def get_percent_difference(file1, file2):
"""
Performs pixel comparison of two files, given by their paths |file1|
and |file2| using terminal tool 'perceptualdiff' and returns percentage
difference of the total file size.
@param file1: path to image
@param file2: path to secondary image
@return: percentage difference of total file size.
@raise ValueError: if image dimensions are not the same
@raise OSError: if file does not exist or cannot be opened.
"""
# Using pdiff image comparer to compare the two images. This class
# invokes the terminal tool perceptualdiff.
pdi = pdiff_image_comparer.PdiffImageComparer()
diff_bytes = pdi.compare(file1, file2)[0]
return round(100. * diff_bytes / os.path.getsize(file1))
def make_pdiff_comparer(self):
"""
@returns a PDiffImageComparer object.
"""
return pdiff_image_comparer.PdiffImageComparer()