USAGE: pano2fisheye [-p projection] [-v viewtype] [-d dimension] [-b bgcolor] [-f fade] [-s smooth] [-n newseed] infile outfile
USAGE: pano2fisheye [-h or -help]

-p ... projection ... fisheye projection type: choices are linear, stereographic, or
..................... orthographic; default=linear
-v ... viewtype ..... type of view; choices are: planet or manhole; planet is a view
..................... looking down from the sky; manhole is a view from the ground up;
..................... default=planet
-d ... dimension .... square dimension of output; integer>0; default is the height
..................... of the input
-b ... bgcolor ...... bgcolor is the color for the area outside the
..................... circle of the fisheye area; any valid IM color is permitted or
..................... the special name of "stars" to create a black background with
..................... random point star field; use none to make the background
..................... transparent; default=white
-f ... fade ......... amount of fade in pixels between the image and background color
..................... at the top of the image for viewtype=planet; integer>=0;
..................... default=0
-s ... smooth ....... amount of smoothing for antialiasing when bgcolor=none;
..................... float>=0; default=0
-n ... newseed ...... random seed for creating the star field when bgcolor=stars

PURPOSE: To transforms a spherical panorama to a fisheye view.

DESCRIPTION: FISHEYE is designed to transform a spherical (equirectangular) panorama to a fisheye view. There are 3 choices for the fisheye format: linear, stereographics and orthographic. The spherical (equirectangular) panorama's pixels represent x=longitude and y=latitude. That is, both x and y are angular units. Longitude corresponds to 360 degree range. Thus the left and right sides must wrap contiguously. Thus a width to height aspect of 2:1. An image can be faked by cropping to w/h aspect of 2:1 (width is twice the height), then mirroring it horizontally, appending horizontally, then cropping the center half and rolling it horizontally 50%.

ARGUMENTS:

-p projection ... PROJECTION is the fisheye projection type. Choices are linear (l), stereographic (s), or orthographic (o). The default=linear.

-v viewtype ... VIEWTYPE is the type of view. Choices are: planet (p) or manhole (m). The choice of planet is a view looking down from the sky. The choice of manhole is a view from the ground up. The default=planet.

-d dimension ... DIMENSION is the square dimension of output image. Values are integers>0. The default is the height of the input.

-b bgcolor ... BGCOLOR is the color for the area outside the circle of the fisheye region. Any valid IM color is permitted or the special name of "stars" to create a black background with random point star field. Use "none" to make the background transparent. The default=white.

-f fade ... FADE is the amount of fade in pixels between the top of the input image and background color for viewtype=planet. This is a preprocessing step so that the outside of the fisheye circular region will fade to the background color. Values are integers>=0. The default=0.

-s smooth ... SMOOTH is the amount of smoothing for antialiasing when bgcolor=none or stars. Values are float>=0. The default=0.

-n newseed .. .NEWSEED is the random seed for creating the star field when bgcolor=stars. Values are integers>=0. The default is totally random star placement from run-to-run.

REFERENCES:
http://en.wikipedia.org/wiki/Fisheye_lens
http://www.bobatkins.com/photography/technical/field_of_view.html
http://www.photographymad.com/pages/view/little-planet-photos-5-simple-steps-to-making-panorama-worlds

NOTE: This script will be slow due to the use of -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.