Previous tutorials: Recording material for chrono-photo and Preparing video material.
Next tutorial: Creating chrono-videos.
This tutorial explains how to use chrono-photo to create a chronophotography from an image sequence.
We assume that you have such an image sequence ready, e.g. obtained by following the tutorials linked above.
File extensions are for Windows. On Linux or Mac OSX, they need to be adapted accordingly.
Particularly Windows batch files (.bat) need to be replaces by Unix shell scripts (.sh).
See the Command line options documentation file for detailed explanation of all available options.
Content
For this tutorial, we assume the following structure for your working directory:
root/
├── images/
│ ├── image-0000.jpg
│ ├── image-0001.jpg
│ └── ...
├── output/
└── chrono-photo.exe
Note: You can copy the
chrono-photoexecutable anywhere for use with convenient paths. No further files from the installation directory are required.
The above structure is not required, we assume it just for convenient command line usage. E.g., input images and output folder can be in completely different locations.
To print help for chrono-photo, run
chrono-photo -h
or, for more comprehensive help texts
chrono-photo --help
We start by processing the images using standard parameters.
In root/, create a file example-01.bat and copy the following lines there:
chrono-photo ^
--pattern "images/*.jpg" ^
--output output/out.jpg
Here, we only specify the search pattern for input files, as well as the output file path.
Note: The ^ at the end of each line is required for breaking commands into multiple lines (at least on Windows).
Run the file from directory root/:
C:\...\root>example-01
For large projects with a lot of input images, it is recommended to start with the faster simple algorithm
by adding --mode darker or --mode lighter.
Use the former if the moving object is darker than the background, and the latter if it is brighter.
In many cases where the background is relatively homogeneous (e.g. sky), and the moving objects can be easily identified by brightness, this much faster algorithm yields already sufficient results.
Additionally, in this example we enable debug output:
chrono-photo ^
--pattern "images/*.jpg" ^
--output output/out.jpg ^
--mode darker ^
--debug
This command should complete in approx. 1/10th of the time required for the first example.
We return to the default algorithm by using --mode outlier, or just omitting --mode.
Further, we add a few more options:
chrono-photo ^
--pattern "images/*.jpg" ^
--output output/out.jpg ^
--output-blend output/out-blend.jpg ^
--mode outlier ^
--threshold abs/0.05/0.2 ^
--background random ^
--outlier extreme ^
--debug
Here, --output-blend creates a debug image showing the “algorithm’s view” of the images, in greyscale.
The next four option specify the algorithm and is’t details: We want to use the outlier algorithm, with an “absolute” threshold range (actually, it is relative to total color range 0 - 255). Selection between background pixels will be done randomly, while the most extreme outlier is selected in case outliers are found.
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