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adding three-color feature to ImageOps.colorize

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This commit is contained in:
tsennott 2018-07-06 18:18:06 -07:00
parent 937443f2a6
commit 63d8637bb8
1 changed files with 31 additions and 9 deletions
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40
src/PIL/ImageOps.py
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@ -136,28 +136,50 @@ def autocontrast(image, cutoff=0, ignore=None):
return _lut(image, lut)
def colorize(image, black, white):
def colorize(image, black, white, mid=None, midpoint=128):
"""
Colorize grayscale image. The **black** and **white**
arguments should be RGB tuples; this function calculates a color
wedge mapping all black pixels in the source image to the first
color, and all white pixels to the second color.
Colorize grayscale image.
This function calculates a color wedge mapping all
black pixels in the source image to the first
color, and all white pixels to the second color. If
mid is specified, it uses three color mapping.
The **black** and **white**
arguments should be RGB tuples; optionally you can use
three color mapping by also specifying **mid**, and
optionally, **midpoint** (which is the integer value
in [0, 255] corresponding to the midpoint color,
default 128).
:param image: The image to colorize.
:param black: The color to use for black input pixels.
:param white: The color to use for white input pixels.
:param mid: The color to use for midtone input pixels.
:param midpoint: the int value [0, 255] for the mid color.
:return: An image.
"""
assert image.mode == "L"
black = _color(black, "RGB")
if mid is not None:
mid = _color(mid, "RGB")
white = _color(white, "RGB")
red = []
green = []
blue = []
for i in range(256):
red.append(black[0]+i*(white[0]-black[0])//255)
green.append(black[1]+i*(white[1]-black[1])//255)
blue.append(black[2]+i*(white[2]-black[2])//255)
if mid is None:
for i in range(256):
red.append(black[0] + i * (white[0] - black[0]) // 255)
green.append(black[1] + i * (white[1] - black[1]) // 255)
blue.append(black[2] + i * (white[2] - black[2]) // 255)
else:
for i in range(0, midpoint):
red.append(black[0] + i * (mid[0] - black[0]) // 255)
green.append(black[1] + i * (mid[1] - black[1]) // 255)
blue.append(black[2] + i * (mid[2] - black[2]) // 255)
for i in range(0, 256 - midpoint):
red.append(mid[0] + i * (white[0] - mid[0]) // 255)
green.append(mid[1] + i * (white[1] - mid[1]) // 255)
blue.append(mid[2] + i * (white[2] - mid[2]) // 255)
image = image.convert("RGB")
return _lut(image, red + green + blue)