A tool for chronophotography through video-postprocessing "timeslots" is a program that allows you to use normal video cameras (DV, HDV, anything) to be used as a scanning device. By using just a narrow slit out of the captured video, the working principle is comparable to normal desktop scanners, but with the benefit of better optics, portability and flexibility for experimental purposes. My first use of this software was the creation of surrealistic imagery for the
"timeslots" exhibition starting in June 2006 in Cologne. More
documentation about this project will be available soon. Basically, this software can be used comparable to the classic analog slitcam photography that is invoked for panoramas. There, the chemical film is transported against the rotating camera, so that the environment is "written down" as a panorama. But if you keep the camera still, while the film is moving, you get the changes of time within your slit projected in your resulting image. This is also the base of many other works by KHM artists like Sascha Blume or Irena Paskali, who have used a digital panorama camera by Spheron VR. Since you can set the width of the slit as you like, you can fine-tune it to reproduce objects, that are moving through the slits, with little distortion while the background gets repeated and thus wiped away - because it doesn't change fast, normally. The look of the resulting image is very dependent of your footage and your processing settings as well. After some experimentation it gets easier to anticipate the results. Rapid-prototypes taken with little digital cameras can help to find good pictures.
My intention in writing this software was to be able to use every motion camera technology from simple cellphone cameras to high-definition video to broaden the use of this expterimental technique and to be independent of expensive equipment like the Spheron camera. Furthermore, since it is a commandline program, it can be used efficiently through the powerful scripting techniques of shells like the bash (which is standard for most modern NIXes). Another design goal was to maximize processing performance which is useful for quickly adjusting parameters or generating motion imagery. The second is an application, which was not possible with still imagery approaches like the Spheron. The next release of timeslots will be dedicated to this application. Comparable but different approaches: "Querläufer" by Christian Keßler "Streak Photography" "Improvised Scanning Digital Camera" by Andrew Davidhazy
"Scanner Umbau" by Markus Keinath Read more to download and use the timeslots. Comments are welcome.
timeslots v1
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Copyright 2006, Ludwig Zeller
DOWNLOAD: timeslots1.zip
CONTACT:
ludwig( at )khm.de
COPYRIGHT:
timeslots is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
timeslots is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
I would be glad if you inform me about ideas and improvements in the code!
HISTORY:
This software is based on ideas presented in
stich.sh V 0.5 c KHM 16.3.2005
wsdrec V 1.1 c KHM 30.3.2000
abi_rec V 1.0 c IFNM 3.1.1991
REQUIREMENTS:
A contemporary UNIX derived operating system like Linux or OS X and an installation of ImageMagick.
FIRST RUN:
0. ImageMagick!
Before we begin to install timeslots, you have to install ImageMagick. This can be done by invoking the packet manager of your distribution (e.g. aptitude, yast or darwinports) or by downloading it from http://www.imagemagick.org.
1. Compile!
If you are not running on a i386 architecture, you have to compile the ddim.c for your CPU. ddim is the actual working horse of this program, since it is responsible for the copying of the slots. To improve efficiency, this is written in C. Many thanks to Martin Rumori for his support.
gcc -o timeslots timeslots.c
If you are running it on Intel Macs, please tell me if the included ddim build is running without any problems.
2. Install!
Make sure to add timeslots.sh and ddim into your program search path. This could be done by moving it to /bin, if you have root privileges. There are other ways to accomplish this, of course.
3. Prepare your footage!
timeslots only reads image sequences in BMP format. So you have to convert your video footage into a BMP sequence. This can be done by e.g. FinalCut and many other packages. A good choice is also ffmpeg, if your video is already cut and setup all nice and you just want to convert without editing. There is an OSX GUI version available named ffmpegx - haven't tried it yet.
Please mind that your sequence has to be enumerated properly.
Wrong: name99.bmp, name100.bmp,... Correct: name0099.bmp, name0100.bmp
It doesn't matter, how many numbers you use as your index, as long as it stays the same over the whole sequence (See the -0 option). You can use the little enumerator.sh script, that it is found in the bin folder, to batch rename your misnamed files. Try enumerator.sh -? for a little help.
4. Run!
You are ready for your first run. An initial command could look like this:
"timeslots.sh -v -a1 -b1000 -04 -f1 -s8 -w576 -y288 -o outputname inputwithoutindex" (e.g. "input" for "input0008")
This will read inputwithoutindex0001 to inputwithoutindex1000 and extract a 8 pixel wide slot starting at line 288. Both input and output paths are relative to the working directory, of course. So the output will be placed in the same folder - you could as well specify another folder for input and out like "-o outfolder/outname inputfolder/inoutname".
The output file will be named something like "inputwithoutindex-1-8-1-1000-288.jpg". This helps you, to distinguish the different output files.
There are other options available, that are not documented yet. Try timeslots.sh -? to see a list of available options.
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