visprint(1)

NAME

visprint- Fractal fingerprint generator.

SYNTAX

md5sum (sha1sum) foo.bar | visprint [Options] > foo.png

DESCRIPTION

Visprint makes cool fractal fingerprint png images based on the contents of any file. The image will be different for almost every file with even slightly different contents. Visprint uses the IFS fractal generation process, pioneered by Michael Barnsley. It is a way to create images which are self-similar to infinite depths. In other words, the picture is made up of smaller versions of itself. Visprint takes a checksum as its input. This is usually a 32-byte number which is generated from a file. In order to generate the checksum, you will also need a hash function command such as md5sum or sha1sum.

OPTIONS

-b(0-255)
    Use the given background brightness. 0 means black, 255 means white. You can try other values, but the resultant image will be quite ugly. The default is 0 (black).

-c  Use the alternate coloring method. Flips RGB to BGR.

-a  Create the fractal with 4 different color areas.

-g  Create a semi-grayscale image. The output varies heavily depending on the -b switch.

-i(1-lots)
    Use the given intensity of color. With a black background, a higher intensity produces a brighter image. With a white background, higher intensity produces a darker image. In all cases, calculation time doubles every time you double the intensity. The default is 30.

-l(32-128)
    Use the given checksum length. Modify this number to match the hash function you are using. Examples: 32 for md5, 40 for sha1, 64 for sha256, 128 for sha512... The output of 128 is foggy (but still useful). Higher values will result in crappy images, therefore 128 is the maximum accepted. The default value is 32.

-r(1-1000)
    Use the given value for both the x and y resolutions. The calculation time will quadruple every time you double this value. The default is 300.

-t  Create the image with a transparent background.

-v  Output version information and exit.

-?, -h, --help
    Output help information and exit.

EXAMPLES

To create a nice 500x500 fingerprint of your kernel type:

md5sum /boot/mykernel | visprint -r500 > mykernel.png

Let's say that you want a 100x100 sha1 fingerprint of your website's index file, with png transparency that looks good on a white background:

sha1sum index.html | visprint -l -r100 -b255 -t > index.png

AUTHORS

Current Maintainer:
    Goizeder Ruiz de Gopegui http://www.tastyrabbit.net/visprint

Previous Geniuses:
    Ian Golderg: http://http.cs.berkeley.edu/~iang/ Raph Leviev: http://www.cs.berkeley.edu/~raph/ Hal Finney: http://www.rain.org/~hal/ David Johnston: http://www.cybercities.com/ston/ Soren Andersen: http://intrepid.perlmonk.org/ The original code was written by Ian Goldberg, based on an idea by Hal Finney, in a post to the coderpunks mailing list. The most excellent color enhancements were added by Raph Levien. David Johnston made a port for Win95 console mode and added a bunch of nice features. Soren Andersen developed the png and transparency code. Goizeder Ruiz de Gopegui, the current maintainer, cleaned the code, created the documentation and put everything together.

COPYRIGHT

Copyright 2007 Goizeder Ruiz de Gopegui

This is free software.  You may redistribute copies of it under the terms of the GNU General Public License.

http://www.gnu.org/licenses/gpl.html.

There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

md5sum(1) sha1sum(1)