发布于 2015-09-11 16:19:35 | 147 次阅读 | 评论: 0 | 来源: 网络整理
#
# 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 PIL import Image
[docs]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)
[docs]def duplicate(image):
"""Copy a channel. Alias for :py:meth:`PIL.Image.Image.copy`.
:rtype: :py:class:`~PIL.Image.Image`
"""
return image.copy()
[docs]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())
[docs]def lighter(image1, image2):
"""
Compares the two images, pixel by pixel, and returns a new image containing
the lighter values.
.. 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))
[docs]def darker(image1, image2):
"""
Compares the two images, pixel by pixel, and returns a new image
containing the darker values.
.. 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))
[docs]def difference(image1, image2):
"""
Returns the absolute value of the pixel-by-pixel difference between the two
images.
.. 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))
[docs]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.
.. 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))
[docs]def screen(image1, image2):
"""
Superimposes two inverted images on top of each other.
.. 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))
[docs]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.
.. 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))
[docs]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.
.. 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))
[docs]def add_modulo(image1, image2):
"""Add two images, without clipping the result.
.. 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))
[docs]def subtract_modulo(image1, image2):
"""Subtract two images, without clipping the result.
.. 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))
[docs]def logical_and(image1, image2):
"""Logical AND between two images.
.. 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))
[docs]def logical_or(image1, image2):
"""Logical OR between two images.
.. 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))
def logical_xor(image1, image2):
"""Logical XOR between two images.
.. 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))
[docs]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)
[docs]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)
[docs]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))