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【Tool】Tensorflow移动端模型转换

【Tool】Tensorflow移动端模型转换

作者: ItchyHiker | 来源:发表于2018-08-30 16:43 被阅读0次

    Tags: Tool DeepLearning


    Screen Shot 2018-09-17 at 2.31.54 PM.png
    深度学习和机器学习的移动端化是未来的趋势,这两年各个大厂也在这方面发力,竞相推出自己移动端的推理框架。Google有Tensorflow Lite, Apple有CoreML,Facebook有Caffe2, Tencent的NCNN最近也是风头正盛,百度有Paddle Mobile, 小米有MACE... 总之各个平台之间不仅性能有差异,光是要把训练好的模型正确的转换过去,就得吐一口血。
    扯远了,这篇文章主要记录自己在使用Tensorflow+Keras训练模型,同时将模型转换到移动端的一些经验,会持续更新, 现有的移动端框架主要是Tensorflow Lite和CoreML,未来考虑加入Caffe2和NCNN。

    Tensorflow 转 Tensorflow Lite

    在Android端Tensorflow Lite 会使用 Android Neural Networks API进行加速,但是需要Android 8.1以上才支持:


    Screen Shot 2018-09-17 at 2.39.49 PM.png

    Tensorflow提供官方转换工具toco可以直接将tensorflow .pb模型转换为.tflite模型。

    Screen Shot 2018-09-17 at 3.33.43 PM.png

    toco

    usage: toco [-h] --output_file OUTPUT_FILE
                (--graph_def_file GRAPH_DEF_FILE | --saved_model_dir SAVED_MODEL_DIR | --keras_model_file KERAS_MODEL_FILE)
                [--output_format {TFLITE,GRAPHVIZ_DOT}]
                [--inference_type {FLOAT,QUANTIZED_UINT8}]
                [--inference_input_type {FLOAT,QUANTIZED_UINT8}]
                [--input_arrays INPUT_ARRAYS] [--input_shapes INPUT_SHAPES]
                [--output_arrays OUTPUT_ARRAYS]
                [--saved_model_tag_set SAVED_MODEL_TAG_SET]
                [--saved_model_signature_key SAVED_MODEL_SIGNATURE_KEY]
                [--std_dev_values STD_DEV_VALUES] [--mean_values MEAN_VALUES]
                [--default_ranges_min DEFAULT_RANGES_MIN]
                [--default_ranges_max DEFAULT_RANGES_MAX]
                [--quantize_weights QUANTIZE_WEIGHTS] [--drop_control_dependency]
                [--reorder_across_fake_quant] [--change_concat_input_ranges]
                [--allow_custom_ops] [--dump_graphviz_dir DUMP_GRAPHVIZ_DIR]
                [--dump_graphviz_video]
    
    
    • output_file: 输出模型.tflite后缀
    • graph_def_file: 静态图文件, saved_model_dir: 模型保存路径, keras_model_file: keras模型文件, 三者必须有且只能有一个
    • output_format: 输出文件类型
    • inference_type: 这个参数可以用来对模型进行量化,从而达到不同的accuracy/speed的平衡
    • inference_input_type: 输入类型,在使用QUANTIZED_UINT8的时候也需要配置 --std_dev_values --mean_values, --default_ranges_min --default_ranges_max这些参数
      我自己试验了下使用inference_type和inference_input_type使用QUANTIZED_UINT8比float要快很多(有时间给一个例子)
    • input_shape: 输出图片的大小
    • input_array: 图输入节点
    • output_array: 图输出节点
    • allow_custom_ops: 定义了官方不支持的layer或者op的时候需要开启
      其他参数可以在用到的时候在官网参考。
      从toco的使用提示可以看到,我们需要提供的参数有,静态图.pb文件,生成.tflite文件,输出的格式,输入的节点shape, 输入的节点名称,输出节点名称。
      成功实例参考:
    toco --graph_def_file=DeeplabV3++_portrait_384_1_05alpha.pb --output_file=DeeplabV3++_portrait_384_1_05alpha.tflite --output_format=TFLITE --input_shape=1,384,384,3 --input_array=input_1 --output_array=output_0 --inference_type=float --allow_custom_ops
    

    下面介绍下如何查看tensorflow模型中节点名称

    • 如何查看checkpoints中节点名称
    saver = tf.train.import_meta_graph(/path/to/meta/graph)
    sess = tf.Session()
    saver.restore(sess, /path/to/checkpoints)
    graph = sess.graph
    print([node.name for node in graph.as_graph_def().node])
    
    • 如何查看静态图.pb节点信息:
      以我自己的simplenet 静态图文件为例:
    """FIND GRAPH INFO"""
    tf_model_path = "./simplenet_V2_8M.pb"
    with open(tf_model_path , 'rb') as f:
        serialized = f.read()
    tf.reset_default_graph()
    original_gdef = tf.GraphDef()
    original_gdef.ParseFromString(serialized)
    
    with tf.Graph().as_default() as g:
        tf.import_graph_def(original_gdef, name ='')
        ops = g.get_operations()
        N = len(ops)
        for i in [0,1,2,N-3,N-2,N-1]: # for循环设置输出的节点信息
            print('\n\nop id {} : op type: "{}"'.format(str(i), ops[i].type))
            print('input(s):')
            for x in ops[i].inputs:
                print("name = {}, shape: {}, ".format(x.name, x.get_shape()))
            print('\noutput(s):'),
            for x in ops[i].outputs:
                print("name = {}, shape: {},".format(x.name, x.get_shape()))
    

    输出如下:

    op id 0 : op type: "Placeholder"
    input(s):
    
    output(s):
    name = input_1:0, shape: (?, 32, 32, 3),
    
    
    op id 1 : op type: "Const"
    input(s):
    
    output(s):
    name = block1_conv/kernel:0, shape: (3, 3, 3, 128),
    
    
    op id 2 : op type: "Identity"
    input(s):
    name = block1_conv/kernel:0, shape: (3, 3, 3, 128), 
    
    output(s):
    name = block1_conv/kernel/read:0, shape: (3, 3, 3, 128),
    
    
    op id 190 : op type: "MatMul"
    input(s):
    name = global_average_pooling2d_1/Mean:0, shape: (?, 600), 
    name = dense_1/kernel/read:0, shape: (600, 10), 
    
    output(s):
    name = dense_1/MatMul:0, shape: (?, 10),
    
    
    op id 191 : op type: "BiasAdd"
    input(s):
    name = dense_1/MatMul:0, shape: (?, 10), 
    name = dense_1/bias/read:0, shape: (10,), 
    
    output(s):
    name = dense_1/BiasAdd:0, shape: (?, 10),
    
    
    op id 192 : op type: "Softmax"
    input(s):
    name = dense_1/BiasAdd:0, shape: (?, 10), 
    
    output(s):
    name = activation_1/Softmax:0, shape: (?, 10),
    

    得到这些信息之后我就可以给toco提供合适的信息进行转换:

    toco --graph_def_file=simplenet_V2_8M.pb --output_file=simplenet_v2_8M.tflite --output_format=TFLITE --input_shape=1,32,32,3 --input_arrays=input_1 --output_arrays=activation_1/Softmax
    

    转换成功之后会生成.tflite文件,就可以用于移动端部署了。


    tflite

    实际上在直接用于移动端部署之前,你可能需要测试下你的tflite模型的准确度,这就需要直接在Python里面调用tflite:

    import numpy as np
    import tensorflow as tf
    
    # Load TFLite model and allocate tensors.
    interpreter = tf.contrib.lite.Interpreter(model_path="converted_model.tflite")
    interpreter.allocate_tensors()
    
    # Get input and output tensors.
    input_details = interpreter.get_input_details()
    output_details = interpreter.get_output_details()
    
    # Test model on random input data.
    input_shape = input_details[0]['shape']
    # change the following line to feed into your own data.
    input_data = np.array(np.random.random_sample(input_shape), dtype=np.float32)
    interpreter.set_tensor(input_details[0]['index'], input_data)
    
    interpreter.invoke()
    output_data = interpreter.get_tensor(output_details[0]['index'])
    print(output_data)
    

    参考资料: https://stackoverflow.com/questions/50764572/how-can-i-test-a-tflite-model-to-prove-that-it-behaves-as-the-original-model-us

    Tensorlfow 转 CoreML

    TF-COREML

    CoreML并不提供将tensorflow模型直接转换为mlmodel的工具,但是有keras接口。此外有第三方转换工具tf-coreml可以用来转换,这里看下如何使用这个工具转换。

    首先将我们保存的checkpoints保存为静态图,.pb格式。

    然后要输入的参数有:

    • tf_model_path: .pb静态图模型路径
    • mlmodel_path: 生成的CoreML模型路径地址
    • input_name_shape_dict: 网络的输入名称和数据的大小(要根据原始的模型输入确定)
    • output_feature_names: 网络输出的名称(要根据原始的模型输出确定)

    此外也可以对输入的数据做一些归一化处理:

    • image_scale:
    • red_bias
    • green_bias
    • blue_bias
    import tensorflow as tf
    import tfcoreml
    from coremltools.proto import FeatureTypes_pb2 as _FeatureTypes_pb2
    import coremltools
    
    """ FIND GRAPH INFO """
    tf_model_path = "/tmp//retrained_graph.pb"
    with open(tf_model_path , 'rb') as f:
        serialized = f.read()
    tf.reset_default_graph()
    original_gdef = tf.GraphDef()
    original_gdef.ParseFromString(serialized)
    
    with tf.Graph().as_default() as g:
        tf.import_graph_def(original_gdef, name ='')
        ops = g.get_operations()
        N = len(ops)
        for i in [0,1,2,N-3,N-2,N-1]:
            print('\n\nop id {} : op type: "{}"'.format(str(i), ops[i].type))
            print('input(s):')
            for x in ops[i].inputs:
                print("name = {}, shape: {}, ".format(x.name, x.get_shape()))
            print('\noutput(s):'),
            for x in ops[i].outputs:
                print("name = {}, shape: {},".format(x.name, x.get_shape()))
    
    """ CONVERT TF TO CORE ML """
    # Model Shape
    input_tensor_shapes = {"input:0":[1,224,224,3]} 
    # Input Name
    image_input_name = ['input:0']
    # Output CoreML model path
    coreml_model_file = '/tmp/myModel.mlmodel'
    # Output name
    output_tensor_names = ['final_result:0']
    # Label file for classification
    class_labels = '/tmp/retrained_labels.txt'
    
    #Convert Process
    coreml_model = tfcoreml.convert(
            tf_model_path=tf_model_path,
            mlmodel_path=coreml_model_file,
            input_name_shape_dict=input_tensor_shapes,
            output_feature_names=output_tensor_names,
            image_input_names = image_input_name,
            class_labels = class_labels)
    
    # Get image pre-processing parameters of a saved CoreML model
    spec = coremltools.models.utils.load_spec(coreml_model_file)
    if spec.WhichOneof('Type') == 'neuralNetworkClassifier':
      nn = spec.neuralNetworkClassifier
      print("neuralNetworkClassifier")
    if spec.WhichOneof('Type') == 'neuralNetwork':
      nn = spec.neuralNetwork  
      print("neuralNetwork")
    if spec.WhichOneof('Type') == 'neuralNetworkRegressor':
      nn = spec.neuralNetworkRegressor
      print("neuralNetworkClassifierRegressor")
    
    preprocessing = nn.preprocessing[0].scaler
    print('channel scale: ', preprocessing.channelScale)
    print('blue bias: ', preprocessing.blueBias)
    print('green bias: ', preprocessing.greenBias)
    print('red bias: ', preprocessing.redBias)
    
    inp = spec.description.input[0]
    if inp.type.WhichOneof('Type') == 'imageType':
      colorspace = _FeatureTypes_pb2.ImageFeatureType.ColorSpace.Name(inp.type.imageType.colorSpace)
      print('colorspace: ', colorspace)
    
    coreml_model = tfcoreml.convert(
            tf_model_path=tf_model_path,
            mlmodel_path=coreml_model_file,
            input_name_shape_dict=input_tensor_shapes,
            output_feature_names=output_tensor_names,
            image_input_names = image_input_name,
            class_labels = class_labels,
            red_bias = -1,
            green_bias = -1,
            blue_bias = -1,
            image_scale = 2.0/255.0)
    

    COREMLTOOLS

    下面介绍下苹果官方的转换工具。现在已经发布2.0版本了。支持很多平台:


    Screen Shot 2018-09-18 at 10.26.47 AM.png

    模型量化:


    Screen Shot 2018-09-18 at 10.17.13 AM.png
    提供一个Keras 模型转换 coreml模型脚本:
      import coremltools
      import keras
      from keras.models import load_model
      from keras.utils.generic_utils import CustomObjectScope
      class_labels = []
      for i in range(62):
           class_labels.append(str(i))
    
       with CustomObjectScope({'relu6': keras.applications.mobilenet.relu6}):
          keras_model = load_model('traffic_sign_with_class_weights.h5')
          coreml_model = coremltools.converters.keras.convert(keras_model,
                                                          input_names=['input_1'],
                                                          image_input_names='input_1',
                                                          output_names='activation_1',
                                                          image_scale=2/255.0,
                                                          red_bias=-1,
                                                          green_bias=-1,
                                                          blue_bias=-1,
                                                          class_labels=class_labels)
      
     coreml_model.save('traffic_sign_with_class_weights.mlmodel')
    

    我自己实现的一个人像分割模型,然后使用keras间接移植到IOS设备上,可以实时进行检测,效果还不错哈。


    head_segmentation.jpg

    如果有想了解深度学习模型移动端移植问题的可以咨询我的微信: ItchHacker。欢迎推荐江浙和上海地区的计算机视觉,数字图像处理岗位。

    Reference

    1. https://qiita.com/hengsokvisal/items/dbb61851a8c76c96c700
    2. https://www.appcoda.com/coreml2/
    3. https://www.appcoda.com/coreml-introduction/
    4. https://www.raywenderlich.com/577-core-ml-and-vision-machine-learning-in-ios-11-tutorial
    5. https://sourcediving.com/machine-learning-on-mobile-fc34be69df1a
      6.https://github.com/tensorflow/tensorflow/tree/master/tensorflow/contrib/lite/toco
    6. https://blog.csdn.net/u011511601/article/details/80262707
    7. https://blog.algorithmia.com/machine-learning-and-mobile-deploying-models-on-the-edge/
    8. https://github.com/tensorflow/tensorflow/issues/15122

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