对OCR模型CNN-CTC的鲁棒性评测

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概述

本教程主要演示利用自然扰动serving服务,对OCR模型CNN-CTC做一个简单的鲁棒性评测。先基于serving生成多种自然扰动样本数据集,然后根据CNN-CTC模型在自然扰动样本数据集上的表现来评估模型的鲁棒性。

你可以在这里找到完整可运行的样例代码:https://gitee.com/mindspore/mindarmour/tree/master/examples/natural_robustness/ocr_evaluate

环境要求

  • 硬件

    • Ascend或GPU处理器搭建硬件环境。

  • 依赖

    • MindSpore

    • MindSpore-Serving >= 1.6.0

    • MindArmour

脚本说明

代码结构

|-- natural_robustness
    |-- serving                         # 提供自然扰动样本生成的serving服务
    |-- ocr_evaluate
        |-- cnn_ctc                     # cnn_ctc模型目录:模型的训练、推理、前后处理
        |-- data                        # 存储实验分析数据
        |-- default_config.yaml         # 参数配置
        |-- generate_adv_samples.py     # 用于生成自然扰动样本
        |-- eval_and_save.py            # cnn_ctc在扰动样本上推理,并保存推理结果
        |-- analyse.py                  # 分析cnn_ctc模型的鲁棒性

脚本参数

default_config.yaml中可以同时配置训练参数、推理参数、鲁棒性评测参数。这里我们重点关注在评测过程中使用到的参数,以及需要用户配置的参数,其余参数说明参考CNN-CTC教程

  • --TEST_DATASET_PATH:测试数据集路径。

  • --CHECKPOINT_PATH:checkpoint路径。

  • --ADV_TEST_DATASET_PATH:扰动样本数据集路径。

  • --IS_ADV:是否使用扰动样本进行测试。

模型与数据

被评测的模型为基于MindSpore实现的OCR模型CNN-CTC,该模型主要针对场景文字识别(Scene Text Recognition)任务,用CNN模型提取特征,用CTC(Connectionist temporal classification)预测输出序列。

论文: J. Baek, G. Kim, J. Lee, S. Park, D. Han, S. Yun, S. J. Oh, and H. Lee, “What is wrong with scene text recognition model comparisons? dataset and model analysis,” ArXiv, vol. abs/1904.01906, 2019.

数据处理与模型训练参考CNN-CTC教程。评测任务需基于该教程获得预处理后的数据集和checkpoint模型文件。

预处理后的数据集为.lmdb格式,以键值对方式存储:

  • label-%09d:图片的真实标签

  • image-%09d:原始图片数据

  • num-samples:lmdb数据集中的样本数量

其中,%09d为:长度为9的数字串。形如:label-000000001。

基于自然扰动serving生成评测数据集

  1. 启动自然扰动serving服务。具体说明参考:自然扰动样本生成serving服务

    cd serving/server/
    python serving_server.py
    
  2. 基于serving服务,生成测评数据集。

    1. 在default_config.yaml中配置原来测试样本数据路径TEST_DATASET_PATH和生成扰动样本数据集路径ADV_TEST_DATASET_PATH。例如:

      TEST_DATASET_PATH: "/opt/dataset/CNNCTC_data/MJ-ST-IIIT/IIIT5k_3000"
      ADV_TEST_DATASET_PATH: "/home/mindarmour/examples/natural_robustness/ocr_evaluate/data"
      
    2. 核心代码说明:

      1. 配置扰动方法,目前可选的扰动方法及参数配置参考image transform methods。下面是一个配置例子。

        PerturbConfig = [
            {"method": "Contrast", "params": {"alpha": 1.5, "beta": 0}},
            {"method": "GaussianBlur", "params": {"ksize": 5}},
            {"method": "SaltAndPepperNoise", "params": {"factor": 0.05}},
            {"method": "Translate", "params": {"x_bias": 0.1, "y_bias": -0.1}},
            {"method": "Scale", "params": {"factor_x": 0.8, "factor_y": 0.8}},
            {"method": "Shear", "params": {"factor": 1.5, "direction": "horizontal"}},
            {"method": "Rotate", "params": {"angle": 30}},
            {"method": "MotionBlur", "params": {"degree": 5, "angle": 45}},
            {"method": "GradientBlur", "params": {"point": [50, 100], "kernel_num": 3, "center": True}},
            {"method": "GradientLuminance", "params": {"color_start": [255, 255, 255], "color_end": [0, 0, 0], "start_point": [100, 150], "scope": 0.3, "bright_rate": 0.3, "pattern": "light", "mode": "circle"}},
            {"method": "GradientLuminance", "params": {"color_start": [255, 255, 255], "color_end": [0, 0, 0], "start_point": [150, 200], "scope": 0.3, "pattern": "light", "mode": "horizontal"}},
            {"method": "GradientLuminance", "params": {"color_start": [255, 255, 255], "color_end": [0, 0, 0], "start_point": [150, 200], "scope": 0.3, "pattern": "light", "mode": "vertical"}},
            {"method": "Curve", "params": {"curves": 0.5, "depth": 3, "mode": "vertical"}},
            {"method": "Perspective", "params": {"ori_pos": [[0, 0], [0, 800], [800, 0], [800, 800]], "dst_pos": [[10, 0], [0, 800], [790, 0], [800, 800]]}},
        ]
        
      2. 准备需要扰动的数据。

        instances = []
        methods_number = 1
        outputs_number = 2
        perturb_config = json.dumps(perturb_config)
        env = lmdb.open(lmdb_paths, max_readers=32, readonly=True, lock=False, readahead=False, meminit=False)
        if not env:
            print('cannot create lmdb from %s' % (lmdb_paths))
            sys.exit(0)
        with env.begin(write=False) as txn:
            n_samples = int(txn.get('num-samples'.encode()))
            # Filtering
            filtered_labels = []
            filtered_index_list = []
            for index in range(n_samples):
                index += 1  # lmdb starts with 1
                label_key = 'label-%09d'.encode() % index
                label = txn.get(label_key).decode('utf-8')
                if len(label) > max_len: continue
                illegal_sample = False
                for char_item in label.lower():
                    if char_item not in config.CHARACTER:
                        illegal_sample = True
                        break
                if illegal_sample: continue
                filtered_labels.append(label)
                filtered_index_list.append(index)
                img_key = 'image-%09d'.encode() % index
                imgbuf = txn.get(img_key)
                instances.append({"img": imgbuf, 'perturb_config': perturb_config, "methods_number": methods_number,
                                  "outputs_number": outputs_number})
        
        print(f'num of samples in IIIT daaset: {len(filtered_index_list)}')
        
      3. 请求自然扰动serving服务,并保存serving返回的数据。

        ip = '0.0.0.0:8888'
        client = Client(ip, "perturbation", "natural_perturbation")
        start_time = time.time()
        result = client.infer(instances)
        end_time = time.time()
        print('generated natural perturbs images cost: ', end_time - start_time)
        env_save = lmdb.open(lmdb_save_path, map_size=1099511627776)
        
        txn = env.begin(write=False)
        with env_save.begin(write=True) as txn_save:
            new_index = 1
            for i, index in enumerate(filtered_index_list):
                try:
                    file_names = result[i]['file_names'].split(';')
                except:
                    print('index: ', index)
                    print(result[i])
                length = result[i]['file_length'].tolist()
                before = 0
                label = filtered_labels[i]
                label = label.encode()
                img_key = 'image-%09d'.encode() % index
                ori_img = txn.get(img_key)
                names_dict = result[i]['names_dict']
                names_dict = json.loads(names_dict)
                for name, leng in zip(file_names, length):
                    label_key = 'label-%09d'.encode() % new_index
                    txn_save.put(label_key, label)
                    img_key = 'image-%09d'.encode() % new_index
                    adv_img = result[i]['results']
                    adv_img = adv_img[before:before + leng]
                    adv_img_key = 'adv_image-%09d'.encode() % new_index
                    txn_save.put(img_key, ori_img)
                    txn_save.put(adv_img_key, adv_img)
        
                    adv_info_key = 'adv_info-%09d'.encode() % new_index
                    adv_info = json.dumps(names_dict[name]).encode()
                    txn_save.put(adv_info_key, adv_info)
                    before = before + leng
                    new_index += 1
            xn_save.put("num-samples".encode(),str(new_index - 1).encode())
        env.close()
        
    3. 执行自然扰动样本生成脚本:

      python generate_adv_samples.py
      
    4. 生成的自然扰动数据为.lmdb格式,包含下列键值对数据项:

    • label-%09d:图片的真实标签

    • image-%09d:原始图片数据

    • adv_image-%09d:生成的扰动图片数据

    • adv_info-%09d:扰动信息,包含扰动方法和参数

    • num-samples:lmdb数据集中的样本数量

CNN-CTC模型在生成扰动数据集上推理

  1. 在default_config.yaml中将测试数据集路径TEST_DATASET_PATH设置成和生成扰动样本数据集路径ADV_TEST_DATASET_PATH一样的。例如:

    TEST_DATASET_PATH:  "/home/mindarmour/examples/natural_robustness/ocr_evaluate/data"
    ADV_TEST_DATASET_PATH: "/home/mindarmour/examples/natural_robustness/ocr_evaluate/data"
    
  2. 核心脚本说明

    1. 加载模型和数据集

      ds = test_dataset_creator(is_adv=config.IS_ADV)
      net = CNNCTC(config.NUM_CLASS, config.HIDDEN_SIZE, config.FINAL_FEATURE_WIDTH)
      
      ckpt_path = config.CHECKPOINT_PATH
      param_dict = load_checkpoint(ckpt_path)
      load_param_into_net(net, param_dict)
      print('parameters loaded! from: ', ckpt_path)
      
    2. 推理并保存模型对于原始样本和扰动样本的推理结果。

      env_save = lmdb.open(lmdb_save_path, map_size=1099511627776)
      with env_save.begin(write=True) as txn_save:
          for data in ds.create_tuple_iterator():
              img, _, text, _, length = data
      
              img_tensor = Tensor(img, mstype.float32)
              model_predict = net(img_tensor)
              model_predict = np.squeeze(model_predict.asnumpy())
      
              preds_size = np.array([model_predict.shape[1]] * config.TEST_BATCH_SIZE)
              preds_index = np.argmax(model_predict, 2)
              preds_index = np.reshape(preds_index, [-1])
              preds_str = converter.decode(preds_index, preds_size)
              label_str = converter.reverse_encode(text.asnumpy(), length.asnumpy())
      
              print("Prediction samples: \n", preds_str[:5])
              print("Ground truth: \n", label_str[:5])
              for pred, label in zip(preds_str, label_str):
                  if pred == label:
                      correct_count += 1
                  count += 1
                  if config.IS_ADV:
                      pred_key = 'adv_pred-%09d'.encode() % count
                  else:
                      pred_key = 'pred-%09d'.encode() % count
      
                  txn_save.put(pred_key, pred.encode())
      accuracy = correct_count / count
      
  3. 执行eval_and_save.py脚本:

    python eval_and_save.py
    

    CNN-CTC模型在生成的自然扰动数据集上进行推理,并在ADV_TEST_DATASET_PATH中保存模型对于每个样本的推理结果。

    数据集中新增键值对数据项:

    • pred-%09d:模型对原始图片数据的预测结果

    • adv_pred-%09d:模型对扰动图片数据的预测结果

    模型对于真实样本的预测结果:

    Prediction samples:
        ['private', 'private', 'parking', 'parking', 'salutes']
    Ground truth:
        ['private', 'private', 'parking', 'parking', 'salutes']
    Prediction samples:
        ['venus', 'venus', 'its', 'its', 'the']
    Ground truth:
        ['venus', 'venus', 'its', 'its', 'the']
    Prediction samples:
        ['summer', 'summer', 'joeys', 'joeys', 'think']
    Ground truth:
        ['summer', 'summer', 'joes', 'joes', 'think']
    ...
    

    模型对于自然扰动样本的预测结果:

    Prediction samples:
        ['private', 'private', 'parking', 'parking', 'salutes']
    Ground truth:
        ['private', 'private', 'parking', 'parking', 'salutes']
    Prediction samples:
        ['dams', 'vares', 'its', 'its', 'the']
    Ground truth:
        ['venus', 'venus', 'its', 'its', 'the']
    Prediction samples:
        ['sune', 'summer', '', 'joeys', 'think']
    Ground truth:
        ['summer', 'summer', 'joes', 'joes', 'think']
    ...
    

    模型在原始测试数据集和自然扰动数据集上的准确率:

    num of samples in IIIT dataset: 5952
    Accuracy of benign sample:  0.8546195652173914
    Accuracy of perturbed sample:  0.6126019021739131
    

鲁棒性分析

根据CNN-CTC模型在扰动数据集上的表现进行统计分析。运行脚本analyse.py。

python analyse.py

分析结果:

Number of samples in analyse dataset:  5952
Accuracy of original dataset:  0.46127717391304346
Accuracy of adversarial dataset:  0.6126019021739131
Number of samples correctly predicted in original dataset but wrong in adversarial dataset:  832
Number of samples both wrong predicted in original and adversarial dataset:  1449
------------------------------------------------------------------------------
Method  Shear
Number of perturb samples: 442
Number of wrong predicted: 351
Number of correctly predicted in origin dataset but wrong in adversarial: 153
Number of both wrong predicted in origin and adversarial dataset: 198
------------------------------------------------------------------------------
Method  Contrast
Number of perturb samples: 387
Number of wrong predicted: 57
Number of correctly predicted in origin dataset but wrong in adversarial: 8
Number of both wrong predicted in origin and adversarial dataset: 49
------------------------------------------------------------------------------
Method  GaussianBlur
Number of perturb samples: 436
Number of wrong predicted: 181
Number of correctly predicted in origin dataset but wrong in adversarial: 71
Number of both wrong predicted in origin and adversarial dataset: 110
------------------------------------------------------------------------------
Method  MotionBlur
Number of perturb samples: 458
Number of wrong predicted: 215
Number of correctly predicted in origin dataset but wrong in adversarial: 92
Number of both wrong predicted in origin and adversarial dataset: 123
------------------------------------------------------------------------------
Method  GradientLuminance
Number of perturb samples: 1243
Number of wrong predicted: 154
Number of correctly predicted in origin dataset but wrong in adversarial: 4
Number of both wrong predicted in origin and adversarial dataset: 150
------------------------------------------------------------------------------
Method  Rotate
Number of perturb samples: 405
Number of wrong predicted: 298
Number of correctly predicted in origin dataset but wrong in adversarial: 136
Number of both wrong predicted in origin and adversarial dataset: 162
------------------------------------------------------------------------------
Method  SaltAndPepperNoise
Number of perturb samples: 413
Number of wrong predicted: 116
Number of correctly predicted in origin dataset but wrong in adversarial: 29
Number of both wrong predicted in origin and adversarial dataset: 87
------------------------------------------------------------------------------
Method  Translate
Number of perturb samples: 419
Number of wrong predicted: 159
Number of correctly predicted in origin dataset but wrong in adversarial: 57
Number of both wrong predicted in origin and adversarial dataset: 102
------------------------------------------------------------------------------
Method  GradientBlur
Number of perturb samples: 440
Number of wrong predicted: 92
Number of correctly predicted in origin dataset but wrong in adversarial: 26
Number of both wrong predicted in origin and adversarial dataset: 66
------------------------------------------------------------------------------
Method  Perspective
Number of perturb samples: 401
Number of wrong predicted: 181
Number of correctly predicted in origin dataset but wrong in adversarial: 75
Number of both wrong predicted in origin and adversarial dataset: 106
------------------------------------------------------------------------------
Method  Curve
Number of perturb samples: 410
Number of wrong predicted: 361
Number of correctly predicted in origin dataset but wrong in adversarial: 162
Number of both wrong predicted in origin and adversarial dataset: 199
------------------------------------------------------------------------------
Method  Scale
Number of perturb samples: 434
Number of wrong predicted: 116
Number of correctly predicted in origin dataset but wrong in adversarial: 19
Number of both wrong predicted in origin and adversarial dataset: 97
------------------------------------------------------------------------------

分析结果包含:

  1. 评测的样本数量:5888

  2. CNN-CTC模型在原数据集上的准确率:85.4%

  3. CNN-CTC模型在扰动数据集上的准确率:57.2%

  4. 在原图上预测正确,扰动后图片预测错误的 样本数量:1736

  5. 在原图和扰动后图片上均预测错误的样本数量:782

  6. 对于每一个扰动方法,包含样本数量、扰动样本预测错误的数量、原样本预测正确扰动后预测错误的数量、原样本和扰动样本均预测错误的数量。

如果模型对某扰动方法扰动后的图片预测错误率较高,则说明CNN-CTC模型对于该方法鲁棒性较差,建议针对性提升,如Rotate、Curve、MotionBlur和Shear这几种扰动方法,大部分扰动后的图片都预测错误,建议进一步分析。

同时在ADV_TEST_DATASET_PATH路径下生成3个文件夹:

adv_wrong_pred                  # 模型对于扰动后图片分类错误的数据集
ori_corret_adv_wrong_pred       # 模型对于原图分类正确但扰动后图片分类错误的数据集
ori_wrong_adv_wrong_pred        # 模型对于原图分类和扰动后图片均分类错误的数据集

每个文件夹均按照扰动方法分类:

1646730529400

每张图片的命名格式:真值-预测值.png,如下图:

1646812837049

存储的图片可供进一步分析,是模型质量问题、图片质量问题、还是扰动方法影响图片语义从而导致预测错误。

1646812837049