import numpy as np
def to_matplotlib(img):
"""Returns a view of the image from Bob format to matplotlib format.
This function works with images, batches of images, videos, and higher
dimensional arrays that contain images.
Parameters
----------
img : numpy.ndarray
A N dimensional array containing an image in Bob format (channels
first): For an ND array (N >= 3), the image should have the following
format: ``(..., c, h, w)``.
Returns
-------
numpy.ndarray
A view of the ``img`` compatible with
:py:func:`matplotlib.pyplot.imshow`.
"""
if img.ndim < 3:
return img
return np.moveaxis(img, -3, -1)
[docs]def to_bob(img):
"""Returns a view of the image from matplotlib format to Bob format.
This function works with images, batches of images, videos, and higher
dimensional arrays that contain images.
Parameters
----------
img : numpy.ndarray
An image in matplotlib format (channels last): For an ND array (N >= 3),
the image should have the following format: ``(..., h, w, c)``.
Returns
-------
numpy.ndarray
A view of the ``img`` compatible with Bob.
"""
if img.ndim < 3:
return img
return np.moveaxis(img, -1, -3)
[docs]def opencvbgr_to_bob(img):
"""Returns a view of the image from OpenCV BGR format to Bob RGB format.
This function works with images, batches of images, videos, and higher
dimensional arrays that contain images.
Parameters
----------
img : numpy.ndarray
An image loaded by OpenCV. It needs to have at least 3 dimensions.
Returns
-------
numpy.ndarray
A view of the ``img`` compatible with Bob.
Raises
------
ValueError
If the image dimension is less than 3.
"""
if img.ndim < 3:
raise ValueError("You need to provide at least a 3 dimensional image")
img = img[..., ::-1]
return to_bob(img)
[docs]def bob_to_opencvbgr(img):
"""Returns a view of the image from Bob format to OpenCV BGR format.
This function works with images, batches of images, videos, and higher
dimensional arrays that contain images.
Parameters
----------
img : numpy.ndarray
An image loaded by Bob. It needs to have at least 3 dimensions.
Returns
-------
numpy.ndarray
A view of the ``img`` compatible with OpenCV.
Raises
------
ValueError
If the image dimension is less than 3.
"""
if img.ndim < 3:
raise ValueError("You need to provide at least a 3 dimensional image")
img = img[..., ::-1, :, :]
return to_matplotlib(img)
def imshow(img, cmap=None, **kwargs):
"""Plots the images that are returned by :py:func:`bob.io.base.load`
Parameters
----------
img : numpy.ndarray
A 2 or 3 dimensional array containing an image in
bob style: For a 2D array (grayscale image) should be ``(h, w)``;
A 3D array (color image) should be in the ``(c, h, w)`` format.
cmap : matplotlib.colors.Colormap
Colormap, optional, default: ``None``.
If ``cmap`` is ``None`` and ``img.ndim`` is 2, defaults to 'gray'.
``cmap`` is ignored when ``img`` has RGB(A) information.
**kwargs
These are passed directly to :py:func:`matplotlib.pyplot.imshow`
Returns
-------
object
Returns whatever ``plt.imshow`` returns.
"""
import matplotlib.pyplot as plt
if cmap is None and img.ndim == 2:
cmap = "gray"
return plt.imshow(to_matplotlib(img), cmap=cmap, **kwargs)