62 lines
1.7 KiB
Markdown
62 lines
1.7 KiB
Markdown
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---
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title: fujifilm_dynamic_range
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id: fujifilm_dynamic_range
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weight: 105
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draft: false
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author: "people"
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---
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## Name
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fujifilm_dynamic_range.lua -
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## Description
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Support for adjusting darktable exposure by Fujifilm raw exposure
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bias. This corrects for a DR100/DR200/DR400 "dynamic range" setting.
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Based upon fujifilm_ratings by Ben Mendis
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The relevant tag is RawExposureBias \(0x9650\). This appears to
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represent the shift in EV for the chosen DR setting \(whether manual or
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automatic\). Note that even at 100DR \("standard"\) there is an EV shift:
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100 DR -> -0.72 EV
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200 DR -> -1.72 EV
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400 DR -> -2.72 EV
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The ideal would be to use exiv2 to read this tag, as this is the same
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code which darktable import uses. Unfortunately, exiv2 as of v0.27.3
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can't read this tag. As it is encoded as a 4-byte ratio of two signed
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shorts -- a novel data type -- it will require some attention to fix
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this.
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There is an exiv2-readable DevelopmentDynamicRange tag which maps to
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RawExposureBias as above. DevelopmentDynamicRange is only present
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when tag DynamicRangeSetting \(0x1402\) is Manual/Raw \(0x0001\). When it
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is Auto \(0x0000\), the equivalent data is tag AutoDynamicRange
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\(0x140b\). But exiv2 currently can't read that tag either.
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Hence for now this code uses exiftool to read RawExposureBias, as a
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more general solution. As exiftool is approx. 10x slower than exiv2
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\(Perl vs. C++\), this may slow large imports.
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These tags have been checked on a Fujifilm X100S and X100V. Other
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cameras may behave in other ways.
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## Usage
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Start this script from script manager
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## Additional Software Required
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exiftool (https://www.sno.phy.queensu.ca/~phil/exiftool/)
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## Limitations
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## Author
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Dan Torop <dant@pnym.net>
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## Change Log
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