BUILD: switch to use pillow instead

create_caption still relies on ImageMagick

graphics/text/tint.py

@@ -0,0 +1,55 @@
+#/usr/bin/env python
+
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2017 Martin Miller
+# https://stackoverflow.com/questions/12251896/colorize-image-while-preserving-transparency-with-pil
+
+from PIL import Image
+from ImageColor import getcolor, getrgb
+from ImageOps import grayscale
+
+def image_tint(image, tint=None):
+	if tint is None:
+		return image
+	if image.mode not in ['RGB', 'RGBA']:
+		image = image.convert('RGBA')
+
+	tr, tg, tb = getrgb(tint)
+	tl = getcolor(tint, "L")  # tint color's overall luminosity
+	if not tl:
+		tl = 1  # avoid division by zero
+	tl = float(tl)  # compute luminosity preserving tint factors
+	sr, sg, sb = map(lambda tv: tv / tl, (tr, tg, tb)
+						)  # per component adjustments
+
+	# create look-up tables to map luminosity to adjusted tint
+	# (using floating-point math only to compute table)
+	luts = (map(lambda lr: int(lr * sr + 0.5), range(256)) +
+			map(lambda lg: int(lg * sg + 0.5), range(256)) +
+			map(lambda lb: int(lb * sb + 0.5), range(256)))
+	l = grayscale(image)  # 8-bit luminosity version of whole image
+	if Image.getmodebands(image.mode) < 4:
+		merge_args = (image.mode, (l, l, l))  # for RGB verion of grayscale
+	else:  # include copy of image's alpha layer
+		a = Image.new("L", image.size)
+		a.putdata(image.getdata(3))
+		merge_args = (image.mode, (l, l, l, a))  # for RGBA verion of grayscale
+		luts += range(256)  # for 1:1 mapping of copied alpha values
+
+	return Image.merge(*merge_args).point(luts)
+
+def main(input_image_path, tintcolor, result_image_path):
+	image = Image.open(input_image_path)
+
+	image.load()
+
+	result = image_tint(image, tintcolor)
+	if os.path.exists(result_image_path):  # delete any previous result file
+		os.remove(result_image_path)
+	result.save(result_image_path)  # file name's extension determines format
+
+if __name__ == '__main__':
+	import os
+	import sys
+
+	main(sys.argv[1], sys.argv[2], sys.argv[3])