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))
def homework_3_problem_3():
# load image
img = I.read_gecko_image()
org = deepcopy(img)
fig = plt.gcf()
fig.suptitle("Problem 3: Lloyd's Algorithm")
plt.subplot(221)
plt.title('original')
plt.imshow(org, cm.Greys_r)
# Apply haar transformation
wavelet.forward(h, img)
plt.subplot(222)
plt.title('forward')
plt.imshow(img, cm.Greys_r)
# store sign and apply thresholding
img, sign = quantization.thresh(img, cutoff=0.8)
# logarithmic codebook guess
x = img[np.where(img > 0)]
init = np.array(
[min(x) * 2**i for i in range(int(np.ceil(np.log2(max(x)/min(x)))))])
# Apply k-means to find optimal codebook
codebook, distortion = vq.kmeans(np.sort(img[np.where(img > 0)]), init)
# Encode image
img, dist = vq.vq(img, codebook)
# Decode image
img = np.array([s*codebook[i] for s, i in zip(sign, img)])
img = img.reshape([256, 256])
plt.subplot(223)
plt.title('after quant')
plt.imshow(img, cm.Greys_r)
# Revert haar transformation
wavelet.inverse(h, img)
plt.subplot(224)
plt.title('reverse')
plt.imshow(img, cm.Greys_r)
plt.show()
import utilities.wavelet as wavelet
import utilities.quantization as quantization
import utilities.image as I
import matplotlib.pyplot as plt
import matplotlib.cm as cm
from copy import deepcopy
from math import sqrt
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)
import utilities.wavelet as wavelet
import utilities.quantization as quantization
import utilities.image as I
import matplotlib.pyplot as plt
import matplotlib.cm as cm
from copy import deepcopy
from math import sqrt
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)