Helper code to untangle tf.image.crop_and_resize when performing a simple crop. Not optimized for speed.

tensorflow_crop.py

"""	
Helper code to untangle tf.image.crop_and_resize when performing a simple crop. Not optimized for speed.

Arguments:
	tf_img  -- Input tensorflow image
	output_size  -- Output size in pixels (w,h)
	crop_yx  -- Top left coordinate of crop, (y,x)
	crop_size -- Size of area to include in crop (w,h)

Returns:
	-- The cropped tensorflow image
"""
def crop_image(tf_img,output_size,crop_yx,crop_size):	

	#tf.image.crop_and_resize's boxes argument 
	#requires inputs in range [0.,1.], hence we normalize
	img_size=tf_img.shape[0:2]+tf_img.shape[0:2]
	a=tf.constant(2*crop_yx)
	b=tf.constant([0,0]+crop_size)
	c=tf.add(a,b)
	boxes=[tf.divide(c,img_size)]

	crop = tf.image.crop_and_resize([tf_img],boxes,[0],output_size)
	return tf.cast(crop, tf.uint8)