The Invisible Image was an installation displaying spacer GIFs found on the web.
The original idea for this project was muttered by Christopher Clay and the first incarnation of the installation was on display for the first Paraflows Festival in September 2006 at the metalab in Vienna.
The second incarnation was (much refined) shown at the Museumsquartier in Vienna in 2007. This is basically the version you can find here.
Spacer GIFs, also called blind GIFs though they may as well be of other graphics formats, are an anachronism from the early days of the world wide web: back in the early to mid 1990s, before the advent of cascading style sheets (CSS), means for specifying the layout of a web site - especially ensuring the exact positioning of page elements - were quite limited. And one of them were spacer GIFs. Their purpose was to help position other elements of the page by keeping portions of that page empty, e.g. separating entries of a navigation menu or text columns in a multi-column layout.
Technically, though, these apparently empty spaces are not empty at all. They are occupied by images which just happen to be invisible, a whole species unnoticed by unsuspecting visitors of the sites they dwell on.
Another remarkable propertiy of spacer GIFs is that they constitute a Hack in the classical sense of the word: they are a very clever (ab?)use (generating empty space in a page) of a means (embedding images in a text document) invented for an entirely different purpose (providing illustrations and figures).
They also are a species endangered by extinction: todays means of specifying page layout are vastly superior, thus, rendering spacer GIFs obsolete. This installation is dedicated to these normally unseen images, dragging them out of their niches and hideaways before they die out completely. So this may be your Last Chance (not) To See.
At the core of the installation is a python program that searches the web for spacers using Google Images (by screen scraping - there was no image API back then). More precisely, it searches for images with names that likely will return many spacer GIFs. It then downloads the images and tests them for transparency. If it finds them to be entirely invisible, it will display them.
While it searches for more invisible images, the program shows its progress. Once a spacer GIF has been found you are shown the images meta-data, i.e. its URL, dimensions in pixels, size in Bytes etc. It then switches to display the image itself. In parallel, the layout structure of a page, which references the image, in is also shown in a browser. Page elements are only shown as gray blocks. The deeper nested the element, the brighter it is shown. The spacer GIF itself is appearing in red. This magic is acieved by a Greasemonkey script contributed by Christopher Clay.
In it's current shape, the installation is geared to be run on a Mac.
Most likely this will
In any case, you'll need this:
- Python
- wxWidgets with python bindings (for the display / UI)
- Beautifulsoup (for screen scraping)
- Appscript (for making a Firefox process display the page, seems defunct as of Mac OS 10.8)
- In case you want to run it like the original: a beamer.
Assuming you are using macports, do the following:
sudo port install python27 wxWidgets30 py27-wxpython30 py27-beautifulsoup py27-appscript- Install the Greasemonkey Firefox addon and add add
invisible-image-greasemonkey.jsto you user scripts, activated for all URLs. - run
python2.7 ii.py -dfor testing and debugging andpython2.7 ii.pyfot the full two-screen setup.