“““Fairly?basic?set?of?tools?for?real-time?data?augmentation?on?image?data.
Can?easily?be?extended?to?include?new?transformations
new?preprocessing?methods?etc...
based?on?Keras?code
Modified?by?He?Xie?08/2016?Artem?Sevastopolsky?10/2016

For?image?segmentation?problem?data?augmentation.
Transform?train?img?data?and?mask?img?data?simultaneously?and?in?the?same?fashion.
Omit?flow?from?directory?function.
“““


from?__future__?import?absolute_import
from?__future__?import?print_function

import?numpy?as?np
import?re
from?scipy?import?linalg
import?scipy.ndimage?as?ndi
#?from?six.moves?import?range
import?os
import?threading

from?keras?import?backend?as?K


def?random_channel_shift（x?intensity?channel_index=0）:
????x?=?np.rollaxis（x?channel_index?0）
????min_x?max_x?=?np.min（x）?np.max（x）
????channel_images?=?[np.clip（x_channel?+?np.random.uniform（-intensity?intensity）?min_x?max_x）
??????????????????????for?x_channel?in?x]
????x?=?np.stack（channel_images?axis=0）
????x?=?np.rollaxis（x?0?channel_index+1）
????return?x


def?transform_matrix_offset_center（matrix?x?y）:
????o_x?=?float（x）?/?2?+?0.5
????o_y?=?float（y）?/?2?+?0.5
????offset_matrix?=?np.array（[[1?0?o_x]?[0?1?o_y]?[0?0?1]]）
????reset_matrix?=?np.array（[[1?0?-o_x]?[0?1?-o_y]?[0?0?1]]）
????transform_matrix?=?np.dot（np.dot（offset_matrix?matrix）?reset_matrix）
????return?transform_matrix


def?apply_transform（x?transform_matrix?channel_index=0?fill_mode=‘nearest‘?cval=0.）:
????x?=?np.rollaxis（x?channel_index?0）
????final_affine_matrix?=?transform_matrix[:2?:2]
????final_offset?=?transform_matrix[:2?2]
????channel_images?=?[ndi.interpolation.affine_transform（x_channel?final_affine_matrix
??????????????????????final_offset?order=0?mode=fill_mode?cval=cval）?for?x_channel?in?x]
????x?=?np.stack（channel_images?axis=0）
????x?=?np.rollaxis（x?0?channel_index+1）
????return?x


def?flip_axis（x?axis）:
????x?=?np.asarray（x）.swapaxes（axis?0）
????x?=?x[::-1?...]
????x?=?x.swapaxes（0?axis）
????return?x


def?array_to_img（x?dim_ordering=‘default‘?scale=True）:
????from?PIL?import?Image
????if?dim_ordering?==?‘default‘:
????????dim_ordering?=?K.image_dim_ordering（）
????if?dim_ordering?==?‘th‘:
????????x?=?x.transpose（1?2?0）
????if?scale:
????????x?+=?max（-np.min（x）?0）
????????x?/=?np.max（x）
????????x?*=?255
????if?x.shape[2]?==?3:
????????#?RGB
????????return?Image.fromarray（x.astype（‘uint8‘）?‘RGB‘）
????elif?x.shape[2]?==?1:
????????#?grayscale
????????return?Image.fromarray（x[:?:?0].astype（‘uint8‘）?‘L‘）
????else:
????????raise?Exception（‘Unsupported?channel?number:?‘?x.shape[2]）


def?img_to_array（img?dim_ordering=‘default‘）:
????if?dim_ordering?==?‘default‘:
????????dim_ordering?=?K.image_dim_ordering（）
????if?dim_ordering?not?in?[‘th‘?‘tf‘]:
????????raise?Exception（‘Unknown?dim_ordering:?‘?dim_ordering）
????#?image?has?dim_ordering?（height?width?channel）
???