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# Copyright (C) 2021-2024, Mindee. | |
# This program is licensed under the Apache License 2.0. | |
# See LICENSE or go to <https://opensource.org/licenses/Apache-2.0> for full license details. | |
from typing import Any, List, Tuple, Union | |
import numpy as np | |
import tensorflow as tf | |
from doctr.models.preprocessor import PreProcessor | |
from doctr.utils.repr import NestedObject | |
from ..core import RecognitionModel | |
from ._utils import remap_preds, split_crops | |
__all__ = ["RecognitionPredictor"] | |
class RecognitionPredictor(NestedObject): | |
"""Implements an object able to identify character sequences in images | |
Args: | |
---- | |
pre_processor: transform inputs for easier batched model inference | |
model: core detection architecture | |
split_wide_crops: wether to use crop splitting for high aspect ratio crops | |
""" | |
_children_names: List[str] = ["pre_processor", "model"] | |
def __init__( | |
self, | |
pre_processor: PreProcessor, | |
model: RecognitionModel, | |
split_wide_crops: bool = True, | |
) -> None: | |
super().__init__() | |
self.pre_processor = pre_processor | |
self.model = model | |
self.split_wide_crops = split_wide_crops | |
self.critical_ar = 8 # Critical aspect ratio | |
self.dil_factor = 1.4 # Dilation factor to overlap the crops | |
self.target_ar = 6 # Target aspect ratio | |
def __call__( | |
self, | |
crops: List[Union[np.ndarray, tf.Tensor]], | |
**kwargs: Any, | |
) -> List[Tuple[str, float]]: | |
if len(crops) == 0: | |
return [] | |
# Dimension check | |
if any(crop.ndim != 3 for crop in crops): | |
raise ValueError("incorrect input shape: all crops are expected to be multi-channel 2D images.") | |
# Split crops that are too wide | |
remapped = False | |
if self.split_wide_crops: | |
new_crops, crop_map, remapped = split_crops(crops, self.critical_ar, self.target_ar, self.dil_factor) | |
if remapped: | |
crops = new_crops | |
# Resize & batch them | |
processed_batches = self.pre_processor(crops) | |
# Forward it | |
raw = [ | |
self.model(batch, return_preds=True, training=False, **kwargs)["preds"] # type: ignore[operator] | |
for batch in processed_batches | |
] | |
# Process outputs | |
out = [charseq for batch in raw for charseq in batch] | |
# Remap crops | |
if self.split_wide_crops and remapped: | |
out = remap_preds(out, crop_map, self.dil_factor) | |
return out | |