# coding: utf-8
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"""This module provides conversions between numpy.ndarray and QImage
- :func:`convertArrayToQImage`
- :func:`convertQImageToArray`
"""
from __future__ import division
__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "04/09/2018"
import sys
import numpy
from numpy.lib.stride_tricks import as_strided as _as_strided
from .. import qt
[docs]def convertArrayToQImage(array):
"""Convert an array-like image to a QImage.
The created QImage is using a copy of the array data.
Limitation: Only RGB or RGBA images with 8 bits per channel are supported.
:param array: Array-like image data of shape (height, width, channels)
Channels are expected to be either RGB or RGBA.
:type array: numpy.ndarray of uint8
:return: Corresponding Qt image with RGB888 or ARGB32 format.
:rtype: QImage
"""
array = numpy.array(array, copy=False, order='C', dtype=numpy.uint8)
if array.ndim != 3 or array.shape[2] not in (3, 4):
raise ValueError(
'Image must be a 3D array with 3 or 4 channels per pixel')
if array.shape[2] == 4:
format_ = qt.QImage.Format_ARGB32
# RGBA -> ARGB + take care of endianness
if sys.byteorder == 'little': # RGBA -> BGRA
array = array[:, :, (2, 1, 0, 3)]
else: # big endian: RGBA -> ARGB
array = array[:, :, (3, 0, 1, 2)]
array = numpy.array(array, order='C') # Make a contiguous array
else: # array.shape[2] == 3
format_ = qt.QImage.Format_RGB888
height, width, depth = array.shape
qimage = qt.QImage(
array.data,
width,
height,
array.strides[0], # bytesPerLine
format_)
return qimage.copy() # Making a copy of the image and its data
[docs]def convertQImageToArray(image):
"""Convert a QImage to a numpy array.
If QImage format is not Format_RGB888, Format_RGBA8888 or Format_ARGB32,
it is first converted to one of this format depending on
the presence of an alpha channel.
The created numpy array is using a copy of the QImage data.
:param QImage image: The QImage to convert.
:return: The image array of RGB or RGBA channels of shape
(height, width, channels (3 or 4))
:rtype: numpy.ndarray of uint8
"""
rgba8888 = getattr(qt.QImage, 'Format_RGBA8888', None) # Only in Qt5
# Convert to supported format if needed
if image.format() not in (qt.QImage.Format_ARGB32,
qt.QImage.Format_RGB888,
rgba8888):
if image.hasAlphaChannel():
image = image.convertToFormat(
rgba8888 if rgba8888 is not None else qt.QImage.Format_ARGB32)
else:
image = image.convertToFormat(qt.QImage.Format_RGB888)
format_ = image.format()
channels = 3 if format_ == qt.QImage.Format_RGB888 else 4
ptr = image.bits()
if qt.BINDING == 'PyQt5':
ptr.setsize(image.byteCount())
elif qt.BINDING in ('PySide2', 'PySide6'):
ptr = ptr.tobytes()
else:
raise RuntimeError("Unsupported Qt binding: %s" % qt.BINDING)
# Create an array view on QImage internal data
view = _as_strided(
numpy.frombuffer(ptr, dtype=numpy.uint8),
shape=(image.height(), image.width(), channels),
strides=(image.bytesPerLine(), channels, 1))
if format_ == qt.QImage.Format_ARGB32:
# Convert from ARGB to RGBA
# Not a byte-ordered format: do care about endianness
if sys.byteorder == 'little': # BGRA -> RGBA
view = view[:, :, (2, 1, 0, 3)]
else: # big endian: ARGB -> RGBA
view = view[:, :, (1, 2, 3, 0)]
# Format_RGB888 and Format_RGBA8888 do not need reshuffling channels:
# They are byte-ordered and already in the right order
return numpy.array(view, copy=True, order='C')
