#
# The Python Imaging Library.
# $Id$
#
# standard channel operations
#
# History:
# 1996-03-24 fl Created
# 1996-08-13 fl Added logical operations (for "1" images)
# 2000-10-12 fl Added offset method (from Image.py)
#
# Copyright (c) 1997-2000 by Secret Labs AB
# Copyright (c) 1996-2000 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
from . import Image
[文档]def constant(image, value):
"""Fill a channel with a given grey level.
:rtype: :py:class:`~PIL.Image.Image`
"""
return Image.new("L", image.size, value)
[文档]def duplicate(image):
"""Copy a channel. Alias for :py:meth:`PIL.Image.Image.copy`.
:rtype: :py:class:`~PIL.Image.Image`
"""
return image.copy()
[文档]def invert(image):
"""
Invert an image (channel).
.. code-block:: python
out = MAX - image
:rtype: :py:class:`~PIL.Image.Image`
"""
image.load()
return image._new(image.im.chop_invert())
[文档]def lighter(image1, image2):
"""
Compares the two images, pixel by pixel, and returns a new image containing
the lighter values. At least one of the images must have mode "1".
.. code-block:: python
out = max(image1, image2)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_lighter(image2.im))
[文档]def darker(image1, image2):
"""
Compares the two images, pixel by pixel, and returns a new image containing
the darker values. At least one of the images must have mode "1".
.. code-block:: python
out = min(image1, image2)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_darker(image2.im))
[文档]def difference(image1, image2):
"""
Returns the absolute value of the pixel-by-pixel difference between the two
images. At least one of the images must have mode "1".
.. code-block:: python
out = abs(image1 - image2)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_difference(image2.im))
[文档]def multiply(image1, image2):
"""
Superimposes two images on top of each other.
If you multiply an image with a solid black image, the result is black. If
you multiply with a solid white image, the image is unaffected. At least
one of the images must have mode "1".
.. code-block:: python
out = image1 * image2 / MAX
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_multiply(image2.im))
[文档]def screen(image1, image2):
"""
Superimposes two inverted images on top of each other. At least one of the
images must have mode "1".
.. code-block:: python
out = MAX - ((MAX - image1) * (MAX - image2) / MAX)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_screen(image2.im))
[文档]def add(image1, image2, scale=1.0, offset=0):
"""
Adds two images, dividing the result by scale and adding the
offset. If omitted, scale defaults to 1.0, and offset to 0.0.
At least one of the images must have mode "1".
.. code-block:: python
out = ((image1 + image2) / scale + offset)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_add(image2.im, scale, offset))
[文档]def subtract(image1, image2, scale=1.0, offset=0):
"""
Subtracts two images, dividing the result by scale and adding the offset.
If omitted, scale defaults to 1.0, and offset to 0.0. At least one of the
images must have mode "1".
.. code-block:: python
out = ((image1 - image2) / scale + offset)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_subtract(image2.im, scale, offset))
[文档]def add_modulo(image1, image2):
"""Add two images, without clipping the result. At least one of the images
must have mode "1".
.. code-block:: python
out = ((image1 + image2) % MAX)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_add_modulo(image2.im))
[文档]def subtract_modulo(image1, image2):
"""Subtract two images, without clipping the result. At least one of the
images must have mode "1".
.. code-block:: python
out = ((image1 - image2) % MAX)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_subtract_modulo(image2.im))
[文档]def logical_and(image1, image2):
"""Logical AND between two images. At least one of the images must have
mode "1".
.. code-block:: python
out = ((image1 and image2) % MAX)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_and(image2.im))
[文档]def logical_or(image1, image2):
"""Logical OR between two images. At least one of the images must have
mode "1".
.. code-block:: python
out = ((image1 or image2) % MAX)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_or(image2.im))
[文档]def logical_xor(image1, image2):
"""Logical XOR between two images. At least one of the images must have
mode "1".
.. code-block:: python
out = ((bool(image1) != bool(image2)) % MAX)
:rtype: :py:class:`~PIL.Image.Image`
"""
image1.load()
image2.load()
return image1._new(image1.im.chop_xor(image2.im))
[文档]def blend(image1, image2, alpha):
"""Blend images using constant transparency weight. Alias for
:py:meth:`PIL.Image.Image.blend`.
:rtype: :py:class:`~PIL.Image.Image`
"""
return Image.blend(image1, image2, alpha)
[文档]def composite(image1, image2, mask):
"""Create composite using transparency mask. Alias for
:py:meth:`PIL.Image.Image.composite`.
:rtype: :py:class:`~PIL.Image.Image`
"""
return Image.composite(image1, image2, mask)
def offset(image, xoffset, yoffset=None):
"""Returns a copy of the image where data has been offset by the given
distances. Data wraps around the edges. If **yoffset** is omitted, it
is assumed to be equal to **xoffset**.
:param xoffset: The horizontal distance.
:param yoffset: The vertical distance. If omitted, both
distances are set to the same value.
:rtype: :py:class:`~PIL.Image.Image`
"""
if yoffset is None:
yoffset = xoffset
image.load()
return image._new(image.im.offset(xoffset, yoffset))