exposure vs.
Linear Exposure and the way it affects Image processing.
Any help shall be valued.
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#2 Mike Brennan

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Posted 09 October 2006 - 03:20 PM

Could anyone kindly give me a detailed explanation on the differences between Log Exposure vs.
Linear Exposure and the way it affects Image processing.
Any help shall be valued.


Do you mean exposing for log vs Linear
or
What is the difference between log and lin in a post environment?



Mike Brennan
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#3 Ashim

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Posted 10 October 2006 - 12:50 AM

Do you mean exposing for log vs Linear
or
What is the difference between log and lin in a post environment?
Mike Brennan



In the Post, where a commonly used file format for film scans, the Cineon or DPX format, uses 10 bits per channel, which equals 1024 levels, and linearly encodes the densities of the negative above base.
Now I fail to understand the latter part of the above statement ( and Linearly encodes the densities...).

I'd also like to know what does it mean to say that the Viper Filmsteream camera delivers an RGB 4:4:4
10 bit LOG output uncompromised by electronic camera processing.
Again the query is directed toward the Log output.

I underastand that film is a Log-Log medium(Log exposure vs. log density).
But what aout the digital cameras. they seem to be operating in both.

What is exposing for Log vs. Linear??
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#4 Matt Sandstrom

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Posted 15 October 2006 - 08:37 AM

I fail to understand the latter part of the above statement ( and Linearly encodes the densities...).

linear means that double the density means double the value. log means that double density means that the value increases by one. but i guess you knew that. i believe that ccd's are linear so if you record light, which is a log entity since it requires a doubling to get a linear increase in brightness, you get a log signal. the dsp converts this to a linear scale using a gamma of your choice.

/matt
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