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got DCT-based hashing working reasonably well

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git-svn-id: http://comictagger.googlecode.com/svn/trunk@23 6c5673fe-1810-88d6-992b-cd32ca31540c
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beville@gmail.com 2012-11-09 23:25:32 +00:00
parent a04d8055f3
commit c691f62c0d
1 changed files with 13 additions and 24 deletions
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37
imagehasher.py
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@ -98,41 +98,30 @@ class ImageHasher(object):
"""
import numpy
import scipy.fftpack
numpy.set_printoptions(threshold=10000, linewidth=200, precision=2, suppress=True)
# Step 1,2
im = self.image.resize((32, 32), Image.ANTIALIAS).convert("L")
in_data = numpy.array(im.getdata(), dtype=numpy.dtype('float')).reshape(32, 32)
#print len(im.getdata())
#print in_data
in_data = numpy.asarray(im)
# Step 3
dct = scipy.fftpack.dct( in_data )
dct = scipy.fftpack.dct( in_data.astype(float) )
# Step 4
# NO! -- lofreq_dct = dct[:8,:8].flatten()
# NO? -- lofreq_dct = dct[24:32, 24:32].flatten()
#lofreq_dct = dct[:8, 24:32].flatten()
#print dct[24:32, :8]
# NO! -- lofreq_dct = dct[24:32, :8 ].flatten()
#lofreq_dct = dct[1:9, 1:9].flatten()
lofreq_dct = dct[:8, 24:32].flatten()
#omit = 0
#omit = 7
#omit = 56
#omit = 63
# Just skip the top and left rows when slicing, as suggested somewhere else...
lofreq_dct = dct[1:9, 1:9].flatten()
# Step 5
#avg = ( lofreq_dct.sum() - lofreq_dct[omit] ) / ( lofreq_dct.size - 1 )
avg = ( lofreq_dct.sum() ) / ( lofreq_dct.size )
#print lofreq_dct.sum()
#print lofreq_dct[0]
#print avg, lofreq_dct.size
median = numpy.median( lofreq_dct )
thresh = avg
# Step 6
def compare_value_to_avg(i):
return ( 1 if i > avg else 0 )
def compare_value_to_thresh(i):
return ( 1 if i > thresh else 0 )
bitlist = map(compare_value_to_avg, lofreq_dct)
bitlist = map(compare_value_to_thresh, lofreq_dct)
#Step 7
def set_bit( x, (idx, val) ):