keras/keras_core/applications/convnext.py
2023-05-22 19:13:53 -07:00

753 lines
24 KiB
Python

import numpy as np
from tensorflow.io import gfile
from keras_core import backend
from keras_core import initializers
from keras_core import layers
from keras_core import operations as ops
from keras_core import random
from keras_core.api_export import keras_core_export
from keras_core.applications import imagenet_utils
from keras_core.layers.layer import Layer
from keras_core.models import Functional
from keras_core.models import Sequential
from keras_core.operations import operation_utils
from keras_core.utils import file_utils
BASE_WEIGHTS_PATH = (
"https://storage.googleapis.com/tensorflow/keras-applications/convnext/"
)
WEIGHTS_HASHES = {
"convnext_tiny": (
"8ae6e78ce2933352b1ef4008e6dd2f17bc40771563877d156bc6426c7cf503ff",
"d547c096cabd03329d7be5562c5e14798aa39ed24b474157cef5e85ab9e49ef1",
),
"convnext_small": (
"ce1277d8f1ee5a0ef0e171469089c18f5233860ceaf9b168049cb9263fd7483c",
"6fc8009faa2f00c1c1dfce59feea9b0745eb260a7dd11bee65c8e20843da6eab",
),
"convnext_base": (
"52cbb006d3dadd03f6e095a8ca1aca47aecdd75acb4bc74bce1f5c695d0086e6",
"40a20c5548a5e9202f69735ecc06c990e6b7c9d2de39f0361e27baeb24cb7c45",
),
"convnext_large": (
"070c5ed9ed289581e477741d3b34beffa920db8cf590899d6d2c67fba2a198a6",
"96f02b6f0753d4f543261bc9d09bed650f24dd6bc02ddde3066135b63d23a1cd",
),
"convnext_xlarge": (
"c1f5ccab661354fc3a79a10fa99af82f0fbf10ec65cb894a3ae0815f17a889ee",
"de3f8a54174130e0cecdc71583354753d557fcf1f4487331558e2a16ba0cfe05",
),
}
MODEL_CONFIGS = {
"tiny": {
"depths": [3, 3, 9, 3],
"projection_dims": [96, 192, 384, 768],
"default_size": 224,
},
"small": {
"depths": [3, 3, 27, 3],
"projection_dims": [96, 192, 384, 768],
"default_size": 224,
},
"base": {
"depths": [3, 3, 27, 3],
"projection_dims": [128, 256, 512, 1024],
"default_size": 224,
},
"large": {
"depths": [3, 3, 27, 3],
"projection_dims": [192, 384, 768, 1536],
"default_size": 224,
},
"xlarge": {
"depths": [3, 3, 27, 3],
"projection_dims": [256, 512, 1024, 2048],
"default_size": 224,
},
}
BASE_DOCSTRING = """Instantiates the {name} architecture.
References:
- [A ConvNet for the 2020s](https://arxiv.org/abs/2201.03545)
(CVPR 2022)
For image classification use cases, see
[this page for detailed examples](
https://keras.io/api/applications/#usage-examples-for-image-classification-models).
For transfer learning use cases, make sure to read the
[guide to transfer learning & fine-tuning](
https://keras.io/guides/transfer_learning/).
The `base`, `large`, and `xlarge` models were first pre-trained on the
ImageNet-21k dataset and then fine-tuned on the ImageNet-1k dataset. The
pre-trained parameters of the models were assembled from the
[official repository](https://github.com/facebookresearch/ConvNeXt). To get a
sense of how these parameters were converted to Keras compatible parameters,
please refer to
[this repository](https://github.com/sayakpaul/keras-convnext-conversion).
Note: Each Keras Application expects a specific kind of input preprocessing.
For ConvNeXt, preprocessing is included in the model using a `Normalization`
layer. ConvNeXt models expect their inputs to be float or uint8 tensors of
pixels with values in the [0-255] range.
When calling the `summary()` method after instantiating a ConvNeXt model,
prefer setting the `expand_nested` argument `summary()` to `True` to better
investigate the instantiated model.
Args:
include_top: Whether to include the fully-connected
layer at the top of the network. Defaults to `True`.
weights: One of `None` (random initialization),
`"imagenet"` (pre-training on ImageNet-1k), or the path to the weights
file to be loaded. Defaults to `"imagenet"`.
input_tensor: Optional Keras tensor
(i.e. output of `layers.Input()`)
to use as image input for the model.
input_shape: Optional shape tuple, only to be specified
if `include_top` is `False`.
It should have exactly 3 inputs channels.
pooling: Optional pooling mode for feature extraction
when `include_top` is `False`. Defaults to None.
- `None` means that the output of the model will be
the 4D tensor output of the last convolutional layer.
- `avg` means that global average pooling
will be applied to the output of the
last convolutional layer, and thus
the output of the model will be a 2D tensor.
- `max` means that global max pooling will
be applied.
classes: Optional number of classes to classify images
into, only to be specified if `include_top` is `True`, and
if no `weights` argument is specified. Defaults to 1000 (number of
ImageNet classes).
classifier_activation: A `str` or callable. The activation function to use
on the "top" layer. Ignored unless `include_top=True`. Set
`classifier_activation=None` to return the logits of the "top" layer.
Defaults to `"softmax"`.
When loading pretrained weights, `classifier_activation` can only
be `None` or `"softmax"`.
Returns:
A model instance.
"""
class StochasticDepth(Layer):
"""Stochastic Depth module.
It performs batch-wise dropping rather than sample-wise. In libraries like
`timm`, it's similar to `DropPath` layers that drops residual paths
sample-wise.
References:
- https://github.com/rwightman/pytorch-image-models
Args:
drop_path_rate (float): Probability of dropping paths. Should be within
[0, 1].
Returns:
Tensor either with the residual path dropped or kept.
"""
def __init__(self, drop_path_rate, **kwargs):
super().__init__(**kwargs)
self.drop_path_rate = drop_path_rate
def call(self, x, training=None):
if training:
keep_prob = 1 - self.drop_path_rate
shape = (ops.shape(x)[0],) + (1,) * (len(ops.shape(x)) - 1)
random_tensor = keep_prob + random.uniform(shape, 0, 1)
random_tensor = ops.floor(random_tensor)
return (x / keep_prob) * random_tensor
return x
def get_config(self):
config = super().get_config()
config.update({"drop_path_rate": self.drop_path_rate})
return config
class LayerScale(Layer):
"""Layer scale module.
References:
- https://arxiv.org/abs/2103.17239
Args:
init_values (float): Initial value for layer scale. Should be within
[0, 1].
projection_dim (int): Projection dimensionality.
Returns:
Tensor multiplied to the scale.
"""
def __init__(self, init_values, projection_dim, **kwargs):
super().__init__(**kwargs)
self.init_values = init_values
self.projection_dim = projection_dim
def build(self, _):
self.gamma = self.add_weight(
shape=(self.projection_dim,),
initializer=initializers.Constant(self.init_values),
trainable=True,
)
def call(self, x):
return x * self.gamma
def get_config(self):
config = super().get_config()
config.update(
{
"init_values": self.init_values,
"projection_dim": self.projection_dim,
}
)
return config
def ConvNeXtBlock(
projection_dim, drop_path_rate=0.0, layer_scale_init_value=1e-6, name=None
):
"""ConvNeXt block.
References:
- https://arxiv.org/abs/2201.03545
- https://github.com/facebookresearch/ConvNeXt/blob/main/models/convnext.py
Notes:
In the original ConvNeXt implementation (linked above), the authors use
`Dense` layers for pointwise convolutions for increased efficiency.
Following that, this implementation also uses the same.
Args:
projection_dim (int): Number of filters for convolution layers. In the
ConvNeXt paper, this is referred to as projection dimension.
drop_path_rate (float): Probability of dropping paths. Should be within
[0, 1].
layer_scale_init_value (float): Layer scale value.
Should be a small float number.
name: name to path to the keras layer.
Returns:
A function representing a ConvNeXtBlock block.
"""
if name is None:
name = "prestem" + str(backend.get_uid("prestem"))
def apply(inputs):
x = inputs
x = layers.Conv2D(
filters=projection_dim,
kernel_size=7,
padding="same",
groups=projection_dim,
name=name + "_depthwise_conv",
)(x)
x = layers.LayerNormalization(epsilon=1e-6, name=name + "_layernorm")(x)
x = layers.Dense(4 * projection_dim, name=name + "_pointwise_conv_1")(x)
x = layers.Activation("gelu", name=name + "_gelu")(x)
x = layers.Dense(projection_dim, name=name + "_pointwise_conv_2")(x)
if layer_scale_init_value is not None:
x = LayerScale(
layer_scale_init_value,
projection_dim,
name=name + "_layer_scale",
)(x)
if drop_path_rate:
layer = StochasticDepth(
drop_path_rate, name=name + "_stochastic_depth"
)
else:
layer = layers.Activation("linear", name=name + "_identity")
return inputs + layer(x)
return apply
def PreStem(name=None):
"""Normalizes inputs with ImageNet-1k mean and std."""
if name is None:
name = "prestem" + str(backend.get_uid("prestem"))
def apply(x):
x = layers.Normalization(
mean=[0.485 * 255, 0.456 * 255, 0.406 * 255],
variance=[
(0.229 * 255) ** 2,
(0.224 * 255) ** 2,
(0.225 * 255) ** 2,
],
name=name + "_prestem_normalization",
)(x)
return x
return apply
def Head(num_classes=1000, classifier_activation=None, name=None):
"""Implementation of classification head of ConvNeXt.
Args:
num_classes: number of classes for Dense layer
classifier_activation: activation function for the Dense layer
name: name prefix
Returns:
Classification head function.
"""
if name is None:
name = str(backend.get_uid("head"))
def apply(x):
x = layers.GlobalAveragePooling2D(name=name + "_head_gap")(x)
x = layers.LayerNormalization(
epsilon=1e-6, name=name + "_head_layernorm"
)(x)
x = layers.Dense(
num_classes,
activation=classifier_activation,
name=name + "_head_dense",
)(x)
return x
return apply
def ConvNeXt(
depths,
projection_dims,
drop_path_rate=0.0,
layer_scale_init_value=1e-6,
default_size=224,
model_name="convnext",
include_preprocessing=True,
include_top=True,
weights=None,
input_tensor=None,
input_shape=None,
pooling=None,
classes=1000,
classifier_activation="softmax",
):
"""Instantiates ConvNeXt architecture given specific configuration.
Args:
depths: An iterable containing depths for each individual stages.
projection_dims: An iterable containing output number of channels of
each individual stages.
drop_path_rate: Stochastic depth probability. If 0.0, then stochastic
depth won't be used.
layer_scale_init_value: Layer scale coefficient. If 0.0, layer scaling
won't be used.
default_size: Default input image size.
model_name: An optional name for the model.
include_preprocessing: boolean denoting whther to
include preprocessing in the model.
When `weights="imagenet"` this should always be `True`.
But for other models (e.g., randomly initialized) you should set it
to `False` and apply preprocessing to data accordingly.
include_top: Boolean denoting whether to include classification
head to the model.
weights: one of `None` (random initialization), `"imagenet"`
(pre-training on ImageNet-1k),
or the path to the weights file to be loaded.
input_tensor: optional Keras tensor (i.e. output of `layers.Input()`) to
use as image input for the model.
input_shape: optional shape tuple, only to be specified if `include_top`
is `False`. It should have exactly 3 inputs channels.
pooling: optional pooling mode for feature extraction when `include_top`
is `False`.
- `None` means that the output of the model will be
the 4D tensor output of the last convolutional layer.
- `avg` means that global average pooling will be applied
to the output of the last convolutional layer,
and thus the output of the model will be a 2D tensor.
- `max` means that global max pooling will be applied.
classes: optional number of classes to classify images into,
only to be specified if `include_top` is `True`,
and if no `weights` argument is specified.
classifier_activation: A `str` or callable.
The activation function to use
on the "top" layer. Ignored unless `include_top=True`.
Set `classifier_activation=None` to return the logits
of the "top" layer.
Returns:
A model instance.
"""
if not (weights in {"imagenet", None} or gfile.exists(weights)):
raise ValueError(
"The `weights` argument should be either "
"`None` (random initialization), `imagenet` "
"(pre-training on ImageNet), "
"or the path to the weights file to be loaded."
)
if weights == "imagenet" and include_top and classes != 1000:
raise ValueError(
'If using `weights="imagenet"` with `include_top=True`, '
"`classes` should be 1000. "
f"Received classes={classes}"
)
# Determine proper input shape.
input_shape = imagenet_utils.obtain_input_shape(
input_shape,
default_size=default_size,
min_size=32,
data_format=backend.image_data_format(),
require_flatten=include_top,
weights=weights,
)
if input_tensor is None:
img_input = layers.Input(shape=input_shape)
else:
if not backend.is_keras_tensor(input_tensor):
img_input = layers.Input(tensor=input_tensor, shape=input_shape)
else:
img_input = input_tensor
if input_tensor is not None:
inputs = operation_utils.get_source_inputs(input_tensor)[0]
else:
inputs = img_input
x = inputs
if include_preprocessing:
channel_axis = (
3 if backend.image_data_format() == "channels_last" else 1
)
num_channels = input_shape[channel_axis - 1]
if num_channels == 3:
x = PreStem(name=model_name)(x)
# Stem block.
stem = Sequential(
[
layers.Conv2D(
projection_dims[0],
kernel_size=4,
strides=4,
name=model_name + "_stem_conv",
),
layers.LayerNormalization(
epsilon=1e-6, name=model_name + "_stem_layernorm"
),
],
name=model_name + "_stem",
)
# Downsampling blocks.
downsample_layers = []
downsample_layers.append(stem)
num_downsample_layers = 3
for i in range(num_downsample_layers):
downsample_layer = Sequential(
[
layers.LayerNormalization(
epsilon=1e-6,
name=model_name + "_downsampling_layernorm_" + str(i),
),
layers.Conv2D(
projection_dims[i + 1],
kernel_size=2,
strides=2,
name=model_name + "_downsampling_conv_" + str(i),
),
],
name=model_name + "_downsampling_block_" + str(i),
)
downsample_layers.append(downsample_layer)
# Stochastic depth schedule.
# This is referred from the original ConvNeXt codebase:
# https://github.com/facebookresearch/ConvNeXt/blob/main/models/convnext.py#L86
depth_drop_rates = [
float(x) for x in np.linspace(0.0, drop_path_rate, sum(depths))
]
# First apply downsampling blocks and then apply ConvNeXt stages.
cur = 0
num_convnext_blocks = 4
for i in range(num_convnext_blocks):
x = downsample_layers[i](x)
for j in range(depths[i]):
x = ConvNeXtBlock(
projection_dim=projection_dims[i],
drop_path_rate=depth_drop_rates[cur + j],
layer_scale_init_value=layer_scale_init_value,
name=model_name + f"_stage_{i}_block_{j}",
)(x)
cur += depths[i]
if include_top:
imagenet_utils.validate_activation(classifier_activation, weights)
x = Head(
num_classes=classes,
classifier_activation=classifier_activation,
name=model_name,
)(x)
else:
if pooling == "avg":
x = layers.GlobalAveragePooling2D()(x)
elif pooling == "max":
x = layers.GlobalMaxPooling2D()(x)
x = layers.LayerNormalization(epsilon=1e-6)(x)
model = Functional(inputs=inputs, outputs=x, name=model_name)
# Load weights.
if weights == "imagenet":
if include_top:
file_suffix = ".h5"
file_hash = WEIGHTS_HASHES[model_name][0]
else:
file_suffix = "_notop.h5"
file_hash = WEIGHTS_HASHES[model_name][1]
file_name = model_name + file_suffix
weights_path = file_utils.get_file(
file_name,
BASE_WEIGHTS_PATH + file_name,
cache_subdir="models",
file_hash=file_hash,
)
model.load_weights(weights_path)
elif weights is not None:
model.load_weights(weights)
return model
## Instantiating variants ##
@keras_core_export(
[
"keras_core.applications.convnext.ConvNeXtTiny",
"keras_core.applications.ConvNeXtTiny",
]
)
def ConvNeXtTiny(
model_name="convnext_tiny",
include_top=True,
include_preprocessing=True,
weights="imagenet",
input_tensor=None,
input_shape=None,
pooling=None,
classes=1000,
classifier_activation="softmax",
):
return ConvNeXt(
depths=MODEL_CONFIGS["tiny"]["depths"],
projection_dims=MODEL_CONFIGS["tiny"]["projection_dims"],
drop_path_rate=0.0,
layer_scale_init_value=1e-6,
default_size=MODEL_CONFIGS["tiny"]["default_size"],
model_name=model_name,
include_top=include_top,
include_preprocessing=include_preprocessing,
weights=weights,
input_tensor=input_tensor,
input_shape=input_shape,
pooling=pooling,
classes=classes,
classifier_activation=classifier_activation,
)
@keras_core_export(
[
"keras_core.applications.convnext.ConvNeXtSmall",
"keras_core.applications.ConvNeXtSmall",
]
)
def ConvNeXtSmall(
model_name="convnext_small",
include_top=True,
include_preprocessing=True,
weights="imagenet",
input_tensor=None,
input_shape=None,
pooling=None,
classes=1000,
classifier_activation="softmax",
):
return ConvNeXt(
depths=MODEL_CONFIGS["small"]["depths"],
projection_dims=MODEL_CONFIGS["small"]["projection_dims"],
drop_path_rate=0.0,
layer_scale_init_value=1e-6,
default_size=MODEL_CONFIGS["small"]["default_size"],
model_name=model_name,
include_top=include_top,
include_preprocessing=include_preprocessing,
weights=weights,
input_tensor=input_tensor,
input_shape=input_shape,
pooling=pooling,
classes=classes,
classifier_activation=classifier_activation,
)
@keras_core_export(
[
"keras_core.applications.convnext.ConvNeXtBase",
"keras_core.applications.ConvNeXtBase",
]
)
def ConvNeXtBase(
model_name="convnext_base",
include_top=True,
include_preprocessing=True,
weights="imagenet",
input_tensor=None,
input_shape=None,
pooling=None,
classes=1000,
classifier_activation="softmax",
):
return ConvNeXt(
depths=MODEL_CONFIGS["base"]["depths"],
projection_dims=MODEL_CONFIGS["base"]["projection_dims"],
drop_path_rate=0.0,
layer_scale_init_value=1e-6,
default_size=MODEL_CONFIGS["base"]["default_size"],
model_name=model_name,
include_top=include_top,
include_preprocessing=include_preprocessing,
weights=weights,
input_tensor=input_tensor,
input_shape=input_shape,
pooling=pooling,
classes=classes,
classifier_activation=classifier_activation,
)
@keras_core_export(
[
"keras_core.applications.convnext.ConvNeXtLarge",
"keras_core.applications.ConvNeXtLarge",
]
)
def ConvNeXtLarge(
model_name="convnext_large",
include_top=True,
include_preprocessing=True,
weights="imagenet",
input_tensor=None,
input_shape=None,
pooling=None,
classes=1000,
classifier_activation="softmax",
):
return ConvNeXt(
depths=MODEL_CONFIGS["large"]["depths"],
projection_dims=MODEL_CONFIGS["large"]["projection_dims"],
drop_path_rate=0.0,
layer_scale_init_value=1e-6,
default_size=MODEL_CONFIGS["large"]["default_size"],
model_name=model_name,
include_top=include_top,
include_preprocessing=include_preprocessing,
weights=weights,
input_tensor=input_tensor,
input_shape=input_shape,
pooling=pooling,
classes=classes,
classifier_activation=classifier_activation,
)
@keras_core_export(
[
"keras_core.applications.convnext.ConvNeXtXLarge",
"keras_core.applications.ConvNeXtXLarge",
]
)
def ConvNeXtXLarge(
model_name="convnext_xlarge",
include_top=True,
include_preprocessing=True,
weights="imagenet",
input_tensor=None,
input_shape=None,
pooling=None,
classes=1000,
classifier_activation="softmax",
):
return ConvNeXt(
depths=MODEL_CONFIGS["xlarge"]["depths"],
projection_dims=MODEL_CONFIGS["xlarge"]["projection_dims"],
drop_path_rate=0.0,
layer_scale_init_value=1e-6,
default_size=MODEL_CONFIGS["xlarge"]["default_size"],
model_name=model_name,
include_top=include_top,
include_preprocessing=include_preprocessing,
weights=weights,
input_tensor=input_tensor,
input_shape=input_shape,
pooling=pooling,
classes=classes,
classifier_activation=classifier_activation,
)
ConvNeXtTiny.__doc__ = BASE_DOCSTRING.format(name="ConvNeXtTiny")
ConvNeXtSmall.__doc__ = BASE_DOCSTRING.format(name="ConvNeXtSmall")
ConvNeXtBase.__doc__ = BASE_DOCSTRING.format(name="ConvNeXtBase")
ConvNeXtLarge.__doc__ = BASE_DOCSTRING.format(name="ConvNeXtLarge")
ConvNeXtXLarge.__doc__ = BASE_DOCSTRING.format(name="ConvNeXtXLarge")
@keras_core_export("keras_core.applications.convnext.preprocess_input")
def preprocess_input(x, data_format=None):
"""A placeholder method for backward compatibility.
The preprocessing logic has been included in the convnext model
implementation. Users are no longer required to call this method to
normalize the input data. This method does nothing and only kept as a
placeholder to align the API surface between old and new version of model.
Args:
x: A floating point `numpy.array` or a tensor.
data_format: Optional data format of the image tensor/array. Defaults to
None, in which case the global setting
`keras_core.backend.image_data_format()` is used
(unless you changed it, it defaults to `"channels_last"`).{mode}
Returns:
Unchanged `numpy.array` or tensor.
"""
return x
@keras_core_export("keras_core.applications.convnext.decode_predictions")
def decode_predictions(preds, top=5):
return imagenet_utils.decode_predictions(preds, top=top)
decode_predictions.__doc__ = imagenet_utils.decode_predictions.__doc__