image

matplotlib.image

The image module supports basic image loading, rescaling and display operations.

class matplotlib.image.AxesImage(ax, cmap=None, norm=None, interpolation=None, origin=None, extent=None, filternorm=1, filterrad=4.0, resample=False, **kwargs)

Bases: matplotlib.image._ImageBase

interpolation and cmap default to their rc settings

cmap is a colors.Colormap instance norm is a colors.Normalize instance to map luminance to 0-1

extent is data axes (left, right, bottom, top) for making image plots registered with data plots. Default is to label the pixel centers with the zero-based row and column indices.

Additional kwargs are matplotlib.artist properties

get_cursor_data(event)

Get the cursor data for a given event

get_extent()

Get the image extent: left, right, bottom, top

get_window_extent(renderer=None)

make_image(renderer, magnification=1.0, unsampled=False)

set_extent(extent)

extent is data axes (left, right, bottom, top) for making image plots

This updates ax.dataLim, and, if autoscaling, sets viewLim to tightly fit the image, regardless of dataLim. Autoscaling state is not changed, so following this with ax.autoscale_view will redo the autoscaling in accord with dataLim.

class matplotlib.image.BboxImage(bbox, cmap=None, norm=None, interpolation=None, origin=None, filternorm=1, filterrad=4.0, resample=False, interp_at_native=True, **kwargs)

Bases: matplotlib.image._ImageBase

The Image class whose size is determined by the given bbox.

cmap is a colors.Colormap instance norm is a colors.Normalize instance to map luminance to 0-1

interp_at_native is a flag that determines whether or not interpolation should still be applied when the image is displayed at its native resolution. A common use case for this is when displaying an image for annotational purposes; it is treated similarly to Photoshop (interpolation is only used when displaying the image at non-native resolutions).

kwargs are an optional list of Artist keyword args

contains(mouseevent)

Test whether the mouse event occured within the image.

get_transform()

get_window_extent(renderer=None)

make_image(renderer, magnification=1.0, unsampled=False)

class matplotlib.image.FigureImage(fig, cmap=None, norm=None, offsetx=0, offsety=0, origin=None, **kwargs)

Bases: matplotlib.image._ImageBase

cmap is a colors.Colormap instance norm is a colors.Normalize instance to map luminance to 0-1

kwargs are an optional list of Artist keyword args

get_extent()

Get the image extent: left, right, bottom, top

make_image(renderer, magnification=1.0, unsampled=False)

set_data(A)

Set the image array.

zorder = 0

class matplotlib.image.NonUniformImage(ax, **kwargs)

Bases: matplotlib.image.AxesImage

kwargs are identical to those for AxesImage, except that ‘nearest’ and ‘bilinear’ are the only supported ‘interpolation’ options.

get_extent()

make_image(renderer, magnification=1.0, unsampled=False)

set_array(*args)

set_cmap(cmap)

set_data(x, y, A)

Set the grid for the pixel centers, and the pixel values.

x and y are monotonic 1-D ndarrays of lengths N and M,

respectively, specifying pixel centers

A is an (M,N) ndarray or masked array of values to be

colormapped, or a (M,N,3) RGB array, or a (M,N,4) RGBA array.

set_filternorm(s)

set_filterrad(s)

set_interpolation(s)

set_norm(norm)

class matplotlib.image.PcolorImage(ax, x=None, y=None, A=None, cmap=None, norm=None, **kwargs)

Bases: matplotlib.image.AxesImage

Make a pcolor-style plot with an irregular rectangular grid.

This uses a variation of the original irregular image code, and it is used by pcolorfast for the corresponding grid type.

cmap defaults to its rc setting

cmap is a colors.Colormap instance norm is a colors.Normalize instance to map luminance to 0-1

Additional kwargs are matplotlib.artist properties

get_cursor_data(event)

Get the cursor data for a given event

make_image(renderer, magnification=1.0, unsampled=False)

set_array(*args)

set_data(x, y, A)

Set the grid for the rectangle boundaries, and the data values.

x and y are monotonic 1-D ndarrays of lengths N+1 and M+1,

respectively, specifying rectangle boundaries. If None, they will be created as uniform arrays from 0 through N and 0 through M, respectively.

A is an (M,N) ndarray or masked array of values to be

colormapped, or a (M,N,3) RGB array, or a (M,N,4) RGBA array.

matplotlib.image.composite_images(images, renderer, magnification=1.0)

Composite a number of RGBA images into one. The images are composited in the order in which they appear in the images list.

Parameters:

images : list of Images

Each must have a make_image method. For each image, can_composite should return True, though this is not enforced by this function. Each image must have a purely affine transformation with no shear.

renderer : RendererBase instance

magnification : float

The additional magnification to apply for the renderer in use.

Returns:

tuple : image, offset_x, offset_y

Returns the tuple:

• image: A numpy array of the same type as the input images.
• offset_x, offset_y: The offset of the image (left, bottom) in the output figure.

matplotlib.image.imread(fname, format=None)

Read an image from a file into an array.

fname may be a string path, a valid URL, or a Python file-like object. If using a file object, it must be opened in binary mode.

If format is provided, will try to read file of that type, otherwise the format is deduced from the filename. If nothing can be deduced, PNG is tried.

Return value is a numpy.array. For grayscale images, the return array is MxN. For RGB images, the return value is MxNx3. For RGBA images the return value is MxNx4.

matplotlib can only read PNGs natively, but if PIL is installed, it will use it to load the image and return an array (if possible) which can be used with imshow(). Note, URL strings may not be compatible with PIL. Check the PIL documentation for more information.

matplotlib.image.imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None, origin=None, dpi=100)

Save an array as in image file.

The output formats available depend on the backend being used.

Arguments:

fname:

A string containing a path to a filename, or a Python file-like object. If format is None and fname is a string, the output format is deduced from the extension of the filename.

arr:

An MxN (luminance), MxNx3 (RGB) or MxNx4 (RGBA) array.

Keyword arguments:

vmin/vmax: [ None | scalar ]

vmin and vmax set the color scaling for the image by fixing the values that map to the colormap color limits. If either vmin or vmax is None, that limit is determined from the arr min/max value.

cmap:

cmap is a colors.Colormap instance, e.g., cm.jet. If None, default to the rc image.cmap value.

format:

One of the file extensions supported by the active backend. Most backends support png, pdf, ps, eps and svg.

origin

[ ‘upper’ | ‘lower’ ] Indicates where the [0,0] index of the array is in the upper left or lower left corner of the axes. Defaults to the rc image.origin value.

dpi

The DPI to store in the metadata of the file. This does not affect the resolution of the output image.

matplotlib.image.pil_to_array(pilImage)

Load a PIL image and return it as a numpy array. For grayscale images, the return array is MxN. For RGB images, the return value is MxNx3. For RGBA images the return value is MxNx4

matplotlib.image.thumbnail(infile, thumbfile, scale=0.1, interpolation='bilinear', preview=False)

make a thumbnail of image in infile with output filename thumbfile.

infile the image file – must be PNG or Pillow-readable if you

have Pillow installed

thumbfile

the thumbnail filename

scale

the scale factor for the thumbnail

interpolation

the interpolation scheme used in the resampling

preview

if True, the default backend (presumably a user interface backend) will be used which will cause a figure to be raised if show() is called. If it is False, a pure image backend will be used depending on the extension, ‘png’->FigureCanvasAgg, ‘pdf’->FigureCanvasPdf, ‘svg’->FigureCanvasSVG

See examples/misc/image_thumbnail.py.

misc example code: image_thumbnail.py

Return value is the figure instance containing the thumbnail