def _augment_tile(img_shape,
pos,
tile_shape,
get_tile_func,
augment_params=None,
**kwargs):
'''
fetch tile and augment it
if rotation and shear is activated, a 3 times larger tile
is fetched and the final tile is cut out from that after
rotation/shear.
'''
augment_params = augment_params or {}
rotation_angle = augment_params.get('rotation_angle', 0)
shear_angle = augment_params.get('shear_angle', 0)
pos = np.array(pos)
orig_tile_shape = np.array(tile_shape)
tile_shape = np.array(tile_shape)
augment_fast = (tile_shape[-2:] > 1).any()
augment_slow = augment_fast and (rotation_angle > 0 or shear_angle > 0)
if augment_slow:
pos -= tile_shape
tile_shape *= 3
res = inner_tile_size(img_shape, pos, tile_shape)
pos_transient, size_transient, pos_inside_transient, pad_size = res
tile = get_tile_func(pos=pos_transient, size=size_transient, **kwargs)
tile = np.pad(tile, pad_size, mode='symmetric')
mesh = ut.get_tile_meshgrid(tile.shape, pos_inside_transient, tile_shape)
tile = tile[tuple(mesh)]
if augment_fast:
# if the requested tile is only of size 1 in x and y,
# augmentation can be omitted, since rotation and flipping always
# occurs around the center axis.
rot90 = augment_params.get('rot90', 0)
flipud = augment_params.get('flipud', False)
fliplr = augment_params.get('fliplr', False)
tile = trafo.flip_image_2d_stack(tile, fliplr=fliplr,
flipud=flipud, rot90=rot90)
if augment_slow:
tile = trafo.warp_image_2d_stack(tile, rotation_angle, shear_angle)
mesh = ut.get_tile_meshgrid(tile.shape, orig_tile_shape,
orig_tile_shape)
tile = tile[tuple(mesh)]
return tile
def get_tile_func(pos=None, size=None, img=None):
return img[get_tile_meshgrid(img.shape, pos, size)]