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.


Creates a tunnel-like effect on an image.

Download Script

last modified: December 16, 2018

USAGE: tunnelize [-m mode] infile outfile
USAGE: tunnelize [-h or -help]

-m .... mode ..... mode of transform; mode=1 or 2; default=1

PURPOSE: To create a tunnel-like effect on an image.

DESCRIPTION: TUNNELIZE creates a tunnel-like effect on an image by swapping polar for cartesian coordinates.


-m mode ... MODE is either 1 or 2. Mode=1 swaps angle for x and radius for y. Mode=2 swaps radius for x and angle for y.

NOTE: This script may run rather slowly as it uses -fx. A similar effect to mode=1 can be achieved using -distort arc "360 90 size 0", where size is in the range of half one or the other dimensions of the image or as large as the half diagonal of the image.

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.


Image Tunnelization


-m 1

-m 2

Comparison To -Distort Arc

-distort arc "360 90 121 0"
(height/2 = 121)

-distort arc "360 90 160 0"
(width/2 = 160)

Image Tunnelization


-m 1

-m 2

What the script does is as follows:

  • Calculates the polar coordinates from the cartesian coordinates
  • Scales the cartesian coordinates by the ratio of the polar coordinates
    divided by the maximum polar coordinates

This is equivalent to the following IM commands for the case of -m 1.

  • w2=`convert $infile -format "%[fx:w/2]" info:`
  • h2=`convert $infile -format "%[fx:h/2]" info:`
  • r2=`convert $infile -format "%[fx:hypot(w/2,h/2)]" info:`
  • pi2=`convert xc: -format "%[fx:2*pi]" info:`
  • convert $infile -monitor \
    -fx "xx=(i-$w2); yy=(j-$h2); rr=hypot(xx,yy); aa=atan2(yy,xx); u.p{(aa+pi)*w/$pi2,rr*h/$r2}" \