Adjusting parallax in MPO stereo images

MPO stereo images, that were taken in example using Fujifilm FinePix Real 3D Cameras contain a field parallax in their exif data. The parallax value can be used by stereoscopic viewers like my stereoscopic image viewer SIV to adjust the 3D effect. By manipulating this value one can can customize the strength of the pop out effect and reduce the ghosting effect. This may lead to a more pleasuring viewing experience.

The parallax value can easily be displayed using exiftool:

exiftool -ee -Parallax DSCF0045.MPO

If you want to set the parallax value of an image, this is not that easy, since the value is stored in the exif data of the second embedded jpeg file in the MPO, which is not directly writable with exiftool. However one can find out the beginning of the second file with exiftool, extract the image and then set the parallax value. Afterwards on can put all together again using dd. Doing this manually is a quite awful task, so I wrote a little script for automating it:


#$1: MPO File $2: Parallax value

MPSTART=`exiftool -b -MPImageStart $1`
echo Multipart Image 2 begins at: $MPSTART
cp -a $1 $1.orig
exiftool $1.orig -mpimage2 -b | exiftool  -b -Parallax=$2 – \
| dd conv=notrunc bs=64 seek=$MPSTART of=$1

Use it at the command line as follows: [MPO-File] [new parallax value]

in example: DSCF0045.MPO 1.25

For determining the value that matches the visual requirements of your image you may use the parallax adjustment function of SIV (+/- key) and use the value on the OSD and printed out in the console. Perhaps some day I will add the functionality, to directly write the new parallax value to the MPO file, to SIV. However the setparallax script at least gives us the possibility to write the parallax value until then.



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Improved OpenSceneGraph-2.8.3 ebuild

The current OpenSceneGraph ebuild in the Gentoo Portage tree does not install the OpenSceneGraph sample data set.  These  files include some sample models, fonts, bitmaps etc. used in the OpenSceneGraph examples and other applications.  This is a problem for applications relying on the files to be available. In example my stereoscopic image viewer SIV relies on having the OpenSceneGraph sample dataset installed and fails to load the arial font from the dataset with the following error:

Warning: font file “fonts/arial.ttf” not found.

Here is my modified ebuild resolving this issue: OpenSceneGraph-2.8.3.tar.gz (1111)

Download the modified ebuild and extract the archive into /usr/local/portage. Be sure to include the following line in your /etc/make.conf:


If you want to use OpenSceneGraph with ffmpeg support, download the patch from and copy it to /etc/portage/patches/dev-games/openscenegraph-2.8.3/ as described there, to compile with ffmpeg-0.6. Otherwise the emerge will fail with:

error: cannot allocate an object of abstract type

Now you can set the examples USE-Flag and emerge openscenegraph to get the example dataset.

If you have got flightgear installed, reinstall simgear afterwards,  like the ebuild requests you to do:

emerge -1 dev-games/simgear

Depending on if you were upgrading or just reinstalling with the new ebuild it may be necessary to run revdep-rebuild to resolve issues with broken libraries. Hopefully the next ebuild in the portage tree will  include the sample data set.

Wxwidgets support seems to be broken with the current version. When using the wxwidgets USE-Flag Openscenegraph fails to compile with, so include

=dev-games/openscenegraph-3.0.1 -wxwidgets

in your /etc/portage/package.use if you have enabled wxwidgets in your make.conf.

best regards



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New version of SIV coming soon

I just fixed some bugs and implemented a slideshow mode in SIV, the viewer for stereoscopic jps  images, I published in  SIV – a stereoscopic jps viewer for Linux.  As I wrote before in  VR920 headtracking driver for Linux I want to extend the viewer using the tracking data from the VR920 HMD, so one can look around the scene by turning his head. Once this work is done you can enjoy a new experience in 3D.  So expect the download of a newer version of SIV to appear soon on

In the meanwhile you may want to share your experiences with the viewer. What do you like the viewer for? What do you think should be improved?

Stay tuned for updates 😉


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SIV – a stereoscopic jps viewer for Linux

As promised in JPS-viewer for linux, here comes the very first release of  SIV, the first available  Stereoscopic  Image Viewer for Linux supporting quad buffered stereo. Well this is not 100% correct, since it is build upon OpenSceneGraph it is somewhat platform independant and schould compile well on windows, mac and unix platforms. However, I only tried with linux since there are enough alternatives available for most other platforms.

SIV is  capable of displaying jps stereo images in different stereo modes. I tried it in fullscreen/windowed mode with anaglyphic and quad buffered stereo mode. Different output devices I tested were my Vuzix VR920 and relevator shutter glasses  on Nvidia Quadro FX 350M and FX 3400. It still lacks some convenience functions like a diashow mode.

Screenshot of the viewer as window in anaglyphic mode:


A note about the name SIV, SIV stands for Stereoscopic  Image Viewer, but as I found out Siv is also the name of the wife of the god Thor in the norse mythology. See: Wikipedia: Sif and Behindthename: Siv. Sif and Siv are the same name, both writings are possible. Once I found out this, I thought that’s a cool name for this piece of work.


./siv [options] jpsfile(s)
–CullDrawThreadPerContext                 Select CullDrawThreadPerContext
threading model for viewer.
–CullThreadPerCameraDrawThreadPerContext  Select
ntext threading model for viewer.
–DrawThreadPerContext                     Select DrawThreadPerContext
threading model for viewer.
–SingleThreaded                           Select SingleThreaded threading
model for viewer.
–accum-rgb                                Request a rgb accumulator buffer
–accum-rgba                               Request a rgb accumulator buffer
–cc                                       Request use of compile contexts and
–clear-color <color>                      Set the background color of the
viewer in the form “r,g,b[,a]”.
–display <type>                           MONITOR | POWERWALL |
–rgba                                     Request a RGBA color buffer visual
–samples <num>                            Request a multisample visual
–screen <num>                             Set the screen to use when multiple
screens are present.
–serialize-draw <mode>                    OFF | ON – set the serialization of
draw dispatch
–stencil                                  Request a stencil buffer visual
–stereo                                   Use default stereo mode which is
ANAGLYPHIC if not overriden by
environmental variable
–stereo <mode>                            ANAGLYPHIC | QUAD_BUFFER |
–window <x y w h>                         Set the position (x,y) and size
(w,h) of the viewer window.
-O <option_string>                         Provide an option string to
reader/writers used to load
-e <extension>                             Load the plugin associated with
handling files with specified
-h or –help                               Display this information
-l <library>                               Load the plugin

You may notice that most of the options come from osgViewer, which is the base class for the viewer. This gives the advantage, that one can use the “normal” osgViewer controls such as flying around the scene. Try holding the right mouse button and moving the mouse up or down for zooming out or in. Or press F for toggling fullscreen mode or press S for toggling the stats (fps, etc.) display.

You may supply multiple .jps files at the command line.  I.e. ./siv *.jps will display all jps files in the current folder 😉

Once the first image of the list is being displayed you may use CURSOR_UP/DOWN or the mouse wheel to select a different image for being displayed. In future versions I may implement a diashow function…

When displaying an image the filename of the image is displayed in the lower left corner.

You can find some jps images for trying out the viewer on:  Stereo Images From Juneau.

Possible Problems:

As default SIF starts in fullscreen quad buffered stereo mode. Thus if your graphics hardware does not support this mode, the viewer will exit with the following error:

Error: Not able to create requested visual.
GraphicsWindow has not been created successfully.
Viewer::realize() – failed to set up any windows

In this case try anaglyphic mode or the apropiate 3D mode for your hardware (see the –stereo option).

You may experience the application segfaulting. Most possibly the reason is that your OpenSceneGraph lacks the library in the lib/osgPlugins folder. If you strace the application and the last thing it tries before segfaulting is to access, this is the reason. The Problem will be corrected in the next version of SIV. For now install Jasper and rebuild OpenSceneGraph.


Do not download these files anymore unless you explicitely want this version. New version is available at: SIV-1.0 released

I decided to publish the viewer under the creative common noncommercial license. Make sure you have the OpenScenegraph library installed before trying to compile or run the viewer. You may download the full source (Eclipse Project) from here: SIV-source (764) or an x86_64 binary from here: SIV-x86_64 (795). More binary formats may be available in the future. Fore the x86_64 binary you’ll need OpenSceneGraph-2.8.

Binaries for most linux distributions can be downloaded from  Instructions on how to build OpenSceneGraph on gentoo can be found on PlopByte.

Building from source:

For building from source unpack the zip and cd to siv/Release and run make.

Future plans:

For the future I’d like to implement a diashow function and to integrate the VR920 headtracking into the viewer. It would be really cool to view a sea panorama image in 3D by turning the head :) This is the reason why the image is not being displayed plain, but on a cylinder segment. For the tracking I’ll have to write a driver for the VR920 headtracking  first, to get the camera viewmatrix for the viewer. Since in Vuzix Forums I found a non working driver,  from which I was able to learn how to read the sensor data, I only have to implement the neccesary calculations and calibration methods.

Well, I hope you enjoy the 3rd dimension. If you like the viewer feel free to link to

Stay tuned for updates


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