The 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").
Functions
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).
constant
ImageChops.constant(image, value) => image
Return a layer with the same size as the given image, but filled with the given pixel value.
duplicate
ImageChops.duplicate(image) => image
Return a copy of the given image.
invert
ImageChops.invert(image) => image
Inverts an image.
out = MAX - image
lighter
ImageChops.lighter(image1, image2) => image
Compares the two images, pixel by pixel, and returns a new image containing the lighter values.
out = max(image1, image2)
darker
ImageChops.darker(image1, image2) => image
Compares the two images, pixel by pixel, and returns a new image containing the darker values.
out = min(image1, image2)
difference
ImageChops.difference(image1, image2) => image
Returns the absolute value of the difference between the two images.
out = abs(image1 - image2)
multiply
ImageChops.multiply(image1, image2) => image
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.
out = image1 * image2 / MAX
screen
ImageChops.screen(image1, image2) => image
Superimposes two inverted images on top of each other.
out = MAX - ((MAX - image1) * (MAX - image2) / MAX)
add
ImageChops.add(image1, image2, scale, offset) => image
Adds two images, dividing the result by scale and adding the offset. If omitted, scale defaults to 1.0, and offset to 0.0.
out = (image1 + image2) / scale + offset
subtract
ImageChops.subtract(image1, image2, scale, offset) => image
Subtracts two images, dividing the result by scale and adding the offset. If omitted, scale defaults to 1.0, and offset to 0.0.
out = (image1 - image2) / scale + offset
blend
ImageChops.blend(image1, image2, alpha) => image
Same as the blend function in the Image module.
composite
ImageChops.composite(image1, image2, mask) => image
Same as the composite function in the Image module.
offset
ImageChops.offset(xoffset, yoffset) => image
ImageChops.offset(offset) => image
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.