def lcn_2d(im, sigmas=[1.591, 1.591]):
""" Apply local contrast normalization to a square image.
Uses a scheme described in Pinto et al (2008)
Based on matlab code by Koray Kavukcuoglu
http://cs.nyu.edu/~koray/publis/code/randomc101.tar.gz
data is 2-d
sigmas is a 2-d vector of standard devs (to define local smoothing kernel)
Example
=======
im_p = lcn_2d(im,[1.591, 1.591])
"""
# assert(issubclass(im.dtype.type, np.floating))
im = np.cast[np.float](im)
# 1. subtract the mean and divide by std dev
mn = np.mean(im)
sd = np.std(im, ddof=1)
im -= mn
im /= sd
# # 2. compute local mean and std
# kerstring = '''0.0001 0.0005 0.0012 0.0022 0.0027 0.0022 0.0012 0.0005 0.0001
# 0.0005 0.0018 0.0049 0.0088 0.0107 0.0088 0.0049 0.0018 0.0005
# 0.0012 0.0049 0.0131 0.0236 0.0288 0.0236 0.0131 0.0049 0.0012
# 0.0022 0.0088 0.0236 0.0427 0.0520 0.0427 0.0236 0.0088 0.0022
# 0.0027 0.0107 0.0288 0.0520 0.0634 0.0520 0.0288 0.0107 0.0027
# 0.0022 0.0088 0.0236 0.0427 0.0520 0.0427 0.0236 0.0088 0.0022
# 0.0012 0.0049 0.0131 0.0236 0.0288 0.0236 0.0131 0.0049 0.0012
# 0.0005 0.0018 0.0049 0.0088 0.0107 0.0088 0.0049 0.0018 0.0005
# 0.0001 0.0005 0.0012 0.0022 0.0027 0.0022 0.0012 0.0005 0.0001'''
# ker = []
# for l in kerstring.split('\n'):
# ker.append(np.fromstring(l, dtype=np.float, sep=' '))
# ker = np.asarray(ker)
# lmn = scipy.signal.correlate2d(im, ker, mode='same', boundary='symm')
# lmnsq = scipy.signal.correlate2d(im ** 2, ker, mode='same', boundary='symm')
lmn = gaussian_filter(im, sigmas, mode='reflect')
lmnsq = gaussian_filter(im**2, sigmas, mode='reflect')
lvar = lmnsq - lmn**2
# lvar = np.where( lvar < 0, lvar, 0)
np.clip(lvar, 0, np.inf, lvar) # items < 0 set to 0
lstd = np.sqrt(lvar)
np.clip(lstd, 1, np.inf, lstd)
im -= lmn
im /= lstd
return im
def LCNinput(data, kernel_shape):
X = T.ftensor4()
filter_shape = (1, 1, kernel_shape, kernel_shape)
filters = sharedX(gaussian_filter(kernel_shape).reshape(filter_shape))
convout = conv2d(X, filters=filters, border_mode='full')
# For each pixel, remove mean of 9x9 neighborhood
mid = int(np.floor(kernel_shape/ 2.))
centered_X = X - convout[:,:,mid:-mid,mid:-mid]
# Scale down norm of 9x9 patch if norm is bigger than 1
sum_sqr_XX = conv2d(T.sqr(X), filters=filters, border_mode='full')
denom = T.sqrt(sum_sqr_XX[:,:,mid:-mid,mid:-mid])
per_img_mean = denom.mean(axis = [2,3])
divisor = T.largest(per_img_mean.dimshuffle(0,1, 'x', 'x'), denom)
new_X = centered_X / T.maximum(1., divisor)
# new_X = new_X[:,:,mid:-mid, mid:-mid]
f = theano.function([X], new_X)
return f(data)
def LCN(data, kernel_shape):
# X = T.ftensor4()
filter_shape = (1, 1, kernel_shape, kernel_shape)
filters = sharedX(gaussian_filter(kernel_shape).reshape(filter_shape))
convout = conv2d(data, filters=filters, border_mode='full')
# For each pixel, remove mean of 9x9 neighborhood
mid = int(np.floor(kernel_shape/ 2.))
centered_X = data - convout[:,:,mid:-mid,mid:-mid]
# Scale down norm of 9x9 patch if norm is bigger than 1
sum_sqr_XX = conv2d(T.sqr(data), filters=filters, border_mode='full')
denom = T.sqrt(sum_sqr_XX[:,:,mid:-mid,mid:-mid])
per_img_mean = denom.mean(axis = [2,3])
divisor = T.largest(per_img_mean.dimshuffle(0, 1, 'x', 'x'), denom)
new_X = centered_X / T.maximum(1., divisor)
# new_X = new_X[:,:,mid:-mid, mid:-mid]
new_X = T.extra_ops.squeeze(new_X) # remove broadcastable dimension
new_X = new_X[:, 0, :, :] # TODO: check whether this forced squeeze is good
return new_X
def lcn_3d_input(data, kernel_shape, n_maps):
"""
:param data: [examples, depth, filters, height, width]
:param kernel_shape: int
:param n_maps: int
:return: new_x: [examples, depth, filters, height, width]
"""
# create symbolic variable for the input data
ftensor5 = T.TensorType('float32', [False] * 5)
x = ftensor5()
# # determine the number of maps
# n_maps = data.shape[2]
# create 3d filter that spans across all channels / feature maps
# todo: kernel is not really in 3d; need 3d implementation instead of 2d repeated across third dimension
# todo: alternative is to keep 2d kernel and extend short range given data size in z-plane; change first kernel_sh.
filter_shape = (1, kernel_shape[0], n_maps, kernel_shape[1], kernel_shape[2])
filters = np.resize(gaussian_filter(kernel_shape[1]), filter_shape)
filters = filters / np.sum(filters)
filters = sharedX(filters)
# convolve filter with input signal
convolution_out = conv3d(
signals=x,
filters=filters,
signals_shape=data.shape,
filters_shape=filter_shape,
border_mode='valid'
)
# for each pixel, remove mean of 9x9 neighborhood
mid_0 = int(np.floor(kernel_shape[0] / 2.))
mid_1 = int(np.floor(kernel_shape[1] / 2.))
mid_2 = int(np.floor(kernel_shape[2] / 2.))
mean = T.tile(convolution_out, (1, 1, n_maps, 1, 1))
padded_mean = T.zeros_like(x)
padded_mean = T.set_subtensor(padded_mean[:, mid_0:-mid_0, :, mid_1:-mid_1, mid_2:-mid_2], mean)
centered_data = data - padded_mean
# scale down norm of 9x9 patch if norm is bigger than 1
sum_sqr_xx = conv3d(signals=T.sqr(data), filters=filters)
denominator = T.tile(T.sqrt(sum_sqr_xx), (1, 1, n_maps, 1, 1))
padded_denominator = T.ones_like(x)
padded_denominator = T.set_subtensor(
padded_denominator[:, mid_0:-mid_0, :, mid_1:-mid_1, mid_2:-mid_2], denominator
)
per_img_mean = padded_denominator.mean(axis=[1, 2, 3, 4])
divisor = T.largest(
per_img_mean.dimshuffle(0, 'x', 'x', 'x', 'x'),
padded_denominator
)
new_x = centered_data / T.maximum(1., divisor)
# compile theano function
f = theano.function([x], new_x)
return f(data)
def gen_fcn(batch_size,
img_shape,
kernel_size,
data_type='float32',
threshold=1e-4):
'''
generate theano function for doing lecun lcn of a given setting
modified from lecun_lcn in pylearn2.datasets.preprocessing
currently data_type can only be float32
if not, will report error saying input and kernel should be the same type
and kernel type is float32
'''
X = tensor.matrix(dtype=data_type)
X = X.reshape((batch_size, img_shape[0], img_shape[1], 1))
filter_shape = (1, 1, kernel_size, kernel_size)
filters = sharedX(gaussian_filter(kernel_size).reshape(filter_shape))
input_space = Conv2DSpace(shape=img_shape, num_channels=1)
transformer = Conv2D(filters=filters,
batch_size=batch_size,
input_space=input_space,
border_mode='full')
convout = transformer.lmul(X)
# For each pixel, remove mean of 9x9 neighborhood
mid = int(np.floor(kernel_size / 2.))
centered_X = X - convout[:, mid:-mid, mid:-mid, :]
# Scale down norm of 9x9 patch if norm is bigger than 1
transformer = Conv2D(filters=filters,
batch_size=batch_size,
input_space=input_space,
border_mode='full')
sum_sqr_XX = transformer.lmul(X**2)
denom = tensor.sqrt(sum_sqr_XX[:, mid:-mid, mid:-mid, :])
per_img_mean = denom.mean(axis=[1, 2])
divisor = tensor.largest(per_img_mean.dimshuffle(0, 'x', 'x', 1), denom)
divisor = tensor.maximum(divisor, threshold)
new_X = centered_X / divisor
new_X = tensor.flatten(new_X, outdim=3)
f = function([X], new_X)
return f
def lcn_lacombe(data, kernel_shape, n_maps):
# create basic filter that spans all feature maps
filter_shape = (1, n_maps, kernel_shape, kernel_shape)
filters = np.resize(gaussian_filter(kernel_shape), filter_shape)
filters = filters / np.sum(
filters
) # todo: don't scale as this makes input much smaller than weights
filters = sharedX(filters)
# for feature_map in xrange(data.shape[0]):
#
# temp[1, feature_map, :, :] = filters
#
# temp = temp / ml.repmat(np.sum(temp), (1, data.shape[0], kernel_shape, kernel_shape))
# filters = sharedX(temp)
# data = [examples, maps, length, width]; filters = [1, maps, kernel_shape, kernel_shape]
# output = [examples, 1, length - (kernel_shape - 1), width - (kernel_shape - 1)]
convout = conv2d(data, filters=filters, border_mode='full')
# convout = np.reshape(convout, (convout.shape[0], data.shape[1], convout.shape[2], convout.shape[3]))
# For each pixel, remove mean of 9x9 neighborhood
mid = int(np.floor(kernel_shape / 2.))
convout = convout[:, :, mid:-mid, mid:-mid]
centered_X = data - T.tile(convout, (1, n_maps, 1, 1))
# Scale down norm of 9x9 patch if norm is bigger than 1
sum_sqr_XX = conv2d(T.sqr(data), filters=filters, border_mode='full')
denom = T.sqrt(sum_sqr_XX[:, :, mid:-mid, mid:-mid])
per_img_mean = denom.mean(axis=[1, 2, 3])
divisor = T.largest(per_img_mean.dimshuffle(0, 'x', 'x', 'x'),
T.tile(denom, (1, n_maps, 1, 1)))
new_X = centered_X / T.maximum(1., divisor)
# new_X = new_X[:, :, mid:-mid, mid:-mid] # maybe safer to return valid area
return new_X
def lcn_lacombe(data, kernel_shape, n_maps):
# create basic filter that spans all feature maps
filter_shape = (1, n_maps, kernel_shape, kernel_shape)
filters = np.resize(gaussian_filter(kernel_shape), filter_shape)
filters = filters / np.sum(filters) # todo: don't scale as this makes input much smaller than weights
filters = sharedX(filters)
# for feature_map in xrange(data.shape[0]):
#
# temp[1, feature_map, :, :] = filters
#
# temp = temp / ml.repmat(np.sum(temp), (1, data.shape[0], kernel_shape, kernel_shape))
# filters = sharedX(temp)
# data = [examples, maps, length, width]; filters = [1, maps, kernel_shape, kernel_shape]
# output = [examples, 1, length - (kernel_shape - 1), width - (kernel_shape - 1)]
convout = conv2d(data, filters=filters, border_mode='full')
# convout = np.reshape(convout, (convout.shape[0], data.shape[1], convout.shape[2], convout.shape[3]))
# For each pixel, remove mean of 9x9 neighborhood
mid = int(np.floor(kernel_shape / 2.))
convout = convout[:, :, mid:-mid, mid:-mid]
centered_X = data - T.tile(convout, (1, n_maps, 1, 1))
# Scale down norm of 9x9 patch if norm is bigger than 1
sum_sqr_XX = conv2d(T.sqr(data), filters=filters, border_mode='full')
denom = T.sqrt(sum_sqr_XX[:, :, mid:-mid, mid:-mid])
per_img_mean = denom.mean(axis=[1, 2, 3])
divisor = T.largest(per_img_mean.dimshuffle(0, 'x', 'x', 'x'), T.tile(denom, (1, n_maps, 1, 1)))
new_X = centered_X / T.maximum(1., divisor)
# new_X = new_X[:, :, mid:-mid, mid:-mid] # maybe safer to return valid area
return new_X
" image files, but contains " + str(len(paths)))
kernel_shape = 7
from theano import tensor as T
from pylearn2.utils import sharedX
from pylearn2.datasets.preprocessing import gaussian_filter
from theano.tensor.nnet import conv2d
X = T.TensorType(dtype='float32', broadcastable=(True, False, False, True))()
from theano import config
if config.compute_test_value == 'raise':
X.tag.test_value = np.zeros((1, 32, 32, 1), dtype=X.dtype)
orig_X = X
filter_shape = (1, 1, kernel_shape, kernel_shape)
filters = sharedX(gaussian_filter(kernel_shape).reshape(filter_shape))
X = X.dimshuffle(0, 3, 1, 2)
convout = conv2d(X, filters=filters, border_mode='full')
# For each pixel, remove mean of 9x9 neighborhood
mid = int(np.floor(kernel_shape / 2.))
centered_X = X - convout[:, :, mid:-mid, mid:-mid]
# Scale down norm of 9x9 patch if norm is bigger than 1
sum_sqr_XX = conv2d(T.sqr(X), filters=filters, border_mode='full')
denom = T.sqrt(sum_sqr_XX[:, :, mid:-mid, mid:-mid])
per_img_mean = denom.mean(axis=[2, 3])
divisor = T.largest(per_img_mean.dimshuffle(0, 1, 'x', 'x'), denom)
