Readme for logctool

Introduction

logctool a set of utilities for processing logc encoded images. Test and verification data, including a step chart and color checker grid, can be generated for color space evaluation and testing.

Examples of stepchart and colorchecker using --transform sRGB for viewing.

Usage

Print logctool help message with flag --help.

logctool -- a set of utilities for processing logc encoded images

Usage: logctool [options] filename...

General flags:
    --help                           Print help message
    -v                               Verbose status messages
    --transforms                     List all transforms
    --ei EI                          LogC exposure index
    --dataformat DATAFORMAT          LogC format (default: float, uint8, uint10, uint16 and uint32)
    --transform TRANSFORM            LUT transform
Output flags:
    --outputtype OUTTYPE             Output type (default: stepchart, colorchecker)
    --outputfilename OUTFILENAME     Output filename of log steps
    --outputwidth WIDTH              Output width of log steps
    --outputheight HEIGHT            Output height of log steps
    --outputlinear                   Output linear steps
    --outputnolabels                 Output no labels
    --outputfalsecolorcubefile FILE  Optional output false color cube (lut) file
    --outputstopscubefile FILE       Optional output stops cube (lut) file

Generate LogC stepchart in OpenEXR float

./logcotol
-v
--outputwidth 2048
--outputheight 1024
--dataformat float
--outputtype stepchart
--outpitfilename /Volumes/Build/github/test/logctool_LogC3.exr

Generate LogC colorchecker in DPX 10-bit

./logcotol
-v
--outputwidth 2048
--outputheight 1024
--dataformat uin10
--outputtype colorchecker
--outputfilename /Volumes/Build/github/test/logctool_LogC3.exr

Generate Conversion LUTs in Davinci Resolve

./logcotol
-v
--outputwidth 2048
--outputheight 1024
--dataformat float
--outputfilename /Volumes/Build/github/test/logctool_LogC3.exr
--outputstopscubefile /Volumes/Build/github/test/logctool_LogC3_out.cube

Building

The logctool app can be built both from commandline or using optional Xcode -GXcode.

mkdir build
cd build
cmake .. -DCMAKE_MODULE_PATH=<path>/logctool/modules -DCMAKE_INSTALL_PREFIX=<path> -DCMAKE_PREFIX_PATH=<path> -GXcode
cmake --build . --config Release -j 8

Example using 3rdparty on arm64

mkdir build
cd build
cmake ..
cmake .. -DCMAKE_INSTALL_PREFIX=<path>/3rdparty/build/macosx/arm64.debug -DCMAKE_INSTALL_PREFIX=<path>/3rdparty/build/macosx/arm64.debug -DCMAKE_CXX_FLAGS="-I<path>/3rdparty/build/macosx/arm64.debug/include/eigen3" -DBUILD_SHARED_LIBS=TRUE -GXcode

Packaging

The macdeploy.sh script will deploy mac bundle to dmg including dependencies.

./macdeploy.sh -e <path>/logctool -d <path> -p <path>

Dependencies

Project	Description
OpenImageIO	OpenImageIO project @ Github
OpenColorIO	OpenColorIO project @ Github
OpenEXR	OpenEXR project @ Github
3rdparty	3rdparty project containing all dependencies @ Github

Limitations

Cube LUTs are limited in their precision therefore does not handle the toe of the curve very well.

Project

• GitHub page
  https://github.com/mikaelsundell/logctool
• Issues
  https://github.com/mikaelsundell/logctool/issues

Resources

• ALEXA Log C Curve
  https://github.com/mikaelsundell/utilities/blob/master/whitepapers/arri/11-06-30_Alexa_LogC_Curve.pdf

Copyright

• Arri LogC
  Copyright © 2023 ARRI AG. All rights reserved.

• X-Rite ColorChecker
  Copyright © 2009, X-Rite Incorporated. All rights reserved.

• Roboto font
  https://fonts.google.com/specimen/Roboto
  Designed by Christian Robertson