# The PIL.ImageChops Module

The ImageChops module contains a number of arithmetical image operations, called channel operations ("chops"). These can be used for various purposes, including special effects, image compositions, algorithmic painting, and more.

At this time, channel operations are only implemented for 8-bit images (e.g. "L" and "RGB").

Most channel operations take one or two image arguments and returns a new image. Unless otherwise noted, the result of a channel operation is always clipped to the range 0 to MAX (which is 255 for all modes supported by the operations in this module).

## Module Contents

add(image1, image2, scale=1.0, offset=0) [#]

  Add images ((image1 + image2) / scale + offset).

  Adds two images, dividing the result by scale and adding the offset. If omitted, scale defaults to 1.0, and offset to 0.0.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
add_modulo(image1, image2) [#]

  Add images without clipping ((image1 + image2) % MAX).

  Adds two images, without clipping the result.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
blend(image1, image2, alpha) [#]

  Blend images using constant transparency weight.

  Same as the blend function in the Image module.

composite(image1, image2, mask) [#]

  Create composite using transparency mask.

  Same as the composite function in the Image module.

constant(image, value) [#]

  Return an image with the same size as the given image, but filled with the given pixel value.

  image
    Reference image.
  value
    Pixel value.
  Returns:
    An image object.
darker(image1, image2) [#]

  Compare images, and return darker pixel value (min(image1, image2)).

  Compares the two images, pixel by pixel, and returns a new image containing the darker values.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
difference(image1, image2) [#]

  Calculate absolute difference (abs(image1 - image2)).

  Returns the absolute value of the difference between the two images.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
duplicate(image) [#]

  Copy image.

  image
    Source image.
  Returns:
    A copy of the source image.
invert(image) [#]

  Inverts an image (MAX - image).

  image
    Source image.
  Returns:
    An image object.
lighter(image1, image2) [#]

  Compare images, and return lighter pixel value (max(image1, image2)).

  Compares the two images, pixel by pixel, and returns a new image containing the lighter values.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
logical_and(image1, image2) [#]

  Logical AND (image1 and image2).

logical_or(image1, image2) [#]

  Logical OR (image1 or image2).

logical_xor(image1, image2) [#]

  Logical XOR (image1 xor image2).

multiply(image1, image2) [#]

  Superimpose positive images (image1 * image2 / MAX).

  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.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
offset(image, xoffset, yoffset=None) [#]

  Offset image data.

  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.

  image
    Source image.
  xoffset
    The horizontal distance.
  yoffset
    The vertical distance. If omitted, both distances are set to the same value.
  Returns:
    An Image object.
screen(image1, image2) [#]

  Superimpose negative images (MAX - ((MAX - image1) * (MAX - image2) / MAX)).

  Superimposes two inverted images on top of each other.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
subtract(image1, image2, scale=1.0, offset=0) [#]

  Subtract images ((image1 - image2) / scale + offset).

  Subtracts two images, dividing the result by scale and adding the offset. If omitted, scale defaults to 1.0, and offset to 0.0.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.
subtract_modulo(image1, image2) [#]

  Subtract images without clipping ((image1 - image2) % MAX).

  Subtracts two images, without clipping the result.

  image1
    First image.
  image1
    Second image.
  Returns:
    An image object.