Image
Module¶
The Image
module provides a class with the same name which is
used to represent a PIL image. The module also provides a number of factory
functions, including functions to load images from files, and to create new
images.
Examples¶
The following script loads an image, rotates it 45 degrees, and displays it using an external viewer (usually xv on Unix, and the paint program on Windows).
Open, rotate, and display an image (using the default viewer)¶
from PIL import Image
im = Image.open("bride.jpg")
im.rotate(45).show()
The following script creates nice 128x128 thumbnails of all JPEG images in the current directory.
Create thumbnails¶
from PIL import Image
import glob, os
size = 128, 128
for infile in glob.glob("*.jpg"):
file, ext = os.path.splitext(infile)
im = Image.open(infile)
im.thumbnail(size)
im.save(file + ".thumbnail", "JPEG")
Functions¶
-
PIL.Image.
open
(fp, mode='r')[源代码]¶ Opens and identifies the given image file.
This is a lazy operation; this function identifies the file, but the file remains open and the actual image data is not read from the file until you try to process the data (or call the
load()
method). Seenew()
.参数: - fp – A filename (string), pathlib.Path object or a file object.
The file object must implement
read()
,seek()
, andtell()
methods, and be opened in binary mode. - mode – The mode. If given, this argument must be “r”.
返回: An
Image
object.引发: IOError – If the file cannot be found, or the image cannot be opened and identified.
警告
To protect against potential DOS attacks caused by “decompression bombs” (i.e. malicious files which decompress into a huge amount of data and are designed to crash or cause disruption by using up a lot of memory), Pillow will issue a DecompressionBombWarning if the image is over a certain limit. If desired, the warning can be turned into an error with
warnings.simplefilter('error', Image.DecompressionBombWarning)
or suppressed entirely withwarnings.simplefilter('ignore', Image.DecompressionBombWarning)
. See also the logging documentation to have warnings output to the logging facility instead of stderr.- fp – A filename (string), pathlib.Path object or a file object.
The file object must implement
Image processing¶
-
PIL.Image.
alpha_composite
(im1, im2)[源代码]¶ Alpha composite im2 over im1.
参数: - im1 – The first image. Must have mode RGBA.
- im2 – The second image. Must have mode RGBA, and the same size as the first image.
返回: An
Image
object.
-
PIL.Image.
blend
(im1, im2, alpha)[源代码]¶ Creates a new image by interpolating between two input images, using a constant alpha.:
out = image1 * (1.0 - alpha) + image2 * alpha
参数: - im1 – The first image.
- im2 – The second image. Must have the same mode and size as the first image.
- alpha – The interpolation alpha factor. If alpha is 0.0, a copy of the first image is returned. If alpha is 1.0, a copy of the second image is returned. There are no restrictions on the alpha value. If necessary, the result is clipped to fit into the allowed output range.
返回: An
Image
object.
-
PIL.Image.
composite
(image1, image2, mask)[源代码]¶ Create composite image by blending images using a transparency mask.
参数: - image1 – The first image.
- image2 – The second image. Must have the same mode and size as the first image.
- mask – A mask image. This image can have mode “1”, “L”, or “RGBA”, and must have the same size as the other two images.
-
PIL.Image.
eval
(image, *args)[源代码]¶ Applies the function (which should take one argument) to each pixel in the given image. If the image has more than one band, the same function is applied to each band. Note that the function is evaluated once for each possible pixel value, so you cannot use random components or other generators.
参数: - image – The input image.
- function – A function object, taking one integer argument.
返回: An
Image
object.
Constructing images¶
-
PIL.Image.
new
(mode, size, color=0)[源代码]¶ Creates a new image with the given mode and size.
参数: - mode – The mode to use for the new image. See: 模式.
- size – A 2-tuple, containing (width, height) in pixels.
- color – What color to use for the image. Default is black. If given, this should be a single integer or floating point value for single-band modes, and a tuple for multi-band modes (one value per band). When creating RGB images, you can also use color strings as supported by the ImageColor module. If the color is None, the image is not initialised.
返回: An
Image
object.
-
PIL.Image.
fromarray
(obj, mode=None)[源代码]¶ Creates an image memory from an object exporting the array interface (using the buffer protocol).
If obj is not contiguous, then the tobytes method is called and
frombuffer()
is used.参数: - obj – Object with array interface
- mode – Mode to use (will be determined from type if None) See: 模式.
返回: An image object.
1.1.6 新版功能.
-
PIL.Image.
frombytes
(mode, size, data, decoder_name='raw', *args)[源代码]¶ Creates a copy of an image memory from pixel data in a buffer.
In its simplest form, this function takes three arguments (mode, size, and unpacked pixel data).
You can also use any pixel decoder supported by PIL. For more information on available decoders, see the section Writing Your Own File Decoder.
Note that this function decodes pixel data only, not entire images. If you have an entire image in a string, wrap it in a
BytesIO
object, and useopen()
to load it.参数: - mode – The image mode. See: 模式.
- size – The image size.
- data – A byte buffer containing raw data for the given mode.
- decoder_name – What decoder to use.
- args – Additional parameters for the given decoder.
返回: An
Image
object.
-
PIL.Image.
frombuffer
(mode, size, data, decoder_name='raw', *args)[源代码]¶ Creates an image memory referencing pixel data in a byte buffer.
This function is similar to
frombytes()
, but uses data in the byte buffer, where possible. This means that changes to the original buffer object are reflected in this image). Not all modes can share memory; supported modes include “L”, “RGBX”, “RGBA”, and “CMYK”.Note that this function decodes pixel data only, not entire images. If you have an entire image file in a string, wrap it in a BytesIO object, and use
open()
to load it.In the current version, the default parameters used for the “raw” decoder differs from that used for
frombytes()
. This is a bug, and will probably be fixed in a future release. The current release issues a warning if you do this; to disable the warning, you should provide the full set of parameters. See below for details.参数: - mode – The image mode. See: 模式.
- size – The image size.
- data – A bytes or other buffer object containing raw data for the given mode.
- decoder_name – What decoder to use.
- args –
Additional parameters for the given decoder. For the default encoder (“raw”), it’s recommended that you provide the full set of parameters:
frombuffer(mode, size, data, "raw", mode, 0, 1)
返回: An
Image
object.1.1.4 新版功能.
Registering plugins¶
注解
These functions are for use by plugin authors. Application authors can ignore them.
-
PIL.Image.
register_open
(id, factory, accept=None)[源代码]¶ Register an image file plugin. This function should not be used in application code.
参数: - id – An image format identifier.
- factory – An image file factory method.
- accept – An optional function that can be used to quickly reject images having another format.
-
PIL.Image.
register_mime
(id, mimetype)[源代码]¶ Registers an image MIME type. This function should not be used in application code.
参数: - id – An image format identifier.
- mimetype – The image MIME type for this format.
The Image Class¶
-
class
PIL.Image.
Image
[源代码]¶ This class represents an image object. To create
Image
objects, use the appropriate factory functions. There’s hardly ever any reason to call the Image constructor directly.
An instance of the Image
class has the following
methods. Unless otherwise stated, all methods return a new instance of the
Image
class, holding the resulting image.
-
Image.
convert
(mode=None, matrix=None, dither=None, palette=0, colors=256)[源代码]¶ Returns a converted copy of this image. For the “P” mode, this method translates pixels through the palette. If mode is omitted, a mode is chosen so that all information in the image and the palette can be represented without a palette.
The current version supports all possible conversions between “L”, “RGB” and “CMYK.” The matrix argument only supports “L” and “RGB”.
When translating a color image to black and white (mode “L”), the library uses the ITU-R 601-2 luma transform:
L = R * 299/1000 + G * 587/1000 + B * 114/1000
The default method of converting a greyscale (“L”) or “RGB” image into a bilevel (mode “1”) image uses Floyd-Steinberg dither to approximate the original image luminosity levels. If dither is NONE, all non-zero values are set to 255 (white). To use other thresholds, use the
point()
method.参数: - mode – The requested mode. See: 模式.
- matrix – An optional conversion matrix. If given, this should be 4- or 12-tuple containing floating point values.
- dither – Dithering method, used when converting from mode “RGB” to “P” or from “RGB” or “L” to “1”. Available methods are NONE or FLOYDSTEINBERG (default).
- palette – Palette to use when converting from mode “RGB” to “P”. Available palettes are WEB or ADAPTIVE.
- colors – Number of colors to use for the ADAPTIVE palette. Defaults to 256.
返回类型: 返回: An
Image
object.
The following example converts an RGB image (linearly calibrated according to ITU-R 709, using the D65 luminant) to the CIE XYZ color space:
rgb2xyz = (
0.412453, 0.357580, 0.180423, 0,
0.212671, 0.715160, 0.072169, 0,
0.019334, 0.119193, 0.950227, 0 )
out = im.convert("RGB", rgb2xyz)
-
Image.
copy
()[源代码]¶ Copies this image. Use this method if you wish to paste things into an image, but still retain the original.
返回类型: Image
返回: An Image
object.
-
Image.
crop
(box=None)[源代码]¶ Returns a rectangular region from this image. The box is a 4-tuple defining the left, upper, right, and lower pixel coordinate.
This is a lazy operation. Changes to the source image may or may not be reflected in the cropped image. To break the connection, call the
load()
method on the cropped copy.参数: box – The crop rectangle, as a (left, upper, right, lower)-tuple. 返回类型: Image
返回: An Image
object.
-
Image.
draft
(mode, size)[源代码]¶ Configures the image file loader so it returns a version of the image that as closely as possible matches the given mode and size. For example, you can use this method to convert a color JPEG to greyscale while loading it, or to extract a 128x192 version from a PCD file.
Note that this method modifies the
Image
object in place. If the image has already been loaded, this method has no effect.参数: - mode – The requested mode.
- size – The requested size.
-
Image.
filter
(filter)[源代码]¶ Filters this image using the given filter. For a list of available filters, see the
ImageFilter
module.参数: filter – Filter kernel. 返回: An Image
object.
-
Image.
getbands
()[源代码]¶ Returns a tuple containing the name of each band in this image. For example, getbands on an RGB image returns (“R”, “G”, “B”).
返回: A tuple containing band names. 返回类型: tuple
-
Image.
getbbox
()[源代码]¶ Calculates the bounding box of the non-zero regions in the image.
返回: The bounding box is returned as a 4-tuple defining the left, upper, right, and lower pixel coordinate. If the image is completely empty, this method returns None.
-
Image.
getcolors
(maxcolors=256)[源代码]¶ Returns a list of colors used in this image.
参数: maxcolors – Maximum number of colors. If this number is exceeded, this method returns None. The default limit is 256 colors. 返回: An unsorted list of (count, pixel) values.
-
Image.
getdata
(band=None)[源代码]¶ Returns the contents of this image as a sequence object containing pixel values. The sequence object is flattened, so that values for line one follow directly after the values of line zero, and so on.
Note that the sequence object returned by this method is an internal PIL data type, which only supports certain sequence operations. To convert it to an ordinary sequence (e.g. for printing), use list(im.getdata()).
参数: band – What band to return. The default is to return all bands. To return a single band, pass in the index value (e.g. 0 to get the “R” band from an “RGB” image). 返回: A sequence-like object.
-
Image.
getextrema
()[源代码]¶ Gets the the minimum and maximum pixel values for each band in the image.
返回: For a single-band image, a 2-tuple containing the minimum and maximum pixel value. For a multi-band image, a tuple containing one 2-tuple for each band.
-
Image.
getpalette
()[源代码]¶ Returns the image palette as a list.
返回: A list of color values [r, g, b, …], or None if the image has no palette.
-
Image.
getpixel
(xy)[源代码]¶ Returns the pixel value at a given position.
参数: xy – The coordinate, given as (x, y). 返回: The pixel value. If the image is a multi-layer image, this method returns a tuple.
-
Image.
histogram
(mask=None, extrema=None)[源代码]¶ Returns a histogram for the image. The histogram is returned as a list of pixel counts, one for each pixel value in the source image. If the image has more than one band, the histograms for all bands are concatenated (for example, the histogram for an “RGB” image contains 768 values).
A bilevel image (mode “1”) is treated as a greyscale (“L”) image by this method.
If a mask is provided, the method returns a histogram for those parts of the image where the mask image is non-zero. The mask image must have the same size as the image, and be either a bi-level image (mode “1”) or a greyscale image (“L”).
参数: mask – An optional mask. 返回: A list containing pixel counts.
-
Image.
paste
(im, box=None, mask=None)[源代码]¶ Pastes another image into this image. The box argument is either a 2-tuple giving the upper left corner, a 4-tuple defining the left, upper, right, and lower pixel coordinate, or None (same as (0, 0)). If a 4-tuple is given, the size of the pasted image must match the size of the region.
If the modes don’t match, the pasted image is converted to the mode of this image (see the
convert()
method for details).Instead of an image, the source can be a integer or tuple containing pixel values. The method then fills the region with the given color. When creating RGB images, you can also use color strings as supported by the ImageColor module.
If a mask is given, this method updates only the regions indicated by the mask. You can use either “1”, “L” or “RGBA” images (in the latter case, the alpha band is used as mask). Where the mask is 255, the given image is copied as is. Where the mask is 0, the current value is preserved. Intermediate values will mix the two images together, including their alpha channels if they have them.
See
alpha_composite()
if you want to combine images with respect to their alpha channels.参数: - im – Source image or pixel value (integer or tuple).
- box –
An optional 4-tuple giving the region to paste into. If a 2-tuple is used instead, it’s treated as the upper left corner. If omitted or None, the source is pasted into the upper left corner.
If an image is given as the second argument and there is no third, the box defaults to (0, 0), and the second argument is interpreted as a mask image.
- mask – An optional mask image.
-
Image.
point
(lut, mode=None)[源代码]¶ Maps this image through a lookup table or function.
参数: - lut – A lookup table, containing 256 (or 65336 if self.mode==”I” and mode == “L”) values per band in the image. A function can be used instead, it should take a single argument. The function is called once for each possible pixel value, and the resulting table is applied to all bands of the image.
- mode – Output mode (default is same as input). In the current version, this can only be used if the source image has mode “L” or “P”, and the output has mode “1” or the source image mode is “I” and the output mode is “L”.
返回: An
Image
object.
-
Image.
putalpha
(alpha)[源代码]¶ Adds or replaces the alpha layer in this image. If the image does not have an alpha layer, it’s converted to “LA” or “RGBA”. The new layer must be either “L” or “1”.
参数: alpha – The new alpha layer. This can either be an “L” or “1” image having the same size as this image, or an integer or other color value.
-
Image.
putdata
(data, scale=1.0, offset=0.0)[源代码]¶ Copies pixel data to this image. This method copies data from a sequence object into the image, starting at the upper left corner (0, 0), and continuing until either the image or the sequence ends. The scale and offset values are used to adjust the sequence values: pixel = value*scale + offset.
参数: - data – A sequence object.
- scale – An optional scale value. The default is 1.0.
- offset – An optional offset value. The default is 0.0.
-
Image.
putpalette
(data, rawmode='RGB')[源代码]¶ Attaches a palette to this image. The image must be a “P” or “L” image, and the palette sequence must contain 768 integer values, where each group of three values represent the red, green, and blue values for the corresponding pixel index. Instead of an integer sequence, you can use an 8-bit string.
参数: data – A palette sequence (either a list or a string).
-
Image.
putpixel
(xy, value)[源代码]¶ Modifies the pixel at the given position. The color is given as a single numerical value for single-band images, and a tuple for multi-band images.
Note that this method is relatively slow. For more extensive changes, use
paste()
or theImageDraw
module instead.See:
参数: - xy – The pixel coordinate, given as (x, y).
- value – The pixel value.
-
Image.
quantize
(colors=256, method=None, kmeans=0, palette=None)[源代码]¶ Convert the image to ‘P’ mode with the specified number of colors.
参数: - colors – The desired number of colors, <= 256
- method – 0 = median cut 1 = maximum coverage 2 = fast octree
- kmeans – Integer
- palette – Quantize to the
PIL.ImagingPalette
palette.
返回: A new image
-
Image.
resize
(size, resample=0)[源代码]¶ Returns a resized copy of this image.
参数: - size – The requested size in pixels, as a 2-tuple: (width, height).
- resample – An optional resampling filter. This can be
one of
PIL.Image.NEAREST
(use nearest neighbour),PIL.Image.BILINEAR
(linear interpolation),PIL.Image.BICUBIC
(cubic spline interpolation), orPIL.Image.LANCZOS
(a high-quality downsampling filter). If omitted, or if the image has mode “1” or “P”, it is setPIL.Image.NEAREST
.
返回: An
Image
object.
-
Image.
rotate
(angle, resample=0, expand=0)[源代码]¶ Returns a rotated copy of this image. This method returns a copy of this image, rotated the given number of degrees counter clockwise around its centre.
参数: - angle – In degrees counter clockwise.
- resample – An optional resampling filter. This can be
one of
PIL.Image.NEAREST
(use nearest neighbour),PIL.Image.BILINEAR
(linear interpolation in a 2x2 environment), orPIL.Image.BICUBIC
(cubic spline interpolation in a 4x4 environment). If omitted, or if the image has mode “1” or “P”, it is setPIL.Image.NEAREST
. - expand – Optional expansion flag. If true, expands the output image to make it large enough to hold the entire rotated image. If false or omitted, make the output image the same size as the input image.
返回: An
Image
object.
-
Image.
save
(fp, format=None, **params)[源代码]¶ Saves this image under the given filename. If no format is specified, the format to use is determined from the filename extension, if possible.
Keyword options can be used to provide additional instructions to the writer. If a writer doesn’t recognise an option, it is silently ignored. The available options are described in the image format documentation for each writer.
You can use a file object instead of a filename. In this case, you must always specify the format. The file object must implement the
seek
,tell
, andwrite
methods, and be opened in binary mode.参数: - fp – A filename (string), pathlib.Path object or file object.
- format – Optional format override. If omitted, the format to use is determined from the filename extension. If a file object was used instead of a filename, this parameter should always be used.
- options – Extra parameters to the image writer.
返回: None
引发: - KeyError – If the output format could not be determined from the file name. Use the format option to solve this.
- IOError – If the file could not be written. The file may have been created, and may contain partial data.
-
Image.
seek
(frame)[源代码]¶ Seeks to the given frame in this sequence file. If you seek beyond the end of the sequence, the method raises an EOFError exception. When a sequence file is opened, the library automatically seeks to frame 0.
Note that in the current version of the library, most sequence formats only allows you to seek to the next frame.
See
tell()
.参数: frame – Frame number, starting at 0. 引发: EOFError – If the call attempts to seek beyond the end of the sequence.
-
Image.
show
(title=None, command=None)[源代码]¶ Displays this image. This method is mainly intended for debugging purposes.
On Unix platforms, this method saves the image to a temporary PPM file, and calls either the xv utility or the display utility, depending on which one can be found.
On OS X, this method saves the image to a temporary BMP file, and opens it with the native Preview application.
On Windows, it saves the image to a temporary BMP file, and uses the standard BMP display utility to show it (usually Paint).
参数: - title – Optional title to use for the image window, where possible.
- command – command used to show the image
-
Image.
split
()[源代码]¶ Split this image into individual bands. This method returns a tuple of individual image bands from an image. For example, splitting an “RGB” image creates three new images each containing a copy of one of the original bands (red, green, blue).
返回: A tuple containing bands.
-
Image.
thumbnail
(size, resample=3)[源代码]¶ Make this image into a thumbnail. This method modifies the image to contain a thumbnail version of itself, no larger than the given size. This method calculates an appropriate thumbnail size to preserve the aspect of the image, calls the
draft()
method to configure the file reader (where applicable), and finally resizes the image.Note that this function modifies the
Image
object in place. If you need to use the full resolution image as well, apply this method to acopy()
of the original image.参数: - size – Requested size.
- resample – Optional resampling filter. This can be one
of
PIL.Image.NEAREST
,PIL.Image.BILINEAR
,PIL.Image.BICUBIC
, orPIL.Image.LANCZOS
. If omitted, it defaults toPIL.Image.BICUBIC
. (wasPIL.Image.NEAREST
prior to version 2.5.0)
返回: None
-
Image.
tobitmap
(name='image')[源代码]¶ Returns the image converted to an X11 bitmap.
注解
This method only works for mode “1” images.
参数: name – The name prefix to use for the bitmap variables. 返回: A string containing an X11 bitmap. 引发: ValueError – If the mode is not “1”
-
Image.
tobytes
(encoder_name='raw', *args)[源代码]¶ Return image as a bytes object.
警告
This method returns the raw image data from the internal storage. For compressed image data (e.g. PNG, JPEG) use
save()
, with a BytesIO parameter for in-memory data.参数: - encoder_name – What encoder to use. The default is to use the standard “raw” encoder.
- args – Extra arguments to the encoder.
返回类型: A bytes object.
-
Image.
transform
(size, method, data=None, resample=0, fill=1)[源代码]¶ Transforms this image. This method creates a new image with the given size, and the same mode as the original, and copies data to the new image using the given transform.
参数: - size – The output size.
- method – The transformation method. This is one of
PIL.Image.EXTENT
(cut out a rectangular subregion),PIL.Image.AFFINE
(affine transform),PIL.Image.PERSPECTIVE
(perspective transform),PIL.Image.QUAD
(map a quadrilateral to a rectangle), orPIL.Image.MESH
(map a number of source quadrilaterals in one operation). - data – Extra data to the transformation method.
- resample – Optional resampling filter. It can be one of
PIL.Image.NEAREST
(use nearest neighbour),PIL.Image.BILINEAR
(linear interpolation in a 2x2 environment), orPIL.Image.BICUBIC
(cubic spline interpolation in a 4x4 environment). If omitted, or if the image has mode “1” or “P”, it is set toPIL.Image.NEAREST
.
返回: An
Image
object.
-
Image.
transpose
(method)[源代码]¶ Transpose image (flip or rotate in 90 degree steps)
参数: method – One of PIL.Image.FLIP_LEFT_RIGHT
,PIL.Image.FLIP_TOP_BOTTOM
,PIL.Image.ROTATE_90
,PIL.Image.ROTATE_180
,PIL.Image.ROTATE_270
orPIL.Image.TRANSPOSE
.返回: Returns a flipped or rotated copy of this image.
-
Image.
verify
()[源代码]¶ Verifies the contents of a file. For data read from a file, this method attempts to determine if the file is broken, without actually decoding the image data. If this method finds any problems, it raises suitable exceptions. If you need to load the image after using this method, you must reopen the image file.
-
Image.
load
()[源代码]¶ Allocates storage for the image and loads the pixel data. In normal cases, you don’t need to call this method, since the Image class automatically loads an opened image when it is accessed for the first time. This method will close the file associated with the image.
返回: An image access object. 返回类型: PixelAccess Class or PIL.PyAccess
Attributes¶
Instances of the Image
class have the following attributes:
-
PIL.Image.
format
¶ The file format of the source file. For images created by the library itself (via a factory function, or by running a method on an existing image), this attribute is set to
None
.Type: string
orNone
-
PIL.Image.
mode
¶ Image mode. This is a string specifying the pixel format used by the image. Typical values are “1”, “L”, “RGB”, or “CMYK.” See 模式 for a full list.
Type: string
-
PIL.Image.
size
¶ Image size, in pixels. The size is given as a 2-tuple (width, height).
Type: (width, height)
-
PIL.Image.
palette
¶ Colour palette table, if any. If mode is “P”, this should be an instance of the
ImagePalette
class. Otherwise, it should be set toNone
.Type: ImagePalette
orNone
-
PIL.Image.
info
¶ A dictionary holding data associated with the image. This dictionary is used by file handlers to pass on various non-image information read from the file. See documentation for the various file handlers for details.
Most methods ignore the dictionary when returning new images; since the keys are not standardized, it’s not possible for a method to know if the operation affects the dictionary. If you need the information later on, keep a reference to the info dictionary returned from the open method.
Unless noted elsewhere, this dictionary does not affect saving files.
Type: dict