def problem_5():
img = im.read_gecko_image()
plt.figure()
plt.subplot(1, 3, 1)
plt.title('Original Image')
plt.imshow(img, cm.Greys_r)
# Forward Transform
img_fwd = copy.deepcopy(img)
dim = max(img.shape)
while dim >= 8:
P = wv.permutation_matrix(dim)
T_a = wv.cdf_24_encoding_transform(dim)
img_fwd[:dim, :dim] = P.dot(T_a).dot(
img_fwd[:dim, :dim]).dot(T_a.T).dot(P.T)
dim = dim / 2
plt.subplot(1, 3, 2)
plt.title('Transformed Image')
plt.imshow(img_fwd, cm.Greys_r)
# Threshold + Encode
t, ltmax = quant.log_thresh(img_fwd, cutoff=0.98)
img_encode = quant.encode(img_fwd, t, ltmax)
# Store to file
filename = 'encoded_image'
img_encode.tofile(filename)
file_size = os.stat(filename).st_size
# Compress File
subprocess.call(['gzip', filename])
c_file_size = os.stat(filename + '.gz').st_size
# Decompress File
subprocess.call(['gunzip', filename + '.gz'])
# # Read from file
img_encode = np.fromfile(filename).reshape(img.shape)
# Decode Image
img_decode = quant.decode(img_encode, t, ltmax)
# Inverse Transform
img_inv = copy.deepcopy(img_decode)
dim = 8
while dim <= max(img.shape):
P = wv.permutation_matrix(dim)
T_b = wv.cdf_24_decoding_transform(dim)
img_inv[:dim, :dim] = T_b.T.dot(P.T).dot(
img_inv[:dim, :dim]).dot(P).dot(T_b)
dim = dim * 2
plt.subplot(1, 3, 3)
plt.title('Recreated Image')
plt.imshow(img_inv, cm.Greys_r)
plt.show()
print "Compression Level: %s" % (1 - float(c_file_size) / float(file_size))
img = I.read_gecko_image()
org = deepcopy(img)
fig = plt.gcf()
fig.suptitle('Logarithmic quantizationuantization')
plt.subplot(231)
plt.title('original')
plt.imshow(org, cm.Greys_r)
haar_coefficients = [1/sqrt(2), 1/sqrt(2)]
wavelet.forward(h=haar_coefficients, image=img)
plt.subplot(232)
plt.title('forward')
plt.imshow(img, cm.Greys_r)
offset = 4
for idx, th in enumerate([0.8, 0.9, 0.95]):
img_cp = deepcopy(img)
thresh, lmaxt = quantization.log_thresh(img_cp, th)
img_cp = quantization.encode(img_cp, thresh, lmaxt)
img_cp = quantization.decode(img_cp, thresh, lmaxt)
wavelet.inverse(h=haar_coefficients, image=img_cp)
plt.subplot(eval('23%s' % (offset + idx)))
plt.title('%s' % th)
plt.imshow(img_cp, cm.Greys_r)
plt.show()
img = I.read_gecko_image()
org = deepcopy(img)
fig = plt.gcf()
fig.suptitle('Logarithmic quantizationuantization')
plt.subplot(231)
plt.title('original')
plt.imshow(org, cm.Greys_r)
haar_coefficients = [1 / sqrt(2), 1 / sqrt(2)]
wavelet.forward(h=haar_coefficients, image=img)
plt.subplot(232)
plt.title('forward')
plt.imshow(img, cm.Greys_r)
offset = 4
for idx, th in enumerate([0.8, 0.9, 0.95]):
img_cp = deepcopy(img)
thresh, lmaxt = quantization.log_thresh(img_cp, th)
img_cp = quantization.encode(img_cp, thresh, lmaxt)
img_cp = quantization.decode(img_cp, thresh, lmaxt)
wavelet.inverse(h=haar_coefficients, image=img_cp)
plt.subplot(eval('23%s' % (offset + idx)))
plt.title('%s' % th)
plt.imshow(img_cp, cm.Greys_r)
plt.show()