Chromatic Aberration Plugin for GIMP

A chromatic aberration plugin for GNU Image Manipulation Program. Tested on version 2.10.

See GIMP Plugin Documentation for installation procedure.

;
; 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 3 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, see <https://www.gnu.org/licenses/>.


(define (script-fu-chromatic-aberration inImage inLayer inNumber)

  (let* (
        (theImage inImage)
        (theLayer inLayer)
        (theHeight (car (gimp-drawable-height theLayer)))
        (theWidth (car (gimp-drawable-width theLayer)))
        (aberrationGroup 0)
        (redLayer 0)
        (greenLayer 0)
        (blueLayer 0)
        (aberrationLayer 0)
  )
    
  (gimp-context-push)
  (gimp-context-set-defaults)
  (gimp-image-undo-group-start theImage)
  
  (set! aberrationGroup (car (gimp-layer-group-new theImage)))
  (gimp-item-set-name aberrationGroup "Aberration")
  (gimp-image-insert-layer theImage aberrationGroup 0 0)
  
  (set! blueLayer (car (gimp-layer-copy theLayer TRUE)))
  (gimp-item-set-name blueLayer "Blue")
  (gimp-image-insert-layer theImage blueLayer aberrationGroup 0)
  (gimp-item-set-visible blueLayer TRUE)
  (plug-in-colors-channel-mixer RUN-INTERACTIVE theImage blueLayer FALSE 0 0 0 0 0 0 0 0 1)
  (gimp-layer-set-mode blueLayer LAYER-MODE-NORMAL)
  
  (set! greenLayer (car (gimp-layer-copy theLayer TRUE)))
  (gimp-item-set-name greenLayer "Green")
  (gimp-image-insert-layer theImage greenLayer aberrationGroup 0)
  (gimp-item-set-visible greenLayer TRUE)
  (plug-in-colors-channel-mixer RUN-INTERACTIVE theImage greenLayer FALSE 0 0 0 0 1 0 0 0 0)
  (gimp-layer-set-mode greenLayer LAYER-MODE-ADDITION)
  
  (set! redLayer (car (gimp-layer-copy theLayer TRUE)))
  (gimp-item-set-name redLayer "Red")
  (gimp-image-insert-layer theImage redLayer aberrationGroup 0)
  (gimp-item-set-visible redLayer TRUE)
  (plug-in-colors-channel-mixer RUN-INTERACTIVE theImage redLayer FALSE 1 0 0 0 0 0 0 0 0)
  (gimp-layer-set-mode redLayer LAYER-MODE-ADDITION)
  
  ;Wipes layers into one another to smooth the spectrum. 
  ;Motion blur is performed before lens distortion to hide frame edges. 
  (plug-in-mblur-inward RUN-NONINTERACTIVE theImage redLayer   2 (/ inNumber 13) 0 (/ theWidth 2) (/ theHeight 2))
  (plug-in-mblur-inward RUN-NONINTERACTIVE theImage greenLayer 2 (/ inNumber 26) 0 (/ theWidth 2) (/ theHeight 2))
  (plug-in-mblur        RUN-NONINTERACTIVE theImage greenLayer 2 (/ inNumber 26) 0 (/ theWidth 2) (/ theHeight 2))
  (plug-in-mblur        RUN-NONINTERACTIVE theImage blueLayer  2 (/ inNumber 13) 0 (/ theWidth 2) (/ theHeight 2))
  
  ;Red layer is distorted twice as much as green; both are "zoomed in" while blue stays the same.
  (plug-in-lens-distortion RUN-INTERACTIVE theImage redLayer   0 0 (/ (* -1 inNumber) 5.0) 0 0 0)
  (plug-in-lens-distortion RUN-INTERACTIVE theImage greenLayer 0 0 (/ (* -1 inNumber) 10.0) 0 0 0)
  
  (set! aberrationLayer (car (gimp-image-merge-layer-group theImage aberrationGroup)))
  
  (gimp-image-undo-group-end theImage)
  (gimp-displays-flush)
  (gimp-context-pop)
  )
)

(script-fu-register "script-fu-chromatic-aberration"
  _"_Chromatic Aberration..."
  _"Apply a simple chromatic aberration effect."
  "Matthew Schellenberg"
  "2024, Matthew Schellenberg"
  "January 29, 2024"
  "RGB*"
  SF-IMAGE       "Image"      0
  SF-DRAWABLE    "Drawable"   0
  SF-ADJUSTMENT _"Aberration" '(40 0 150 1 1 0 0)
)

(script-fu-menu-register "script-fu-chromatic-aberration" "<Image>/Filters/Blur")