Well, this version seems to work cleanly under GIMP 2.4.1 (Windows). I got a new definition of set-pt from a different source, but it looks exactly the same. I moved the (define outside the main (let* and removed the declaration of (a). I'll test to see if it runs under Ubuntu (2.4.0) when I get home.

Dave

------ ; Urban Acid
; David Hathaway
;
; A script to fake the "Urban Acid" look within The Gimp version 2. ;
; This script is based on:
;
http://www.scrapjazz.com/community/jazzclub/showthread.php?t=89073&page=3&pp=15 ;
; This program is free software; you can redistribute it and/or modify ; it under the terms of the GNU General Public License as published by ; the Free Software Foundation; either version 2 of the License, or ; (at your option) any later version. ;
; This program is distributed in the hope that it will be useful, ; but WITHOUT ANY WARRANTY; without even the implied warranty of ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ; GNU General Public License for more details. ;
; You should have received a copy of the GNU General Public License ; along with this program; if not, write to the Free Software ; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. ;
; Version 0.5 - first working version ; Version 0.6 - modified to work on GIMP 2.4 ; Version 0.6.5 - modified to work on GIMP 2.4.1

(define (urban-acid img drawable)

; compatibility hack ; http://www.lefinnois.net/scriptfu_gimp24/chrominium.scm (define (set-pt a index x y)
(begin
(aset a (* index 2) x)
(aset a (+ (* index 2) 1) y) )
)

; set some system variables (let*
(
(copy-layer)
(splineValue)
(splineRed)
(splineGreen)
(splineBlue)
)

;7) create a duplicate layer of the base layer. (set! copy-layer (car (gimp-layer-copy drawable 0))) (gimp-layer-set-name copy-layer "Copy") (gimp-image-add-layer img copy-layer 0)

(define (splineValue) (let* ((a (cons-array 10 'byte))) (set-pt a 0 0 0)
(set-pt a 1 44 27)
(set-pt a 2 99 117)
(set-pt a 3 195 229)
(set-pt a 4 255 255)
a
)
)
(gimp-curves-spline copy-layer VALUE-LUT 10 (splineValue))

(define (splineRed) (let* ((a (cons-array 10 'byte))) (set-pt a 0 0 0)
(set-pt a 1 51 6)
(set-pt a 2 151 137)
(set-pt a 3 204 228)
(set-pt a 4 255 255)
a
)
)
(gimp-curves-spline copy-layer RED-LUT 10 (splineRed))

(define (splineGreen) (let* ((a (cons-array 10 'byte))) (set-pt a 0 0 0)
(set-pt a 1 38 31)
(set-pt a 2 125 129)
(set-pt a 3 197 223)
(set-pt a 4 255 255)
a
)
)
(gimp-curves-spline copy-layer GREEN-LUT 10 (splineGreen))

(define (splineBLue) (let* ((a (cons-array 8 'byte))) (set-pt a 0 0 0)
(set-pt a 1 22 33)
(set-pt a 2 149 126)
(set-pt a 4 255 255)
a
)
)
(gimp-curves-spline copy-layer BLUE-LUT 8 (splineRed))

(gimp-layer-set-mode copy-layer HARDLIGHT-MODE) (gimp-layer-set-opacity copy-layer 80)

) ; let*

; Flush the display (gimp-displays-flush)
)

(script-fu-register "urban-acid" "U_rban Acid"
"This script sets the curves based on the Urban Acid formula"
"David Hathaway " "(c) David Hathaway" "2007 11 08"
"RGB*"
SF-IMAGE "Image" 0 SF-DRAWABLE "Layer to start on (unused)" 0 )
(script-fu-menu-register "urban-acid" "/Filters/Dave77459")