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Source code for mmocr.models.textrecog.recognizer.encode_decode_recognizer
# Copyright (c) OpenMMLab. All rights reserved.
import warnings
import torch
from mmocr.models.builder import (RECOGNIZERS, build_backbone, build_convertor,
build_decoder, build_encoder, build_loss,
build_preprocessor)
from .base import BaseRecognizer
[docs]@RECOGNIZERS.register_module()
class EncodeDecodeRecognizer(BaseRecognizer):
"""Base class for encode-decode recognizer."""
def __init__(self,
preprocessor=None,
backbone=None,
encoder=None,
decoder=None,
loss=None,
label_convertor=None,
train_cfg=None,
test_cfg=None,
max_seq_len=40,
pretrained=None,
init_cfg=None):
super().__init__(init_cfg=init_cfg)
# Label convertor (str2tensor, tensor2str)
assert label_convertor is not None
label_convertor.update(max_seq_len=max_seq_len)
self.label_convertor = build_convertor(label_convertor)
# Preprocessor module, e.g., TPS
self.preprocessor = None
if preprocessor is not None:
self.preprocessor = build_preprocessor(preprocessor)
# Backbone
assert backbone is not None
self.backbone = build_backbone(backbone)
# Encoder module
self.encoder = None
if encoder is not None:
self.encoder = build_encoder(encoder)
# Decoder module
assert decoder is not None
decoder.update(num_classes=self.label_convertor.num_classes())
decoder.update(start_idx=self.label_convertor.start_idx)
decoder.update(padding_idx=self.label_convertor.padding_idx)
decoder.update(max_seq_len=max_seq_len)
self.decoder = build_decoder(decoder)
# Loss
assert loss is not None
loss.update(ignore_index=self.label_convertor.padding_idx)
self.loss = build_loss(loss)
self.train_cfg = train_cfg
self.test_cfg = test_cfg
self.max_seq_len = max_seq_len
if pretrained is not None:
warnings.warn('DeprecationWarning: pretrained is a deprecated \
key, please consider using init_cfg')
self.init_cfg = dict(type='Pretrained', checkpoint=pretrained)
[docs] def extract_feat(self, img):
"""Directly extract features from the backbone."""
if self.preprocessor is not None:
img = self.preprocessor(img)
x = self.backbone(img)
return x
[docs] def forward_train(self, img, img_metas):
"""
Args:
img (tensor): Input images of shape (N, C, H, W).
Typically these should be mean centered and std scaled.
img_metas (list[dict]): A list of image info dict where each dict
contains: 'img_shape', 'filename', and may also contain
'ori_shape', and 'img_norm_cfg'.
For details on the values of these keys see
:class:`mmdet.datasets.pipelines.Collect`.
Returns:
dict[str, tensor]: A dictionary of loss components.
"""
for img_meta in img_metas:
valid_ratio = 1.0 * img_meta['resize_shape'][1] / img.size(-1)
img_meta['valid_ratio'] = valid_ratio
feat = self.extract_feat(img)
gt_labels = [img_meta['text'] for img_meta in img_metas]
targets_dict = self.label_convertor.str2tensor(gt_labels)
out_enc = None
if self.encoder is not None:
out_enc = self.encoder(feat, img_metas)
out_dec = self.decoder(
feat, out_enc, targets_dict, img_metas, train_mode=True)
loss_inputs = (
out_dec,
targets_dict,
img_metas,
)
losses = self.loss(*loss_inputs)
return losses
[docs] def simple_test(self, img, img_metas, **kwargs):
"""Test function with test time augmentation.
Args:
imgs (torch.Tensor): Image input tensor.
img_metas (list[dict]): List of image information.
Returns:
list[str]: Text label result of each image.
"""
for img_meta in img_metas:
valid_ratio = 1.0 * img_meta['resize_shape'][1] / img.size(-1)
img_meta['valid_ratio'] = valid_ratio
feat = self.extract_feat(img)
out_enc = None
if self.encoder is not None:
out_enc = self.encoder(feat, img_metas)
out_dec = self.decoder(
feat, out_enc, None, img_metas, train_mode=False)
# early return to avoid post processing
if torch.onnx.is_in_onnx_export():
return out_dec
label_indexes, label_scores = self.label_convertor.tensor2idx(
out_dec, img_metas)
label_strings = self.label_convertor.idx2str(label_indexes)
# flatten batch results
results = []
for string, score in zip(label_strings, label_scores):
results.append(dict(text=string, score=score))
return results
def merge_aug_results(self, aug_results):
out_text, out_score = '', -1
for result in aug_results:
text = result[0]['text']
score = sum(result[0]['score']) / max(1, len(text))
if score > out_score:
out_text = text
out_score = score
out_results = [dict(text=out_text, score=out_score)]
return out_results
[docs] def aug_test(self, imgs, img_metas, **kwargs):
"""Test function as well as time augmentation.
Args:
imgs (list[tensor]): Tensor should have shape NxCxHxW,
which contains all images in the batch.
img_metas (list[list[dict]]): The metadata of images.
"""
aug_results = []
for img, img_meta in zip(imgs, img_metas):
result = self.simple_test(img, img_meta, **kwargs)
aug_results.append(result)
return self.merge_aug_results(aug_results)