>> I know how to extract the image zenith or nadir using Adjust.
>> Easy.  But how do you extract using a script?
>> 
>> Reason I want to do it this way - I have large (6400 x 3200)
>> equirectangular panoramas and want to extract the tops and
>> bottoms for editing, but need to bypass the huge RAM overhead
>> Photoshop requires.  Tried to use GraphicConverter, but this
>> app. doesn't work with images wider than 4000 pixels.
>> 
>> So, any ideas?  Inserting an image into a pano is easy via
>> scripts, now how do you go the other way?!

>PTStitcher can use equirectangular input images and create rectilinear
>images.
>So you could try to create a rectilinear 'panorama' using 1 image from an
>'equirectangular lens'.

Ah (slaps forehead!), of course.  Yes.  Thankyou.

After a bit of fiddling, I got the following to work to extract
the cap out of a equirectangular pano:

p f0 w2000 h2000 v80 nTIFF
m g1.8 i2
i f4 w6400 h3200 y0 p0 r0 v360  n"pano.jpg"  a0 b0 c0 d0 e0 X0 Y0 Z0
o f4 v360  r0 y0 p-90

N.B. the 'o' line pitch directive is back-to-front!  Must use +90
to extract nadir (base) and -90 to extract cap (zenith), which is
the reverse of the values used when inserting images.