Fred's ImageMagick Scripts


    Copyright © Fred Weinhaus

    My scripts are available free of charge for non-commercial (non-profit) use, ONLY.

    For use of my scripts in commercial (for-profit) environments or non-free applications, please contact me (Fred Weinhaus) for licensing arrangements. My email address is fmw at alink dot net.

    If you: 1) redistribute, 2) incorporate any of these scripts into other free applications or 3) reprogram them in another scripting language, then you must contact me for permission, especially if the result might be used in a commercial or for-profit environment.

    Usage, whether stated or not in the script, is restricted to the above licensing arrangements. It is also subject, in a subordinate manner, to the ImageMagick license, which can be found at:

    Please read the Pointers For Use on my home page to properly install and customize my scripts.


Applies a kaleidoscope effect to an image.

Download Script

last modified: December 15, 2018

USAGE: kaleidoscope [-s sides] [-c xc,yc] [-i irot] [-o orot] [-v vp] infile outfile
USAGE: kaleidoscope [-h or -help]

-s .... sides ......... sides; integer; sides>1; default=3
-c .... xc,yc ......... x,y center coordinates for the effect;
....................... integers>=0; default=image center
-i .... irot .......... input rotation; integer; 0<=irot<=360; default=0
-o .... orot .......... output rotation; integer; 0<=orot<=360; default=0
-v .... vp ............ virtual-pixel method;
....................... any non-background method

PURPOSE: To apply a kaleidoscope effect to an image.

DESCRIPTION: KALEIDOSCOPE applies a kaleidoscope effect to an image.


-s sides ... SIDES is the number of kaleidoscope sides. Values are integers greater than 1. The default=3

-c xc,yc ... XC,YC are the center coordinates for the kaleidoscope effect in the image. Values are integers. The default is the image center.

-i irot ... IROT is the input rotation of the image. Values are integers between 0 and 360 degrees. The default is 0.

-o orot ... OROT is the output rotation of the image. Values are integers between 0 and 360 degrees. The default is 0.

NOTE: The script is very slow due to the use of a complicated formula evaluated using -fx.

CAVEAT: No guarantee that this script will work on all platforms, nor that trapping of inconsistent parameters is complete and foolproof. Use At Your Own Risk.




-s 3

-s 5

-s 7

What the script does is as follows:

  • Applies a complicated formulate to an image using -fx

This is equivalent to the following IM commands

  • pi2=`convert xc: -format "%[fx:2*pi]" info:`
  • dx="dx=i-$xc;"
  • dy="dy=j-$yc;"
  • rad="rad=hypot(dx,dy);"
  • tt="tt=mod((atan2(dy,dx)+$pi2)*$sides/($pi2),1.0);"
  • ang="ang=2*(tt<0.5?tt:1-tt);"
  • convert $infile -virtual-pixel $vp -monitor \
    -fx "$dx $dy $rad $tt $ang u.p{$xc+rad*cos(ang),$yc+rad*sin(ang)}" \