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feature_extraction_vilt.py
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feature_extraction_vilt.py
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# coding=utf-8
# Copyright 2022 The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Feature extractor class for ViLT."""
from typing import List, Optional, Union
import numpy as np
from PIL import Image
from ...feature_extraction_utils import BatchFeature, FeatureExtractionMixin
from ...image_utils import (
IMAGENET_STANDARD_MEAN,
IMAGENET_STANDARD_STD,
ImageFeatureExtractionMixin,
ImageInput,
is_torch_tensor,
)
from ...utils import TensorType, is_torch_available, logging
if is_torch_available():
import torch
logger = logging.get_logger(__name__)
class ViltFeatureExtractor(FeatureExtractionMixin, ImageFeatureExtractionMixin):
r"""
Constructs a ViLT feature extractor.
This feature extractor inherits from [`FeatureExtractionMixin`] which contains most of the main methods. Users
should refer to this superclass for more information regarding those methods.
Args:
do_resize (`bool`, *optional*, defaults to `True`):
Whether to resize the input based on `size`.
size (`int`, *optional*, defaults to 384):
Resize the shorter side of the input to the given size. Should be an integer. The longer side will be
limited to under int((1333 / 800) * size) while preserving the aspect ratio. Only has an effect if
`do_resize` is set to `True`.
size_divisor (`int`, *optional*, defaults to 32):
The size by which to make sure both the height and width can be divided.
resample (`int`, *optional*, defaults to `PIL.Image.BICUBIC`):
An optional resampling filter. This can be one of `PIL.Image.NEAREST`, `PIL.Image.BOX`,
`PIL.Image.BILINEAR`, `PIL.Image.HAMMING`, `PIL.Image.BICUBIC` or `PIL.Image.LANCZOS`. Only has an effect
if `do_resize` is set to `True`.
do_normalize (`bool`, *optional*, defaults to `True`):
Whether or not to normalize the input with mean and standard deviation.
image_mean (`List[int]`, defaults to `[0.5, 0.5, 0.5]`):
The sequence of means for each channel, to be used when normalizing images.
image_std (`List[int]`, defaults to `[0.5, 0.5, 0.5]`):
The sequence of standard deviations for each channel, to be used when normalizing images.
"""
model_input_names = ["pixel_values", "pixel_mask"]
def __init__(
self,
do_resize=True,
size=384,
size_divisor=32,
resample=Image.BICUBIC,
do_normalize=True,
image_mean=None,
image_std=None,
**kwargs
):
super().__init__(**kwargs)
self.do_resize = do_resize
self.size = size
self.size_divisor = size_divisor
self.resample = resample
self.do_normalize = do_normalize
self.image_mean = image_mean if image_mean is not None else IMAGENET_STANDARD_MEAN
self.image_std = image_std if image_std is not None else IMAGENET_STANDARD_STD
def _resize(self, image, shorter=800, longer=1333, size_divisor=32, resample=Image.BICUBIC):
"""
Resizes the shorter edge of `image` to `shorter` and limits the longer edge to under `longer`, while preserving
the aspect ratio. Also makes sure that both the height and width can be divided by `size_divisor`.
Based on original implementation:
https://github.com/dandelin/ViLT/blob/3db8b5035464afee84d951bf6322e1b27f1d072d/vilt/transforms/utils.py#L5
Args:
image (`PIL.Image`):
The image to resize.
shorter (`int`, *optional*, defaults to `800`):
The size to which to resize the shorter side of the image.
longer (`int`, *optional*, defaults to `1333`):
The size by which to limit the longer side of the image, while preserving the aspect ratio.
size_divisor (`int`, *optional*, defaults to `32`):
The size by which both the height and the width must be divisible.
resample (`int`, *optional*, defaults to `PIL.Image.BICUBIC`):
An optional resampling filter.
"""
if not isinstance(image, Image.Image):
image = self.to_pil_image(image)
w, h = image.size
min_size = shorter
max_size = longer
scale = min_size / min(w, h)
if h < w:
newh, neww = min_size, scale * w
else:
newh, neww = scale * h, min_size
if max(newh, neww) > max_size:
scale = max_size / max(newh, neww)
newh = newh * scale
neww = neww * scale
newh, neww = int(newh + 0.5), int(neww + 0.5)
newh, neww = newh // size_divisor * size_divisor, neww // size_divisor * size_divisor
return self.resize(image, size=(neww, newh), resample=resample)
def _max_by_axis(self, the_list):
# type: (List[List[int]]) -> List[int]
maxes = the_list[0]
for sublist in the_list[1:]:
for index, item in enumerate(sublist):
maxes[index] = max(maxes[index], item)
return maxes
def pad_and_create_pixel_mask(
self, pixel_values_list: List["torch.Tensor"], return_tensors: Optional[Union[str, TensorType]] = None
):
"""
Pad images up to the largest image in a batch and create a corresponding `pixel_mask`.
Args:
pixel_values_list (`List[torch.Tensor]`):
List of images (pixel values) to be padded. Each image should be a tensor of shape (C, H, W).
return_tensors (`str` or [`~utils.TensorType`], *optional*):
If set, will return tensors instead of NumPy arrays. If set to `'pt'`, return PyTorch `torch.Tensor`
objects.
Returns:
[`BatchFeature`]: A [`BatchFeature`] with the following fields:
- **pixel_values** -- Pixel values to be fed to a model.
- **pixel_mask** -- Pixel mask to be fed to a model (when `pad_and_return_pixel_mask=True` or if
*"pixel_mask"* is in `self.model_input_names`).
"""
max_size = self._max_by_axis([list(image.shape) for image in pixel_values_list])
c, h, w = max_size
padded_images = []
pixel_mask = []
for image in pixel_values_list:
# create padded image
padded_image = np.zeros((c, h, w), dtype=np.float32)
padded_image[: image.shape[0], : image.shape[1], : image.shape[2]] = np.copy(image)
padded_images.append(padded_image)
# create pixel mask
mask = np.zeros((h, w), dtype=np.int64)
mask[: image.shape[1], : image.shape[2]] = True
pixel_mask.append(mask)
# return as BatchFeature
data = {"pixel_values": padded_images, "pixel_mask": pixel_mask}
encoded_inputs = BatchFeature(data=data, tensor_type=return_tensors)
return encoded_inputs
def __call__(
self,
images: ImageInput,
pad_and_return_pixel_mask: Optional[bool] = True,
return_tensors: Optional[Union[str, TensorType]] = None,
**kwargs
) -> BatchFeature:
"""
Main method to prepare for the model one or several image(s).
<Tip warning={true}>
NumPy arrays and PyTorch tensors are converted to PIL images when resizing, so the most efficient is to pass
PIL images.
</Tip>
Args:
images (`PIL.Image.Image`, `np.ndarray`, `torch.Tensor`, `List[PIL.Image.Image]`, `List[np.ndarray]`, `List[torch.Tensor]`):
The image or batch of images to be prepared. Each image can be a PIL image, NumPy array or PyTorch
tensor. In case of a NumPy array/PyTorch tensor, each image should be of shape (C, H, W), where C is a
number of channels, H and W are image height and width.
pad_and_return_pixel_mask (`bool`, *optional*, defaults to `True`):
Whether or not to pad images up to the largest image in a batch and create a pixel mask.
If left to the default, will return a pixel mask that is:
- 1 for pixels that are real (i.e. **not masked**),
- 0 for pixels that are padding (i.e. **masked**).
return_tensors (`str` or [`~utils.TensorType`], *optional*, defaults to `'np'`):
If set, will return tensors of a particular framework. Acceptable values are:
- `'tf'`: Return TensorFlow `tf.constant` objects.
- `'pt'`: Return PyTorch `torch.Tensor` objects.
- `'np'`: Return NumPy `np.ndarray` objects.
- `'jax'`: Return JAX `jnp.ndarray` objects.
Returns:
[`BatchFeature`]: A [`BatchFeature`] with the following fields:
- **pixel_values** -- Pixel values to be fed to a model, of shape (batch_size, num_channels, height,
width).
- **pixel_mask** -- Pixel mask to be fed to a model (when `return_pixel_mask=True` or if *"pixel_mask"* is
in `self.model_input_names`).
"""
# Input type checking for clearer error
valid_images = False
# Check that images has a valid type
if isinstance(images, (Image.Image, np.ndarray)) or is_torch_tensor(images):
valid_images = True
elif isinstance(images, (list, tuple)):
if len(images) == 0 or isinstance(images[0], (Image.Image, np.ndarray)) or is_torch_tensor(images[0]):
valid_images = True
if not valid_images:
raise ValueError(
"Images must of type `PIL.Image.Image`, `np.ndarray` or `torch.Tensor` (single example), "
"`List[PIL.Image.Image]`, `List[np.ndarray]` or `List[torch.Tensor]` (batch of examples)."
)
is_batched = bool(
isinstance(images, (list, tuple))
and (isinstance(images[0], (Image.Image, np.ndarray)) or is_torch_tensor(images[0]))
)
if not is_batched:
images = [images]
# transformations (resizing + normalization)
if self.do_resize and self.size is not None:
longer = int((1333 / 800) * self.size)
images = [
self._resize(
image=image,
shorter=self.size,
longer=longer,
size_divisor=self.size_divisor,
resample=self.resample,
)
for image in images
]
if self.do_normalize:
images = [self.normalize(image=image, mean=self.image_mean, std=self.image_std) for image in images]
if pad_and_return_pixel_mask:
# pad images up to largest image in batch and create pixel_mask
max_size = self._max_by_axis([list(image.shape) for image in images])
c, h, w = max_size
padded_images = []
pixel_mask = []
for image in images:
# create padded image
padded_image = np.zeros((c, h, w), dtype=np.float32)
padded_image[: image.shape[0], : image.shape[1], : image.shape[2]] = np.copy(image)
padded_images.append(padded_image)
# create pixel mask
mask = np.zeros((h, w), dtype=np.int64)
mask[: image.shape[1], : image.shape[2]] = True
pixel_mask.append(mask)
images = padded_images
# return as BatchFeature
data = {}
data["pixel_values"] = images
if pad_and_return_pixel_mask:
data["pixel_mask"] = pixel_mask
encoded_inputs = BatchFeature(data=data, tensor_type=return_tensors)
return encoded_inputs