GIMP plugin script to hue-shift an image several times (e.g. for animations)

batch_hue_shift.py

#!/usr/bin/env python

from gimpfu import *
from gimpenums import *
import os

def batch_hue_shift(image, drawable, count, outdir):
  assert 2 <= count <= 360

  folder, filename = os.path.split(image.filename)
  filebase, fileext = os.path.splitext(filename)

  if not outdir:
    outdir = folder

  count = int(count)
  step = 360.0 / count

  # gimp_file_save overwrites the progress bar with the file name every time
  # so setting progress values is essentially pointless

  for i in range(0, count):
    # create a temporary copy of the input image
    # the output image will only have one merged layer!
    dupimage = pdb.gimp_image_duplicate(image)
    dupimage.disable_undo()
    dupimage.merge_visible_layers(CLIP_TO_IMAGE) # flatten() removes alpha
    dupdrawable = dupimage.active_layer

    shift = i*step
    if shift > 180:
      shift -= 360
    pdb.gimp_hue_saturation(dupdrawable, ALL_HUES, shift, 0, 0)

    newname = filebase + ("_%03d" % (i+1)) + fileext
    newpath = os.path.join(outdir, newname)
    pdb.gimp_file_save(dupimage, dupdrawable, newpath, newpath)
    gimp.delete(dupimage)

register(
  "batch_hue_shift",
  "Hue-shifts an image several times",
  "Hue-shifts an image several times",
  "pezcode",
  "(c) 2014 pezcode",
  "2014-09-21",
  "<Image>/_Xtns/Color/Batch _Hue Shift",
  "RGB*",
  [
  (PF_SPINNER, "count",  "Number of images", 20, (2, 360, 1)),
  (PF_DIRNAME, "outdir", "Output directory", "")
  ],
  [],
  batch_hue_shift
)

main()