# 需要导入模块: import cv2 [as 别名]
# 或者: from cv2 import CV_LOAD_IMAGE_COLOR [as 别名]
def _load_cv2(img, grayscale=None):
"""
TODO
"""
# load images if given filename, or convert as needed to opencv
# Alpha layer just causes failures at this point, so flatten to RGB.
# RGBA: load with -1 * cv2.CV_LOAD_IMAGE_COLOR to preserve alpha
# to matchTemplate, need template and image to be the same wrt having alpha
if grayscale is None:
grayscale = GRAYSCALE_DEFAULT
if isinstance(img, (str, unicode)):
# The function imread loads an image from the specified file and
# returns it. If the image cannot be read (because of missing
# file, improper permissions, unsupported or invalid format),
# the function returns an empty matrix
# http://docs.opencv.org/3.0-beta/modules/imgcodecs/doc/reading_and_writing_images.html
if grayscale:
img_cv = cv2.imread(img, LOAD_GRAYSCALE)
else:
img_cv = cv2.imread(img, LOAD_COLOR)
if img_cv is None:
raise IOError("Failed to read %s because file is missing, "
"has improper permissions, or is an "
"unsupported or invalid format" % img)
elif isinstance(img, numpy.ndarray):
# don't try to convert an already-gray image to gray
if grayscale and len(img.shape) == 3: # and img.shape[2] == 3:
img_cv = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
else:
img_cv = img
elif hasattr(img, 'convert'):
# assume its a PIL.Image, convert to cv format
img_array = numpy.array(img.convert('RGB'))
img_cv = img_array[:, :, ::-1].copy() # -1 does RGB -> BGR
if grayscale:
img_cv = cv2.cvtColor(img_cv, cv2.COLOR_BGR2GRAY)
else:
raise TypeError('expected an image filename, OpenCV numpy array, or PIL image')
return img_cv
