Merge pull request #58 from guoshengCS/add_caffe2paddle_tool

add tools for model conversion from Caffe to PaddlePaddle

image_classification/caffe2paddle/README.md

+## 使用说明
+
+`caffe2paddle.py`提供了将Caffe训练的模型转换为PaddlePaddle可使用的模型的接口`ModelConverter`，其封装了图像领域常用的Convolution、BatchNorm等layer的转换函数，可以完成VGG、ResNet等常用模型的转换。模型转换的基本过程是：基于Caffe的Python API加载模型并依次获取每一个layer的信息，将其中的参数根据layer类型与PaddlePaddle适配后序列化保存（对于Pooling等无需训练的layer不做处理），输出可以直接为PaddlePaddle的Python API加载使用的模型文件。
+
+可以按如下方法使用`ModelConverter`接口：
+
+```python
+# 定义以下变量为相应的文件路径和文件名
+caffe_model_file = "./ResNet-50-deploy.prototxt"        # Caffe网络配置文件的路径
+caffe_pretrained_file = "./ResNet-50-model.caffemodel"  # Caffe模型文件的路径
+paddle_tar_name = "Paddle_ResNet50.tar.gz"              # 输出的Paddle模型的文件名
+
+# 初始化，从指定文件加载模型
+converter = ModelConverter(caffe_model_file=caffe_model_file,
+                           caffe_pretrained_file=caffe_pretrained_file,
+                           paddle_tar_name=paddle_tar_name)
+# 进行模型转换
+converter.convert()
+```
+
+`caffe2paddle.py`中已提供以上步骤，修改其中文件相关变量的值后执行`python caffe2paddle.py`即可完成模型转换。此外，为辅助验证转换结果，`ModelConverter`中封装了使用Caffe API预测的接口`caffe_predict`，使用如下所示，将会打印按类别概率排序的(类别id, 概率)的列表:
+
+```python
+# img为图片路径，mean_file为图像均值文件的路径
+converter.caffe_predict(img="./cat.jpg", mean_file="./imagenet/ilsvrc_2012_mean.npy")
+```
+
+需要注意，在模型转换时会对layer的参数进行命名，这里默认使用PaddlePaddle中默认的layer和参数命名规则：以`wrap_name_default`中的值和该layer类型的调用计数构造layer name，并以此为前缀构造参数名，比如第一个InnerProduct层（相应转换函数说明见下方）的bias参数将被命名为`___fc_layer_0__.wbias`。
+
+```python
+# 对InnerProduct层的参数进行转换，使用name值构造对应layer的参数名
+# wrap_name_default设置默认name值为fc_layer
+@wrap_name_default("fc_layer")
+def convert_InnerProduct_layer(self, params, name=None)
+```
+
+为此，在验证和使用转换得到的模型时，编写PaddlePaddle网络配置无需指定layer name并且要保证和Caffe端模型使用同样的拓扑顺序，尤其是对于ResNet这种有分支的网络结构，要保证两分支在PaddlePaddle和Caffe中先后顺序一致，这样才能够使得模型参数正确加载。
+
+如果不希望使用默认的命名，并且在PaddlePaddle网络配置中指定了layer name，可以建立Caffe和PaddlePaddle网络配置间layer name对应关系的`dict`并在调用`ModelConverter.convert`时作为`name_map`的值传入，这样在命名保存layer中的参数时将使用相应的layer name，不受拓扑顺序的影响。另外这里只针对Caffe网络配置中Convolution、InnerProduct和BatchNorm类别的layer建立`name_map`即可（一方面，对于Pooling等无需训练的layer不需要保存，故这里没有提供转换接口；另一方面，对于Caffe中的Scale类别的layer，由于Caffe和PaddlePaddle在实现上的一些差别，PaddlePaddle中的batch_norm层是BatchNorm和Scale层的复合，故这里对Scale进行了特殊处理）。

image_classification/caffe2paddle/caffe2paddle.py

+import os
+import struct
+import gzip
+import tarfile
+import cStringIO
+import numpy as np
+import cv2
+import caffe
+from paddle.proto.ParameterConfig_pb2 import ParameterConfig
+from paddle.trainer_config_helpers.default_decorators import wrap_name_default
+
+
+class ModelConverter(object):
+    def __init__(self, caffe_model_file, caffe_pretrained_file,
+                 paddle_tar_name):
+        self.net = caffe.Net(caffe_model_file, caffe_pretrained_file,
+                             caffe.TEST)
+        self.tar_name = paddle_tar_name
+        self.params = dict()
+        self.pre_layer_name = ""
+        self.pre_layer_type = ""
+
+    def convert(self, name_map=None):
+        layer_dict = self.net.layer_dict
+        for layer_name in layer_dict.keys():
+            layer = layer_dict[layer_name]
+            layer_params = layer.blobs
+            layer_type = layer.type
+            if len(layer_params) > 0:
+                self.pre_layer_name = getattr(
+                    self, "convert_" + layer_type + "_layer")(
+                        layer_params,
+                        name=None
+                        if name_map == None else name_map.get(layer_name))
+            self.pre_layer_type = layer_type
+        with gzip.open(self.tar_name, 'w') as f:
+            self.to_tar(f)
+        return
+
+    def to_tar(self, f):
+        tar = tarfile.TarFile(fileobj=f, mode='w')
+        for param_name in self.params.keys():
+            param_conf, param_data = self.params[param_name]
+
+            confStr = param_conf.SerializeToString()
+            tarinfo = tarfile.TarInfo(name="%s.protobuf" % param_name)
+            tarinfo.size = len(confStr)
+            buf = cStringIO.StringIO(confStr)
+            buf.seek(0)
+            tar.addfile(tarinfo, fileobj=buf)
+
+            buf = cStringIO.StringIO()
+            self.serialize(param_data, buf)
+            tarinfo = tarfile.TarInfo(name=param_name)
+            buf.seek(0)
+            tarinfo.size = len(buf.getvalue())
+            tar.addfile(tarinfo, buf)
+
+    @staticmethod
+    def serialize(data, f):
+        f.write(struct.pack("IIQ", 0, 4, data.size))
+        f.write(data.tobytes())
+
+    @wrap_name_default("conv")
+    def convert_Convolution_layer(self, params, name=None):
+        for i in range(len(params)):
+            data = np.array(params[i].data)
+            if len(params) == 2:
+                suffix = "0" if i == 0 else "bias"
+                file_name = "_%s.w%s" % (name, suffix)
+            else:
+                file_name = "_%s.w%s" % (name, str(i))
+            param_conf = ParameterConfig()
+            param_conf.name = file_name
+            param_conf.size = reduce(lambda a, b: a * b, data.shape)
+            self.params[file_name] = (param_conf, data.flatten())
+
+        return name
+
+    @wrap_name_default("fc_layer")
+    def convert_InnerProduct_layer(self, params, name=None):
+        for i in range(len(params)):
+            data = np.array(params[i].data)
+            if len(params) == 2:
+                suffix = "0" if i == 0 else "bias"
+                file_name = "_%s.w%s" % (name, suffix)
+            else:
+                file_name = "_%s.w%s" % (name, str(i))
+            data = np.transpose(data)
+            param_conf = ParameterConfig()
+            param_conf.name = file_name
+            dims = list(data.shape)
+            if len(dims) < 2:
+                dims.insert(0, 1)
+            param_conf.size = reduce(lambda a, b: a * b, dims)
+            param_conf.dims.extend(dims)
+            self.params[file_name] = (param_conf, data.flatten())
+        return name
+
+    @wrap_name_default("batch_norm")
+    def convert_BatchNorm_layer(self, params, name=None):
+        scale = 1 / np.array(params[-1].data)[0] if np.array(
+            params[-1].data)[0] != 0 else 0
+        for i in range(2):
+            data = np.array(params[i].data) * scale
+            file_name = "_%s.w%s" % (name, str(i + 1))
+            param_conf = ParameterConfig()
+            param_conf.name = file_name
+            dims = list(data.shape)
+            assert len(dims) == 1
+            dims.insert(0, 1)
+            param_conf.size = reduce(lambda a, b: a * b, dims)
+            param_conf.dims.extend(dims)
+            self.params[file_name] = (param_conf, data.flatten())
+        return name
+
+    def convert_Scale_layer(self, params, name=None):
+        assert self.pre_layer_type == "BatchNorm"
+        name = self.pre_layer_name
+        for i in range(len(params)):
+            data = np.array(params[i].data)
+            suffix = "0" if i == 0 else "bias"
+            file_name = "_%s.w%s" % (name, suffix)
+            param_conf = ParameterConfig()
+            param_conf.name = file_name
+            dims = list(data.shape)
+            assert len(dims) == 1
+            dims.insert(0, 1)
+            param_conf.size = reduce(lambda a, b: a * b, dims)
+            if i == 1:
+                param_conf.dims.extend(dims)
+            self.params[file_name] = (param_conf, data.flatten())
+        return name
+
+    def caffe_predict(self,
+                      img,
+                      mean_file='./caffe/imagenet/ilsvrc_2012_mean.npy'):
+        net = self.net
+
+        net.blobs['data'].data[...] = load_image(img, mean_file=mean_file)
+        out = net.forward()
+
+        output_prob = net.blobs['prob'].data[0].flatten()
+        print zip(np.argsort(output_prob)[::-1], np.sort(output_prob)[::-1])
+
+
+def load_image(file, resize_size=256, crop_size=224, mean_file=None):
+    # load image
+    im = cv2.imread(file)
+    # resize
+    h, w = im.shape[:2]
+    h_new, w_new = resize_size, resize_size
+    if h > w:
+        h_new = resize_size * h / w
+    else:
+        w_new = resize_size * w / h
+    im = cv2.resize(im, (h_new, w_new), interpolation=cv2.INTER_CUBIC)
+    # crop
+    h, w = im.shape[:2]
+    h_start = (h - crop_size) / 2
+    w_start = (w - crop_size) / 2
+    h_end, w_end = h_start + crop_size, w_start + crop_size
+    im = im[h_start:h_end, w_start:w_end, :]
+    # transpose to CHW order
+    im = im.transpose((2, 0, 1))
+
+    if mean_file:
+        mu = np.load(mean_file)
+        mu = mu.mean(1).mean(1)
+        im = im - mu[:, None, None]
+    im = im / 255.0
+    return im
+
+
+if __name__ == "__main__":
+    caffe_model_file = "./ResNet-50-deploy.prototxt"
+    caffe_pretrained_file = "./ResNet-50-model.caffemodel"
+    paddle_tar_name = "Paddle_ResNet50.tar.gz"
+
+    converter = ModelConverter(
+        caffe_model_file=caffe_model_file,
+        caffe_pretrained_file=caffe_pretrained_file,
+        paddle_tar_name=paddle_tar_name)
+    converter.convert()
+
+    converter.caffe_predict("./cat.jpg",
+                            "./caffe/imagenet/ilsvrc_2012_mean.npy")