PythonDoc Example: The Image Module

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blend(im1, im2, alpha) [#]

Creates a new image by interpolating between the given images, using a constant alpha.

   out = image1 * (1.0 - alpha) + image2 * alpha
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.
Returns:
An Image object.

composite(image1, image2, mask) [#]

Creates a new image by interpolating between the given images, using the mask as alpha.

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 can have mode “1”, “L”, or “RGBA”, and most have the same size as the other two images.

eval(image, function) [#]

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.

image
The input image.
function
A function object, taking one integer argument.
Returns:
An Image object.

frombuffer(mode, size, data, decoder_name=”raw”, *args) [#]

Creates an image memory from pixel data in a string or byte buffer.

This function is similar to fromstring, but it data in the byte buffer, where possible. Images created by this function are usually marked as readonly.

Note that this function decodes pixel data only, not entire images. If you have an entire image in a string, wrap it in a StringIO object, and use open to load it.

mode
The image mode.
size
The image size.
data
An 8-bit string or other buffer object containing raw data for the given mode.
decoder_name
What decoder to use.
*args
Additional parameters for the given decoder.
Returns:
An Image object.

fromstring(mode, size, data, decoder_name=”raw”, *args) [#]

Creates an image memory from pixel data in a string.

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 StringIO object, and use open to load it.

mode
The image mode.
size
The image size.
data
An 8-bit string containing raw data for the given mode.
decoder_name
What decoder to use.
*args
Additional parameters for the given decoder.
Returns:
An Image object.

getmodebase(mode) [#]

Get “base” mode. Given a mode, this function returns “L” for images that contain grayscale data, and “RGB” for images that contain color data.

mode
Input mode.
Returns:
“L” or “RGB”.

getmodetype(mode) [#]

Get storage type mode. Given a mode, this function returns a single-layer mode suitable for storing individual bands.

mode
Input mode.
Returns:
“L”, “I”, or “F”.

Image() (class) [#]

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.

For more information about this class, see The Image Class.

init() [#]

Explicitly load all available file format drivers.

merge(mode, bands) [#]

Creates a new image from a number of single-band images.

mode
The mode to use for the output image.
bands
A sequence containing one single-band image for each band in the output image. All bands must have the same size.
Returns:
An Image object.

new(mode, size, color=0) [#]

Creates a new image with the given mode and size.

mode
The mode to use for the new image.
size
A 2-tuple, containing (width, height)
color
What colour 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 colour strings as supported by the ImageColor module. If the colour is None, the image is not initialised.
Returns:
An Image object.

open(file, mode=”r”) [#]

Opens and identifies the given image file.

This is a lazy operation; this function identifies the file, but the actual image data is not read from the file until you try to process the data (or call the load method).

file
A filename (string) or a file object. The file object must implement read, seek, and tell methods, and be opened in binary mode.
mode
The mode. If given, this argument must be “r”.
Returns:
An Image object.

preinit() [#]

Explicitly load standard file format drivers.

register_extension(id, extension) [#]

Register an image extension. This function should not be used in application code.

id
An image format identifier.
extension
An extension used for this format.

register_mime(id, mimetype) [#]

Register an image MIME type. This function should not be used in application code.

id
An image format identifier.
mimetype
The image MIME type for this format.

register_open(id, factory, accept=None) [#]

Register an image file plugin. This function should not be used in application code.

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.

register_save(id, driver) [#]

Register an image save function. This function should not be used in application code.

id
An image format identifier.
driver
A function to save images in this format.

The Image Class #

This class represents an image object.

convert(mode, matrix=None) [#]

Returns a converted copy of an image. For the “P” mode, this 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.”

When translating a colour 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

When translating a greyscale image into a bilevel image (mode “1”), all non-zero values are set to 255 (white). To use other thresholds, use the point method.

mode
The requested mode.
matrix
An optional conversion matrix. If given, this should be 4- or 16-tuple containing floating point values.
Returns:
An Image object.

copy() [#]

Copies the image. Use this method if you wish to paste things into an image, but still retain the original.

Returns:
An Image object.

crop(box=None) [#]

Returns a rectangular region from the current 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.

Returns:
An Image object.

draft(mode, size) [#]

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 colour 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.

mode
The requested mode.
size
The requested size.

filter(filter) [#]

Filter image by the given filter. For a list of available filters, see the ImageFilter module.

filter
Filter kernel.
Returns:
An Image object.

fromstring(data, decoder_name=”raw”, *args) [#]

Same as the fromstring function, but loads data into the current image.

getbands() [#]

Returns a tuple containing the name of each band. For example, getbands on an RGB image returns (“R”, “G”, “B”).

Returns:
A tuple containing band names.

getbbox() [#]

Calculates the bounding box of the non-zero regions in the image.

Returns:
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.

getdata(band=None) [#]

Returns the contents of an 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()).

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).
Returns:
A sequence-like object.

getextrema() [#]

Get the the minimum and maximum pixel values for each band in the image.

Returns:
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.

getpixel(xy) [#]

Returns the pixel value at a given position.

xy
The coordinate, given as (x, y).
Returns:
The pixel value. If the image is a multi-layer image, this method returns a tuple.

histogram(mask=None) [#]

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”).

mask
An optional mask.
Returns:
A list containing pixel counts.

load() [#]

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.

offset(xoffset, yoffset=None) [#]

(Deprecated) Returns a copy of the image where the 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.

This method is deprecated. New code should use the offset function in the ImageChops module.

xoffset
The horizontal distance.
yoffset
The vertical distance. If omitted, both distances are set to the same value.
Returns:
An Image object.

paste(im, box=None, mask=None) [#]

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 colour. When creating RGB images, you can also use colour 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 can be used for transparency effects.

Note that if you paste an “RGBA” image, the alpha band is ignored. You can work around this by using the same image as both source image and mask.

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.
Returns:
An Image object.

point(lut, mode=None) [#]

Map image through lookup table or function.

lut
A lookup table, containing 256 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”.
Returns:
An Image object.

putalpha(alpha) [#]

Replace the alpha layer of the current 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”.

im
The new alpha layer. This can either be an “L” or “1” image having the same size as the current image, or an integer or other color value.

putdata(data, scale=1.0, offset=0.0) [#]

Copy 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.

data
A sequence object.
scale
An optional scale value. The default is 1.0.
offset
An optional offset value. The default is 0.0.

putpalette(data) [#]

Attach a palette to a “P” or “L” image. The palette sequence should 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.

data
A palette sequence.

putpixel(xy, value) [#]

Modifies the pixel at the given position. The colour 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 the ImageDraw module instead.

xy
The pixel coordinate, given as (x, y).
value
The pixel value.

resize(size, filter=NEAREST) [#]

Returns a resized copy of an image.

size
The requested size in pixels, as a 2-tuple: (width, height).
filter
An optional resampling filter. This can be one of NEAREST (use nearest neighbour), BILINEAR (linear interpolation in a 2x2 environment), BICUBIC (cubic spline interpolation in a 4x4 environment), or ANTIALIAS (a high-quality downsampling filter). If omitted, or if the image has mode “1” or “P”, it is set NEAREST.
Returns:
An Image object.

rotate(angle, filter=NEAREST) [#]

Returns a rotated image. This method returns a copy of an image, rotated the given number of degrees counter clockwise around its centre.

angle
In degrees counter clockwise.
filter
An optional resampling filter. This can be one of NEAREST (use nearest neighbour), BILINEAR (linear interpolation in a 2x2 environment), or BICUBIC (cubic spline interpolation in a 4x4 environment). If omitted, or if the image has mode “1” or “P”, it is set NEAREST.
Returns:
An Image object.

save(file, format=None, **options) [#]

Saves the 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 later in this handbook.

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, and write methods, and be opened in binary mode.

file
File name 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.
Returns:
None

seek(frame) [#]

Seeks to the given frame in a 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.

frame
Frame number, starting at 0.

show(title=None) [#]

Displays an image. This method is mainly intended for debugging purposes.

On Unix platforms, this method saves the image to a temporary PPM file, and calls the xv utility.

On Windows, it saves the image to a temporary BMP file, and uses the standard BMP display utility to show it (usually Paint).

title
Optional title to use for the image window, where possible.

split() [#]

Split image into individual bands. This methods 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).

Returns:
A tuple containing bands.

tell() [#]

Returns the current frame number.

Returns:
Frame number, starting with 0.

thumbnail(size, resample=NEAREST) [#]

Make 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 the bilinear and bicubic filters in the current version of PIL are not well-suited for thumbnail generation. You should use ANTIALIAS unless speed is much more important than quality.

Also 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 a copy of the original image.

size
Requested size.
resample
Optional resampling filter. This can be one of NEAREST, BILINEAR, BICUBIC, or ANTIALIAS (best quality). If omitted, it defaults to NEAREST (this will be changed to ANTIALIAS in future versions).
Returns:
None

tobitmap(name=”image”) [#]

Returns the image converted to an X11 bitmap. This method only works for mode “1” images.

name
The name prefix to use for the bitmap variables.
Returns:
A string containing an X11 bitmap.

tostring(encoder_name=”raw”, *args) [#]

Returns a string containing pixel data.

encoder_name
What encoder to use. The default is to use the standard “raw” encoder.
*args
Extra arguments to the encoder.
Returns:
An 8-bit string.

transform(size, method, data, resample=NEAREST) [#]

Transform 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.

size
The output size.
method
The transformation method. This is one of EXTENT (cut out a rectangular subregion), AFFINE (affine transform), QUAD (map a quadrilateral to a rectangle), or 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 NEAREST (use nearest neighbour), BILINEAR (linear interpolation in a 2x2 environment), or BICUBIC (cubic spline interpolation in a 4x4 environment). If omitted, or if the image has mode “1” or “P”, it is set to NEAREST.
Returns:
An Image object.

transpose(method) [#]

Returns a flipped or rotated copy of an image.

method
One of FLIP_LEFT_RIGHT, FLIP_TOP_BOTTOM, ROTATE_90, ROTATE_180, or ROTATE_270.

verify() [#]

Verify file contents. 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.

 

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