def mean_filter2d(
image: TensorLike,
filter_shape: Union[List[int], Tuple[int], int] = [3, 3],
padding: str = "REFLECT",
constant_values: TensorLike = 0,
name: Optional[str] = None,
) -> tf.Tensor:
"""Perform mean filtering on image(s).
Args:
image: Either a 2-D `Tensor` of shape `[height, width]`,
a 3-D `Tensor` of shape `[height, width, channels]`,
or a 4-D `Tensor` of shape `[batch_size, height, width, channels]`.
filter_shape: An `integer` or `tuple`/`list` of 2 integers, specifying
the height and width of the 2-D mean filter. Can be a single integer
to specify the same value for all spatial dimensions.
padding: A `string`, one of "REFLECT", "CONSTANT", or "SYMMETRIC".
The type of padding algorithm to use, which is compatible with
`mode` argument in `tf.pad`. For more details, please refer to
https://www.tensorflow.org/api_docs/python/tf/pad.
constant_values: A `scalar`, the pad value to use in "CONSTANT"
padding mode.
name: A name for this operation (optional).
Returns:
2-D, 3-D or 4-D `Tensor` of the same dtype as input.
Raises:
ValueError: If `image` is not 2, 3 or 4-dimensional,
if `padding` is other than "REFLECT", "CONSTANT" or "SYMMETRIC",
or if `filter_shape` is invalid.
"""
with tf.name_scope(name or "mean_filter2d"):
image = tf.convert_to_tensor(image, name="image")
original_ndims = img_utils.get_ndims(image)
image = img_utils.to_4D_image(image)
filter_shape = keras_utils.normalize_tuple(filter_shape, 2, "filter_shape")
# Keep the precision if it's float;
# otherwise, convert to float32 for computing.
orig_dtype = image.dtype
if not image.dtype.is_floating:
image = tf.dtypes.cast(image, tf.dtypes.float32)
# Explicitly pad the image
image = _pad(image, filter_shape, mode=padding, constant_values=constant_values)
# Filter of shape (filter_width, filter_height, in_channels, 1)
# has the value of 1 for each element.
area = tf.constant(filter_shape[0] * filter_shape[1], dtype=image.dtype)
filter_shape += (tf.shape(image)[-1], 1)
kernel = tf.ones(shape=filter_shape, dtype=image.dtype)
output = tf.nn.depthwise_conv2d(
image, kernel, strides=(1, 1, 1, 1), padding="VALID"
)
output /= area
output = img_utils.from_4D_image(output, original_ndims)
return tf.dtypes.cast(output, orig_dtype)
def rotate(
images: TensorLike,
angles: TensorLike,
interpolation: str = "nearest",
fill_mode: str = "constant",
name: Optional[str] = None,
fill_value: TensorLike = 0.0,
) -> tf.Tensor:
"""Rotate image(s) counterclockwise by the passed angle(s) in radians.
Args:
images: A tensor of shape
`(num_images, num_rows, num_columns, num_channels)`
(NHWC), `(num_rows, num_columns, num_channels)` (HWC), or
`(num_rows, num_columns)` (HW).
angles: A scalar angle to rotate all images by, or (if `images` has rank 4)
a vector of length num_images, with an angle for each image in the
batch.
interpolation: Interpolation mode. Supported values: "nearest",
"constant".
fill_mode: Points outside the boundaries of the input are filled according
to the given mode (one of `{'constant', 'reflect', 'wrap', 'nearest'}`).
- *reflect*: `(d c b a | a b c d | d c b a)`
The input is extended by reflecting about the edge of the last pixel.
- *constant*: `(k k k k | a b c d | k k k k)`
The input is extended by filling all values beyond the edge with the
same constant value k = 0.
- *wrap*: `(a b c d | a b c d | a b c d)`
The input is extended by wrapping around to the opposite edge.
- *nearest*: `(a a a a | a b c d | d d d d)`
The input is extended by the nearest pixel.
fill_value: a float represents the value to be filled outside the
boundaries when `fill_mode` is "constant".
name: The name of the op.
Returns:
Image(s) with the same type and shape as `images`, rotated by the given
angle(s). Empty space due to the rotation will be filled with zeros.
Raises:
TypeError: If `images` is an invalid type.
"""
with tf.name_scope(name or "rotate"):
image_or_images = tf.convert_to_tensor(images)
if image_or_images.dtype.base_dtype not in _IMAGE_DTYPES:
raise TypeError("Invalid dtype %s." % image_or_images.dtype)
images = img_utils.to_4D_image(image_or_images)
original_ndims = img_utils.get_ndims(image_or_images)
image_height = tf.cast(tf.shape(images)[1], tf.dtypes.float32)[None]
image_width = tf.cast(tf.shape(images)[2], tf.dtypes.float32)[None]
output = transform(
images,
angles_to_projective_transforms(angles, image_height, image_width),
interpolation=interpolation,
fill_mode=fill_mode,
fill_value=fill_value,
)
return img_utils.from_4D_image(output, original_ndims)
def euclidean_dist_transform(
images: TensorLike,
dtype: Type[tf.dtypes.DType] = tf.float32,
name: Optional[str] = None,
) -> tf.Tensor:
"""Applies euclidean distance transform(s) to the image(s).
Args:
images: A tensor of shape `(num_images, num_rows, num_columns, 1)`
(NHWC), or `(num_rows, num_columns, 1)` (HWC) or
`(num_rows, num_columns)` (HW).
dtype: `tf.dtypes.DType` of the output tensor.
name: The name of the op.
Returns:
Image(s) with the type `dtype` and same shape as `images`, with the
transform applied. If a tensor of all ones is given as input, the
output tensor will be filled with the max value of the `dtype`.
Raises:
TypeError: If `image` is not tf.uint8, or `dtype` is not floating point.
ValueError: If `image` more than one channel, or `image` is not of
rank between 2 and 4.
"""
with tf.name_scope(name or "euclidean_distance_transform"):
image_or_images = tf.convert_to_tensor(images, name="images")
if image_or_images.dtype.base_dtype != tf.uint8:
raise TypeError("Invalid dtype %s. Expected uint8." %
image_or_images.dtype)
images = img_utils.to_4D_image(image_or_images)
original_ndims = img_utils.get_ndims(image_or_images)
if images.get_shape()[3] != 1 and images.get_shape()[3] is not None:
raise ValueError("`images` must have only one channel")
if dtype not in [tf.float16, tf.float32, tf.float64]:
raise TypeError("`dtype` must be float16, float32 or float64")
images = tf.cast(images, dtype)
output = _image_so.ops.addons_euclidean_distance_transform(images)
return img_utils.from_4D_image(output, original_ndims)
def euclidean_dist_transform(
images: TensorLike,
dtype: Type[tf.dtypes.DType] = tf.float32,
name: Optional[str] = None,
) -> tf.Tensor:
"""Applies euclidean distance transform(s) to the image(s).
Based on [Distance Transforms of Sampled Functions]
(http://www.theoryofcomputing.org/articles/v008a019/v008a019.pdf).
Args:
images: A tensor of shape `(num_images, num_rows, num_columns, num_channels)`
(NHWC), or `(num_rows, num_columns, num_channels)` (HWC) or
`(num_rows, num_columns)` (HW).
dtype: `tf.dtypes.DType` of the output tensor.
name: The name of the op.
Returns:
Image(s) with the type `dtype` and same shape as `images`, with the
transform applied. If a tensor of all ones is given as input, the
output tensor will be filled with the max value of the `dtype`.
Raises:
TypeError: If `image` is not tf.uint8, or `dtype` is not floating point.
"""
with tf.name_scope(name or "euclidean_distance_transform"):
image_or_images = tf.convert_to_tensor(images, name="images")
if image_or_images.dtype.base_dtype != tf.uint8:
raise TypeError("Invalid dtype %s. Expected uint8." %
image_or_images.dtype)
images = img_utils.to_4D_image(image_or_images)
original_ndims = img_utils.get_ndims(image_or_images)
if dtype not in [tf.float16, tf.float32, tf.float64]:
raise TypeError("`dtype` must be float16, float32 or float64")
output = _image_so.ops.addons_euclidean_distance_transform(
images, dtype)
return img_utils.from_4D_image(output, original_ndims)
def rotate(
images: TensorLike,
angles: TensorLike,
interpolation: str = "NEAREST",
name: Optional[str] = None,
) -> tf.Tensor:
"""Rotate image(s) counterclockwise by the passed angle(s) in radians.
Args:
images: A tensor of shape
`(num_images, num_rows, num_columns, num_channels)`
(NHWC), `(num_rows, num_columns, num_channels)` (HWC), or
`(num_rows, num_columns)` (HW).
angles: A scalar angle to rotate all images by, or (if `images` has rank 4)
a vector of length num_images, with an angle for each image in the
batch.
interpolation: Interpolation mode. Supported values: "NEAREST",
"BILINEAR".
name: The name of the op.
Returns:
Image(s) with the same type and shape as `images`, rotated by the given
angle(s). Empty space due to the rotation will be filled with zeros.
Raises:
TypeError: If `images` is an invalid type.
"""
with tf.name_scope(name or "rotate"):
image_or_images = tf.convert_to_tensor(images)
if image_or_images.dtype.base_dtype not in _IMAGE_DTYPES:
raise TypeError("Invalid dtype %s." % image_or_images.dtype)
images = img_utils.to_4D_image(image_or_images)
original_ndims = img_utils.get_ndims(image_or_images)
image_height = tf.cast(tf.shape(images)[1], tf.dtypes.float32)[None]
image_width = tf.cast(tf.shape(images)[2], tf.dtypes.float32)[None]
output = transform(
images,
angles_to_projective_transforms(angles, image_height, image_width),
interpolation=interpolation,
)
return img_utils.from_4D_image(output, original_ndims)
def transform(
images: TensorLike,
transforms: TensorLike,
interpolation: str = "NEAREST",
output_shape: Optional[list] = None,
name: Optional[str] = None,
) -> tf.Tensor:
"""Applies the given transform(s) to the image(s).
Args:
images: A tensor of shape (num_images, num_rows, num_columns,
num_channels) (NHWC), (num_rows, num_columns, num_channels) (HWC), or
(num_rows, num_columns) (HW).
transforms: Projective transform matrix/matrices. A vector of length 8 or
tensor of size N x 8. If one row of transforms is
[a0, a1, a2, b0, b1, b2, c0, c1], then it maps the *output* point
`(x, y)` to a transformed *input* point
`(x', y') = ((a0 x + a1 y + a2) / k, (b0 x + b1 y + b2) / k)`,
where `k = c0 x + c1 y + 1`. The transforms are *inverted* compared to
the transform mapping input points to output points. Note that
gradients are not backpropagated into transformation parameters.
interpolation: Interpolation mode.
Supported values: "NEAREST", "BILINEAR".
output_shape: Output dimesion after the transform, [height, width].
If None, output is the same size as input image.
name: The name of the op.
Returns:
Image(s) with the same type and shape as `images`, with the given
transform(s) applied. Transformed coordinates outside of the input image
will be filled with zeros.
Raises:
TypeError: If `image` is an invalid type.
ValueError: If output shape is not 1-D int32 Tensor.
"""
with tf.name_scope(name or "transform"):
image_or_images = tf.convert_to_tensor(images, name="images")
transform_or_transforms = tf.convert_to_tensor(transforms,
name="transforms",
dtype=tf.dtypes.float32)
if image_or_images.dtype.base_dtype not in _IMAGE_DTYPES:
raise TypeError("Invalid dtype %s." % image_or_images.dtype)
images = img_utils.to_4D_image(image_or_images)
original_ndims = img_utils.get_ndims(image_or_images)
if output_shape is None:
output_shape = tf.shape(images)[1:3]
output_shape = tf.convert_to_tensor(output_shape,
tf.dtypes.int32,
name="output_shape")
if not output_shape.get_shape().is_compatible_with([2]):
raise ValueError(
"output_shape must be a 1-D Tensor of 2 elements: "
"new_height, new_width")
if len(transform_or_transforms.get_shape()) == 1:
transforms = transform_or_transforms[None]
elif transform_or_transforms.get_shape().ndims is None:
raise ValueError("transforms rank must be statically known")
elif len(transform_or_transforms.get_shape()) == 2:
transforms = transform_or_transforms
else:
transforms = transform_or_transforms
raise ValueError(
"transforms should have rank 1 or 2, but got rank %d" %
len(transforms.get_shape()))
output = tf.raw_ops.ImageProjectiveTransformV2(
images=images,
transforms=transforms,
output_shape=output_shape,
interpolation=interpolation.upper(),
)
return img_utils.from_4D_image(output, original_ndims)
def transform(
images: TensorLike,
transforms: TensorLike,
interpolation: str = "nearest",
fill_mode: str = "constant",
output_shape: Optional[list] = None,
name: Optional[str] = None,
fill_value: TensorLike = 0.0,
) -> tf.Tensor:
"""Applies the given transform(s) to the image(s).
Args:
images: A tensor of shape (num_images, num_rows, num_columns,
num_channels) (NHWC), (num_rows, num_columns, num_channels) (HWC), or
(num_rows, num_columns) (HW).
transforms: Projective transform matrix/matrices. A vector of length 8 or
tensor of size N x 8. If one row of transforms is
[a0, a1, a2, b0, b1, b2, c0, c1], then it maps the *output* point
`(x, y)` to a transformed *input* point
`(x', y') = ((a0 x + a1 y + a2) / k, (b0 x + b1 y + b2) / k)`,
where `k = c0 x + c1 y + 1`. The transforms are *inverted* compared to
the transform mapping input points to output points. Note that
gradients are not backpropagated into transformation parameters.
interpolation: Interpolation mode.
Supported values: "nearest", "bilinear".
fill_mode: Points outside the boundaries of the input are filled according
to the given mode (one of `{'constant', 'reflect', 'wrap', 'nearest'}`).
- *reflect*: `(d c b a | a b c d | d c b a)`
The input is extended by reflecting about the edge of the last pixel.
- *constant*: `(k k k k | a b c d | k k k k)`
The input is extended by filling all values beyond the edge with the
same constant value k = 0.
- *wrap*: `(a b c d | a b c d | a b c d)`
The input is extended by wrapping around to the opposite edge.
- *nearest*: `(a a a a | a b c d | d d d d)`
The input is extended by the nearest pixel.
fill_value: a float represents the value to be filled outside the
boundaries when `fill_mode` is "constant".
output_shape: Output dimesion after the transform, [height, width].
If None, output is the same size as input image.
name: The name of the op.
Returns:
Image(s) with the same type and shape as `images`, with the given
transform(s) applied. Transformed coordinates outside of the input image
will be filled with zeros.
Raises:
TypeError: If `image` is an invalid type.
ValueError: If output shape is not 1-D int32 Tensor.
"""
with tf.name_scope(name or "transform"):
image_or_images = tf.convert_to_tensor(images, name="images")
transform_or_transforms = tf.convert_to_tensor(transforms,
name="transforms",
dtype=tf.dtypes.float32)
if image_or_images.dtype.base_dtype not in _IMAGE_DTYPES:
raise TypeError("Invalid dtype %s." % image_or_images.dtype)
images = img_utils.to_4D_image(image_or_images)
original_ndims = img_utils.get_ndims(image_or_images)
if output_shape is None:
output_shape = tf.shape(images)[1:3]
output_shape = tf.convert_to_tensor(output_shape,
tf.dtypes.int32,
name="output_shape")
if not output_shape.get_shape().is_compatible_with([2]):
raise ValueError(
"output_shape must be a 1-D Tensor of 2 elements: "
"new_height, new_width")
if len(transform_or_transforms.get_shape()) == 1:
transforms = transform_or_transforms[None]
elif transform_or_transforms.get_shape().ndims is None:
raise ValueError("transforms rank must be statically known")
elif len(transform_or_transforms.get_shape()) == 2:
transforms = transform_or_transforms
else:
transforms = transform_or_transforms
raise ValueError(
"transforms should have rank 1 or 2, but got rank %d" %
len(transforms.get_shape()))
if LooseVersion(tf.__version__) >= LooseVersion("2.4.0"):
fill_value = tf.convert_to_tensor(fill_value,
dtype=tf.float32,
name="fill_value")
output = tf.raw_ops.ImageProjectiveTransformV3(
images=images,
transforms=transforms,
output_shape=output_shape,
interpolation=interpolation.upper(),
fill_mode=fill_mode.upper(),
fill_value=fill_value,
)
else:
fill_mode = fill_mode.upper()
# TODO(WindQAQ): Get rid of the check once we drop TensorFlow < 2.4 support.
if fill_mode == "CONSTANT":
warnings.warn(
"fill_value is not supported and is always 0 for TensorFlow < 2.4.0."
)
if fill_mode == "NEAREST":
raise ValueError(
"NEAREST fill_mode is not supported for TensorFlow < 2.4.0."
)
output = tf.raw_ops.ImageProjectiveTransformV2(
images=images,
transforms=transforms,
output_shape=output_shape,
interpolation=interpolation.upper(),
fill_mode=fill_mode,
)
return img_utils.from_4D_image(output, original_ndims)
def median_filter2d(image,
filter_shape=(3, 3),
padding="REFLECT",
constant_values=0,
name=None):
"""Perform median filtering on image(s).
Args:
image: Either a 2-D `Tensor` of shape `[height, width]`,
a 3-D `Tensor` of shape `[height, width, channels]`,
or a 4-D `Tensor` of shape `[batch_size, height, width, channels]`.
filter_shape: An `integer` or `tuple`/`list` of 2 integers, specifying
the height and width of the 2-D median filter. Can be a single integer
to specify the same value for all spatial dimensions.
padding: A `string`, one of "REFLECT", "CONSTANT", or "SYMMETRIC".
The type of padding algorithm to use, which is compatible with
`mode` argument in `tf.pad`. For more details, please refer to
https://www.tensorflow.org/api_docs/python/tf/pad.
constant_values: A `scalar`, the pad value to use in "CONSTANT"
padding mode.
name: A name for this operation (optional).
Returns:
3-D or 4-D `Tensor` of the same dtype as input.
Raises:
ValueError: If `image` is not 2, 3 or 4-dimensional,
if `padding` is other than "REFLECT", "CONSTANT" or "SYMMETRIC",
or if `filter_shape` is invalid.
"""
with tf.name_scope(name or "median_filter2d"):
image = tf.convert_to_tensor(image, name="image")
original_ndims = img_utils.get_ndims(image)
image = img_utils.to_4D_image(image)
if padding not in ["REFLECT", "CONSTANT", "SYMMETRIC"]:
raise ValueError(
"padding should be one of \"REFLECT\", \"CONSTANT\", or "
"\"SYMMETRIC\".")
filter_shape = keras_utils.normalize_tuple(filter_shape, 2,
"filter_shape")
image_shape = tf.shape(image)
batch_size = image_shape[0]
height = image_shape[1]
width = image_shape[2]
channels = image_shape[3]
# Explicitly pad the image
image = _pad(image,
filter_shape,
mode=padding,
constant_values=constant_values)
area = filter_shape[0] * filter_shape[1]
floor = (area + 1) // 2
ceil = area // 2 + 1
patches = tf.image.extract_patches(
image,
sizes=[1, filter_shape[0], filter_shape[1], 1],
strides=[1, 1, 1, 1],
rates=[1, 1, 1, 1],
padding="VALID")
patches = tf.reshape(patches,
shape=[batch_size, height, width, area, channels])
patches = tf.transpose(patches, [0, 1, 2, 4, 3])
# Note the returned median is casted back to the original type
# Take [5, 6, 7, 8] for example, the median is (6 + 7) / 2 = 3.5
# It turns out to be int(6.5) = 6 if the original type is int
top = tf.nn.top_k(patches, k=ceil).values
if area % 2 == 1:
median = top[:, :, :, :, floor - 1]
else:
median = (top[:, :, :, :, floor - 1] +
top[:, :, :, :, ceil - 1]) / 2
output = tf.cast(median, image.dtype)
output = img_utils.from_4D_image(output, original_ndims)
return output
def gaussian_filter2d(
image: TensorLike,
filter_shape: Union[List[int], Tuple[int], int] = [3, 3],
sigma: Union[List[float], Tuple[float], float] = 1.0,
padding: str = "REFLECT",
constant_values: TensorLike = 0,
name: Optional[str] = None,
) -> TensorLike:
"""Perform Gaussian blur on image(s).
Args:
image: Either a 2-D `Tensor` of shape `[height, width]`,
a 3-D `Tensor` of shape `[height, width, channels]`,
or a 4-D `Tensor` of shape `[batch_size, height, width, channels]`.
filter_shape: An `integer` or `tuple`/`list` of 2 integers, specifying
the height and width of the 2-D gaussian filter. Can be a single
integer to specify the same value for all spatial dimensions.
sigma: A `float` or `tuple`/`list` of 2 floats, specifying
the standard deviation in x and y direction the 2-D gaussian filter.
Can be a single float to specify the same value for all spatial
dimensions.
padding: A `string`, one of "REFLECT", "CONSTANT", or "SYMMETRIC".
The type of padding algorithm to use, which is compatible with
`mode` argument in `tf.pad`. For more details, please refer to
https://www.tensorflow.org/api_docs/python/tf/pad.
constant_values: A `scalar`, the pad value to use in "CONSTANT"
padding mode.
name: A name for this operation (optional).
Returns:
2-D, 3-D or 4-D `Tensor` of the same dtype as input.
Raises:
ValueError: If `image` is not 2, 3 or 4-dimensional,
if `padding` is other than "REFLECT", "CONSTANT" or "SYMMETRIC",
if `filter_shape` is invalid,
or if `sigma` is invalid.
"""
with tf.name_scope(name or "gaussian_filter2d"):
if isinstance(sigma, (list, tuple)):
if len(sigma) != 2:
raise ValueError(
"sigma should be a float or a tuple/list of 2 floats")
else:
sigma = (sigma, ) * 2
if any(s < 0 for s in sigma):
raise ValueError("sigma should be greater than or equal to 0.")
image = tf.convert_to_tensor(image, name="image")
sigma = tf.convert_to_tensor(sigma, name="sigma")
original_ndims = img_utils.get_ndims(image)
image = img_utils.to_4D_image(image)
# Keep the precision if it's float;
# otherwise, convert to float32 for computing.
orig_dtype = image.dtype
if not image.dtype.is_floating:
image = tf.cast(image, tf.float32)
channels = tf.shape(image)[3]
filter_shape = keras_utils.normalize_tuple(filter_shape, 2,
"filter_shape")
sigma = tf.cast(sigma, image.dtype)
gaussian_kernel_x = _get_gaussian_kernel(sigma[1], filter_shape[1])
gaussian_kernel_x = gaussian_kernel_x[tf.newaxis, :]
gaussian_kernel_y = _get_gaussian_kernel(sigma[0], filter_shape[0])
gaussian_kernel_y = gaussian_kernel_y[:, tf.newaxis]
gaussian_kernel_2d = _get_gaussian_kernel_2d(gaussian_kernel_y,
gaussian_kernel_x)
gaussian_kernel_2d = gaussian_kernel_2d[:, :, tf.newaxis, tf.newaxis]
gaussian_kernel_2d = tf.tile(gaussian_kernel_2d, [1, 1, channels, 1])
image = _pad(image,
filter_shape,
mode=padding,
constant_values=constant_values)
output = tf.nn.depthwise_conv2d(
input=image,
filter=gaussian_kernel_2d,
strides=(1, 1, 1, 1),
padding="VALID",
)
output = img_utils.from_4D_image(output, original_ndims)
return tf.cast(output, orig_dtype)
def sparse_image_warp(
image: TensorLike,
source_control_point_locations: TensorLike,
dest_control_point_locations: TensorLike,
interpolation_order: int = 2,
regularization_weight: FloatTensorLike = 0.0,
num_boundary_points: int = 0,
name: str = "sparse_image_warp",
) -> tf.Tensor:
"""Image warping using correspondences between sparse control points.
Apply a non-linear warp to the image, where the warp is specified by
the source and destination locations of a (potentially small) number of
control points. First, we use a polyharmonic spline
(`tfa.image.interpolate_spline`) to interpolate the displacements
between the corresponding control points to a dense flow field.
Then, we warp the image using this dense flow field
(`tfa.image.dense_image_warp`).
Let t index our control points. For `regularization_weight = 0`, we have:
warped_image[b, dest_control_point_locations[b, t, 0],
dest_control_point_locations[b, t, 1], :] =
image[b, source_control_point_locations[b, t, 0],
source_control_point_locations[b, t, 1], :].
For `regularization_weight > 0`, this condition is met approximately, since
regularized interpolation trades off smoothness of the interpolant vs.
reconstruction of the interpolant at the control points.
See `tfa.image.interpolate_spline` for further documentation of the
`interpolation_order` and `regularization_weight` arguments.
Args:
image: Either a 2-D float `Tensor` of shape `[height, width]`,
a 3-D `Tensor` of shape `[height, width, channels]`,
or a 4-D `Tensor` of shape `[batch_size, height, width, channels]`.
`batch_size` is assumed as one when `image` is a 2-D or 3-D `Tensor`.
source_control_point_locations: `[batch_size, num_control_points, 2]` float
`Tensor`.
dest_control_point_locations: `[batch_size, num_control_points, 2]` float
`Tensor`.
interpolation_order: polynomial order used by the spline interpolation
regularization_weight: weight on smoothness regularizer in interpolation
num_boundary_points: How many zero-flow boundary points to include at
each image edge. Usage:
- `num_boundary_points=0`: don't add zero-flow points
- `num_boundary_points=1`: 4 corners of the image
- `num_boundary_points=2`: 4 corners and one in the middle of each edge
(8 points total)
- `num_boundary_points=n`: 4 corners and n-1 along each edge
name: A name for the operation (optional).
Note that `image` and `offsets` can be of type `tf.half`, `tf.float32`, or
`tf.float64`, and do not necessarily have to be the same type.
Returns:
warped_image: a float `Tensor` with the same shape and dtype as `image`.
flow_field: `[batch_size, height, width, 2]` float `Tensor` containing the
dense flow field produced by the interpolation.
"""
image = tf.convert_to_tensor(image)
original_ndims = img_utils.get_ndims(image)
image = img_utils.to_4D_image(image)
source_control_point_locations = tf.convert_to_tensor(
source_control_point_locations)
dest_control_point_locations = tf.convert_to_tensor(
dest_control_point_locations)
control_point_flows = dest_control_point_locations - source_control_point_locations
clamp_boundaries = num_boundary_points > 0
boundary_points_per_edge = num_boundary_points - 1
with tf.name_scope(name or "sparse_image_warp"):
image_shape = tf.shape(image)
batch_size, image_height, image_width = (
image_shape[0],
image_shape[1],
image_shape[2],
)
# This generates the dense locations where the interpolant
# will be evaluated.
grid_locations = _get_grid_locations(image_height, image_width)
flattened_grid_locations = tf.reshape(grid_locations,
[image_height * image_width, 2])
flattened_grid_locations = tf.cast(
_expand_to_minibatch(flattened_grid_locations, batch_size),
image.dtype)
if clamp_boundaries:
(
dest_control_point_locations,
control_point_flows,
) = _add_zero_flow_controls_at_boundary(
dest_control_point_locations,
control_point_flows,
image_height,
image_width,
boundary_points_per_edge,
)
flattened_flows = interpolate_spline(
dest_control_point_locations,
control_point_flows,
flattened_grid_locations,
interpolation_order,
regularization_weight,
)
dense_flows = tf.reshape(flattened_flows,
[batch_size, image_height, image_width, 2])
warped_image = dense_image_warp(image, dense_flows)
return img_utils.from_4D_image(warped_image,
original_ndims), dense_flows
def gaussian_filter2d(
image: FloatTensorLike,
filter_shape: Union[List[int], Tuple[int]] = [3, 3],
sigma: FloatTensorLike = 1,
padding: str = "REFLECT",
constant_values: TensorLike = 0,
name: Optional[str] = None,
) -> FloatTensorLike:
"""Perform Gaussian blur on image(s).
Args:
image: Either a 2-D `Tensor` of shape `[height, width]`,
a 3-D `Tensor` of shape `[height, width, channels]`,
or a 4-D `Tensor` of shape `[batch_size, height, width, channels]`.
filter_shape: An `integer` or `tuple`/`list` of 2 integers, specifying
the height and width of the 2-D gaussian filter. Can be a single
integer to specify the same value for all spatial dimensions.
sigma: Standard deviation of Gaussian.
padding: A `string`, one of "REFLECT", "CONSTANT", or "SYMMETRIC".
The type of padding algorithm to use, which is compatible with
`mode` argument in `tf.pad`. For more details, please refer to
https://www.tensorflow.org/api_docs/python/tf/pad.
constant_values: A `scalar`, the pad value to use in "CONSTANT"
padding mode.
name: A name for this operation (optional).
Returns:
2-D, 3-D or 4-D `Tensor` of the same dtype as input.
Raises:
ValueError: If `image` is not 2, 3 or 4-dimensional,
if `padding` is other than "REFLECT", "CONSTANT" or "SYMMETRIC",
if `filter_shape` is invalid,
or if `sigma` is less than or equal to 0.
"""
with tf.name_scope(name or "gaussian_filter2d"):
if sigma <= 0:
raise ValueError("Sigma should not be zero")
if padding not in ["REFLECT", "CONSTANT", "SYMMETRIC"]:
raise ValueError(
"Padding should be REFLECT, CONSTANT, OR SYMMETRIC")
image = tf.cast(image, tf.float32)
original_ndims = img_utils.get_ndims(image)
image = img_utils.to_4D_image(image)
channels = tf.shape(image)[3]
filter_shape = keras_utils.normalize_tuple(filter_shape, 2,
"filter_shape")
gaussian_filter_x = _get_gaussian_kernel(sigma, filter_shape[1])
gaussian_filter_x = tf.cast(gaussian_filter_x, tf.float32)
gaussian_filter_x = tf.reshape(gaussian_filter_x, [1, filter_shape[1]])
gaussian_filter_y = _get_gaussian_kernel(sigma, filter_shape[0])
gaussian_filter_y = tf.reshape(gaussian_filter_y, [filter_shape[0], 1])
gaussian_filter_y = tf.cast(gaussian_filter_y, tf.float32)
gaussian_filter_2d = _get_gaussian_kernel_2d(gaussian_filter_y,
gaussian_filter_x)
gaussian_filter_2d = tf.repeat(gaussian_filter_2d, channels)
gaussian_filter_2d = tf.reshape(
gaussian_filter_2d,
[filter_shape[0], filter_shape[1], channels, 1])
image = _pad(
image,
filter_shape,
mode=padding,
constant_values=constant_values,
)
output = tf.nn.depthwise_conv2d(
input=image,
filter=gaussian_filter_2d,
strides=(1, 1, 1, 1),
padding="VALID",
)
output = img_utils.from_4D_image(output, original_ndims)
return output