ImageOps Module

The ImageOps module contains a number of ‘ready-made’ image processing operations. This module is somewhat experimental, and most operators only work on L and RGB images.

Only bug fixes have been added since the Pillow fork.

1.1.3 新版功能.

PIL.ImageOps.autocontrast(image, cutoff=0, ignore=None)

Maximize (normalize) image contrast. This function calculates a histogram of the input image, removes cutoff percent of the lightest and darkest pixels from the histogram, and remaps the image so that the darkest pixel becomes black (0), and the lightest becomes white (255).

参数:

• image – The image to process.
• cutoff – How many percent to cut off from the histogram.
• ignore – The background pixel value (use None for no background).

返回:

An image.

PIL.ImageOps.colorize(image, black, white)

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.

参数:

• image – The image to colorize.
• black – The color to use for black input pixels.
• white – The color to use for white input pixels.

返回:

An image.

PIL.ImageOps.crop(image, border=0)

Remove border from image. The same amount of pixels are removed from all four sides. This function works on all image modes.

也可以参考

crop()

参数:

• image – The image to crop.
• border – The number of pixels to remove.

返回:

An image.

PIL.ImageOps.deform(image, deformer, resample=2)

Deform the image.

参数:

• image – The image to deform.
• deformer – A deformer object. Any object that implements a getmesh method can be used.
• resample – What resampling filter to use.

返回:

An image.

PIL.ImageOps.equalize(image, mask=None)

Equalize the image histogram. This function applies a non-linear mapping to the input image, in order to create a uniform distribution of grayscale values in the output image.

参数:

• image – The image to equalize.
• mask – An optional mask. If given, only the pixels selected by the mask are included in the analysis.

返回:

An image.

PIL.ImageOps.expand(image, border=0, fill=0)

Add border to the image

参数:

• image – The image to expand.
• border – Border width, in pixels.
• fill – Pixel fill value (a color value). Default is 0 (black).

返回:

An image.

PIL.ImageOps.fit(image, size, method=0, bleed=0.0, centering=(0.5, 0.5))

Returns a sized and cropped version of the image, cropped to the requested aspect ratio and size.

This function was contributed by Kevin Cazabon.

参数:

• size – The requested output size in pixels, given as a (width, height) tuple.
• method – What resampling method to use. Default is PIL.Image.NEAREST.
• bleed – Remove a border around the outside of the image (from all four edges. The value is a decimal percentage (use 0.01 for one percent). The default value is 0 (no border).
• centering – Control the cropping position. Use (0.5, 0.5) for center cropping (e.g. if cropping the width, take 50% off of the left side, and therefore 50% off the right side). (0.0, 0.0) will crop from the top left corner (i.e. if cropping the width, take all of the crop off of the right side, and if cropping the height, take all of it off the bottom). (1.0, 0.0) will crop from the bottom left corner, etc. (i.e. if cropping the width, take all of the crop off the left side, and if cropping the height take none from the top, and therefore all off the bottom).

返回:

An image.

PIL.ImageOps.flip(image)

Flip the image vertically (top to bottom).

参数:image – The image to flip. 返回:An image.

PIL.ImageOps.grayscale(image)

Convert the image to grayscale.

参数:image – The image to convert. 返回:An image.

PIL.ImageOps.invert(image)

Invert (negate) the image.

参数:image – The image to invert. 返回:An image.

PIL.ImageOps.mirror(image)

Flip image horizontally (left to right).

参数:image – The image to mirror. 返回:An image.

PIL.ImageOps.posterize(image, bits)

Reduce the number of bits for each color channel.

参数:

• image – The image to posterize.
• bits – The number of bits to keep for each channel (1-8).

返回:

An image.

PIL.ImageOps.solarize(image, threshold=128)

Invert all pixel values above a threshold.

参数:

• image – The image to posterize.
• threshold – All pixels above this greyscale level are inverted.

返回:

An image.