darktable/lua-scripts-w-api
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

fujifilm-dynamic-range: better exiftool parsing & comments

Browse Source 
Get tab-delimited output from exiftool without rounding.  Add comments
to explain the choice of tags being read and tool to read them.
This commit is contained in:
Dan Torop
2021-01-06 10:11:59 -05:00
parent b08d7f27d2
commit 952b8b2eb2
1 changed files with 31 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
contrib/fujifilm_dynamic_range.lua
View File

@@ -28,6 +28,33 @@ Dependencies:
Based upon fujifilm_ratings by Ben Mendis
The relevant tag is RawExposureBias (0x9650). This appears to
represent the shift in EV for the chosen DR setting (whether manual or
automatic). Note that even at 100DR ("standard") there is an EV shift:
100 DR -> -0.72 EV
200 DR -> -1.72 EV
400 DR -> -2.72 EV
The ideal would be to use exiv2 to read this tag, as this is the same
code which darktable import uses. Unfortunately, exiv2 as of v0.27.3
can't read this tag. As it is encoded as a 4-byte ratio of two signed
shorts -- a novel data type -- it will require some attention to fix
this.
There is an exiv2-readable DevelopmentDynamicRange tag which maps to
RawExposureBias as above. DevelopmentDynamicRange is only present
when tag DynamicRangeSetting (0x1402) is Manual/Raw (0x0001). When it
is Auto (0x0000), the equivalent data is tag AutoDynamicRange
(0x140b). But exiv2 currently can't read that tag either.
Hence for now this code uses exiftool to read RawExposureBias, as a
more general solution. As exiftool is approx. 10x slower than exiv2
(Perl vs. C++), this may slow large imports.
These tags have been checked on a Fujifilm X100S and X100V. Other
cameras may behave in other ways.
--]]
local dt = require "darktable"
@@ -44,25 +71,25 @@ local function _(msgid)
end
local function detect_dynamic_range(event, image)
-- exiftool knows about the RawExposureBias tag, unlike exiv2, but it is also 10x slower
if not df.check_if_bin_exists("exiftool") then
dt.print_error(_("exiftool not found"))
return
end
local RAF_filename = df.sanitize_filename(tostring(image))
local command = "exiftool -RawExposureBias " .. RAF_filename
-- without -n flag, exiftool will round to the nearest tenth
local command = "exiftool -RawExposureBias -n -t " .. RAF_filename
dt.print_error(command)
output = io.popen(command)
local raf_result = output:read("*all")
output:close()
if string.len(raf_result) > 0 then
raf_result = string.gsub(raf_result, "^Raw Exposure Bias.-([%d%.%-]+)", "%1")
raf_result = string.match(raf_result, "\t(.*)")
if image.exif_exposure_bias ~= image.exif_exposure_bias then
-- is NAN (this is unlikely as RAFs should have ExposureBiasValue set)
image.exif_exposure_bias = 0
end
-- this should be auto-applied if plugins/darkroom/workflow is scene-referred
-- FIXME: scene-referred workflow pushes exposure up 0.5 EV, but DR100 pushes up 0.7 EV -- should reduce this by 0.5 EV?
-- note that scene-referred workflow exposure preset also pushes exposure up by 0.5 EV
image.exif_exposure_bias = image.exif_exposure_bias + tonumber(raf_result)
dt.print_error(_("Using RAF exposure bias: ") .. tostring(raf_result))
end