helpers.py

from math import ceil, floor

import numpy as np
import tensorflow as tf


def get_translate_parameters(index):
    if index == 0: # Translate left 20 percent
        offset = np.array([0.0, 0.2], dtype = np.float32)
        size = np.array([IMAGE_SIZE, ceil(0.8 * IMAGE_SIZE)], dtype = np.int32)
        w_start = 0
        w_end = int(ceil(0.8 * IMAGE_SIZE))
        h_start = 0
        h_end = IMAGE_SIZE
    elif index == 1: # Translate right 20 percent
        offset = np.array([0.0, -0.2], dtype = np.float32)
        size = np.array([IMAGE_SIZE, ceil(0.8 * IMAGE_SIZE)], dtype = np.int32)
        w_start = int(floor((1 - 0.8) * IMAGE_SIZE))
        w_end = IMAGE_SIZE
        h_start = 0
        h_end = IMAGE_SIZE
    elif index == 2: # Translate top 20 percent
        offset = np.array([0.2, 0.0], dtype = np.float32)
        size = np.array([ceil(0.8 * IMAGE_SIZE), IMAGE_SIZE], dtype = np.int32)
        w_start = 0
        w_end = IMAGE_SIZE
        h_start = 0
        h_end = int(ceil(0.8 * IMAGE_SIZE)) 
    else: # Translate bottom 20 percent
        offset = np.array([-0.2, 0.0], dtype = np.float32)
        size = np.array([ceil(0.8 * IMAGE_SIZE), IMAGE_SIZE], dtype = np.int32)
        w_start = 0
        w_end = IMAGE_SIZE
        h_start = int(floor((1 - 0.8) * IMAGE_SIZE))
        h_end = IMAGE_SIZE 
        
    return offset, size, w_start, w_end, h_start, h_end

def translate_images(X_imgs):
    offsets = np.zeros((len(X_imgs), 2), dtype = np.float32)
    n_translations = 4
    X_translated_arr = []
    
    tf.reset_default_graph()
    with tf.Session() as sess:
        sess.run(tf.global_variables_initializer())
        for i in range(n_translations):
            X_translated = np.zeros((len(X_imgs), IMAGE_SIZE, IMAGE_SIZE, 3), 
				    dtype = np.float32)
            X_translated.fill(1.0) # Filling background color
            base_offset, size, w_start, w_end, h_start, h_end = get_translate_parameters(i)
            offsets[:, :] = base_offset 
            glimpses = tf.image.extract_glimpse(X_imgs, size, offsets)
            
            glimpses = sess.run(glimpses)
            X_translated[:, h_start: h_start + size[0], \
			 w_start: w_start + size[1], :] = glimpses
            X_translated_arr.extend(X_translated)
    X_translated_arr = np.array(X_translated_arr, dtype = np.float32)
    return X_translated_arr