export Keras model to .pb file and optimize for in

I am developing an android application for the purpose of age and gender recognition. I have found a useful model in GitHub. They are building a Keras model (tensorflow backend) based on a first-place winning paper. They have provided python modules to train and build the network, already trained weights file to download and work with, and a working demo on web cam.

I want to convert their model, in the demo, with the provided weights to .pb file so that it is executable on android as well.

I used this code to convert with minor model-dependent modifications:

from keras.models import Sequential
from keras.models import model_from_json
from keras import backend as K
import tensorflow as tf
from tensorflow.python.tools import freeze_graph
import os

# Load existing model.
with open("model.json",'r') as f:
    modelJSON = f.read()

model = model_from_json(modelJSON)
model.load_weights("weights.18-4.06.hdf5")
print(model.summary())

# All new operations will be in test mode from now on.
K.set_learning_phase(0)

# Serialize the model and get its weights, for quick re-building.
config = model.get_config()
weights = model.get_weights()

# Re-build a model where the learning phase is now hard-coded to 0.
#new_model = model.from_config(config)
#new_model.set_weights(weights)

temp_dir = "graph"
checkpoint_prefix = os.path.join(temp_dir, "saved_checkpoint")
checkpoint_state_name = "checkpoint_state"
input_graph_name = "input_graph.pb"
output_graph_name = "output_graph.pb"

# Temporary save graph to disk without weights included.
saver = tf.train.Saver()
checkpoint_path = saver.save(K.get_session(), checkpoint_prefix, global_step=0, latest_filename=checkpoint_state_name)
tf.train.write_graph(K.get_session().graph, temp_dir, input_graph_name)

input_graph_path = os.path.join(temp_dir, input_graph_name)
input_saver_def_path = ""
input_binary = False
output_node_names = "dense_1/Softmax,dense_2/Softmax" # model dependent
restore_op_name = "save/restore_all"
filename_tensor_name = "save/Const:0"
output_graph_path = os.path.join(temp_dir, output_graph_name)
clear_devices = False

# Embed weights inside the graph and save to disk.
freeze_graph.freeze_graph(input_graph_path, input_saver_def_path,
                          input_binary, checkpoint_path,
                          output_node_names, restore_op_name,
                          filename_tensor_name, output_graph_path,
                          clear_devices, "")

I produced the model.json file fro the demo directly. The code of the main function of demo.py file with the model.json is:

def main():
    args = get_args()
    depth = args.depth
    k = args.width
    weight_file = args.weight_file

    if not weight_file:
        weight_file = get_file("weights.18-4.06.hdf5", pretrained_model, cache_subdir="pretrained_models",
                               file_hash=modhash, cache_dir=os.path.dirname(os.path.abspath(__file__)))

    # for face detection
    detector = dlib.get_frontal_face_detector()

    # load model and weights
    img_size = 64
    model = WideResNet(img_size, depth=depth, k=k)()
    model.load_weights(weight_file)
    print(model.summary())

    # write model to json
    model_json = model.to_json()
    with open("model.json", "w") as json_file:
        json_file.write(model_json)

    for img in yield_images():
        input_img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
        img_h, img_w, _ = np.shape(input_img)

        # detect faces using dlib detector
        detected = detector(input_img, 1)
        faces = np.empty((len(detected), img_size, img_size, 3))

        if len(detected) > 0:
            for i, d in enumerate(detected):
                x1, y1, x2, y2, w, h = d.left(), d.top(), d.right() + 1, d.bottom() + 1, d.width(), d.height()
                xw1 = max(int(x1 - 0.4 * w), 0)
                yw1 = max(int(y1 - 0.4 * h), 0)
                xw2 = min(int(x2 + 0.4 * w), img_w - 1)
                yw2 = min(int(y2 + 0.4 * h), img_h - 1)
                cv2.rectangle(img, (x1, y1), (x2, y2), (255, 0, 0), 2)
                # cv2.rectangle(img, (xw1, yw1), (xw2, yw2), (255, 0, 0), 2)
                faces[i, :, :, :] = cv2.resize(img[yw1:yw2 + 1, xw1:xw2 + 1, :], (img_size, img_size))

            # predict ages and genders of the detected faces
            results = model.predict(faces)
            predicted_genders = results[0]
            ages = np.arange(0, 101).reshape(101, 1)
            predicted_ages = results[1].dot(ages).flatten()

            # draw results
            for i, d in enumerate(detected):
                label = "{}, {}".format(int(predicted_ages[i]),
                                        "F" if predicted_genders[i][0] > 0.5 else "M")
                draw_label(img, (d.left(), d.top()), label)

        cv2.imshow("result", img)
        key = cv2.waitKey(30)

        if key == 27:
            break


if __name__ == '__main__':
    main()

The code successfully compiles and produces multiple checkpoint files along side with a .pb file.

This is the graph summary of the model:

__________________________________________________________________________________________________
Layer (type)                    Output Shape         Param #     Connected to                     
==================================================================================================
input_1 (InputLayer)            (None, 64, 64, 3)    0                                            
__________________________________________________________________________________________________
conv2d_1 (Conv2D)               (None, 64, 64, 16)   432         input_1[0][0]                    
__________________________________________________________________________________________________
batch_normalization_1 (BatchNor (None, 64, 64, 16)   64          conv2d_1[0][0]                   
__________________________________________________________________________________________________
activation_1 (Activation)       (None, 64, 64, 16)   0           batch_normalization_1[0][0]      
__________________________________________________________________________________________________
conv2d_2 (Conv2D)               (None, 64, 64, 128)  18432       activation_1[0][0]               
__________________________________________________________________________________________________
batch_normalization_2 (BatchNor (None, 64, 64, 128)  512         conv2d_2[0][0]                   
__________________________________________________________________________________________________
activation_2 (Activation)       (None, 64, 64, 128)  0           batch_normalization_2[0][0]      
__________________________________________________________________________________________________
conv2d_3 (Conv2D)               (None, 64, 64, 128)  147456      activation_2[0][0]               
__________________________________________________________________________________________________
conv2d_4 (Conv2D)               (None, 64, 64, 128)  2048        activation_1[0][0]               
__________________________________________________________________________________________________
add_1 (Add)                     (None, 64, 64, 128)  0           conv2d_3[0][0]                   
                                                                 conv2d_4[0][0]                   
__________________________________________________________________________________________________
batch_normalization_3 (BatchNor (None, 64, 64, 128)  512         add_1[0][0]                      
__________________________________________________________________________________________________
activation_3 (Activation)       (None, 64, 64, 128)  0           batch_normalization_3[0][0]      
__________________________________________________________________________________________________
conv2d_5 (Conv2D)               (None, 64, 64, 128)  147456      activation_3[0][0]               
__________________________________________________________________________________________________
batch_normalization_4 (BatchNor (None, 64, 64, 128)  512         conv2d_5[0][0]                   
__________________________________________________________________________________________________
activation_4 (Activation)       (None, 64, 64, 128)  0           batch_normalization_4[0][0]      
__________________________________________________________________________________________________
conv2d_6 (Conv2D)               (None, 64, 64, 128)  147456      activation_4[0][0]               
__________________________________________________________________________________________________
add_2 (Add)                     (None, 64, 64, 128)  0           conv2d_6[0][0]                   
                                                                 add_1[0][0]                      
__________________________________________________________________________________________________
batch_normalization_5 (BatchNor (None, 64, 64, 128)  512         add_2[0][0]                      
__________________________________________________________________________________________________
activation_5 (Activation)       (None, 64, 64, 128)  0           batch_normalization_5[0][0]      
__________________________________________________________________________________________________
conv2d_7 (Conv2D)               (None, 32, 32, 256)  294912      activation_5[0][0]               
__________________________________________________________________________________________________
batch_normalization_6 (BatchNor (None, 32, 32, 256)  1024        conv2d_7[0][0]                   
__________________________________________________________________________________________________
activation_6 (Activation)       (None, 32, 32, 256)  0           batch_normalization_6[0][0]      
__________________________________________________________________________________________________
conv2d_8 (Conv2D)               (None, 32, 32, 256)  589824      activation_6[0][0]               
__________________________________________________________________________________________________
conv2d_9 (Conv2D)               (None, 32, 32, 256)  32768       activation_5[0][0]               
__________________________________________________________________________________________________
add_3 (Add)                     (None, 32, 32, 256)  0           conv2d_8[0][0]                   
                                                                 conv2d_9[0][0]                   
__________________________________________________________________________________________________
batch_normalization_7 (BatchNor (None, 32, 32, 256)  1024        add_3[0][0]                      
__________________________________________________________________________________________________
activation_7 (Activation)       (None, 32, 32, 256)  0           batch_normalization_7[0][0]      
__________________________________________________________________________________________________
conv2d_10 (Conv2D)              (None, 32, 32, 256)  589824      activation_7[0][0]               
__________________________________________________________________________________________________
batch_normalization_8 (BatchNor (None, 32, 32, 256)  1024        conv2d_10[0][0]                  
__________________________________________________________________________________________________
activation_8 (Activation)       (None, 32, 32, 256)  0           batch_normalization_8[0][0]      
__________________________________________________________________________________________________
conv2d_11 (Conv2D)              (None, 32, 32, 256)  589824      activation_8[0][0]               
__________________________________________________________________________________________________
add_4 (Add)                     (None, 32, 32, 256)  0           conv2d_11[0][0]                  
                                                                 add_3[0][0]                      
__________________________________________________________________________________________________
batch_normalization_9 (BatchNor (None, 32, 32, 256)  1024        add_4[0][0]                      
__________________________________________________________________________________________________
activation_9 (Activation)       (None, 32, 32, 256)  0           batch_normalization_9[0][0]      
__________________________________________________________________________________________________
conv2d_12 (Conv2D)              (None, 16, 16, 512)  1179648     activation_9[0][0]               
__________________________________________________________________________________________________
batch_normalization_10 (BatchNo (None, 16, 16, 512)  2048        conv2d_12[0][0]                  
__________________________________________________________________________________________________
activation_10 (Activation)      (None, 16, 16, 512)  0           batch_normalization_10[0][0]     
__________________________________________________________________________________________________
conv2d_13 (Conv2D)              (None, 16, 16, 512)  2359296     activation_10[0][0]              
__________________________________________________________________________________________________
conv2d_14 (Conv2D)              (None, 16, 16, 512)  131072      activation_9[0][0]               
__________________________________________________________________________________________________
add_5 (Add)                     (None, 16, 16, 512)  0           conv2d_13[0][0]                  
                                                                 conv2d_14[0][0]                  
__________________________________________________________________________________________________
batch_normalization_11 (BatchNo (None, 16, 16, 512)  2048        add_5[0][0]                      
__________________________________________________________________________________________________
activation_11 (Activation)      (None, 16, 16, 512)  0           batch_normalization_11[0][0]     
__________________________________________________________________________________________________
conv2d_15 (Conv2D)              (None, 16, 16, 512)  2359296     activation_11[0][0]              
__________________________________________________________________________________________________
batch_normalization_12 (BatchNo (None, 16, 16, 512)  2048        conv2d_15[0][0]                  
__________________________________________________________________________________________________
activation_12 (Activation)      (None, 16, 16, 512)  0           batch_normalization_12[0][0]     
__________________________________________________________________________________________________
conv2d_16 (Conv2D)              (None, 16, 16, 512)  2359296     activation_12[0][0]              
__________________________________________________________________________________________________
add_6 (Add)                     (None, 16, 16, 512)  0           conv2d_16[0][0]                  
                                                                 add_5[0][0]                      
__________________________________________________________________________________________________
batch_normalization_13 (BatchNo (None, 16, 16, 512)  2048        add_6[0][0]                      
__________________________________________________________________________________________________
activation_13 (Activation)      (None, 16, 16, 512)  0           batch_normalization_13[0][0]     
__________________________________________________________________________________________________
average_pooling2d_1 (AveragePoo (None, 16, 16, 512)  0           activation_13[0][0]              
__________________________________________________________________________________________________
flatten_1 (Flatten)             (None, 131072)       0           average_pooling2d_1[0][0]        
__________________________________________________________________________________________________
dense_1 (Dense)                 (None, 2)            262144      flatten_1[0][0]                  
__________________________________________________________________________________________________
dense_2 (Dense)                 (None, 101)          13238272    flatten_1[0][0]                  
==================================================================================================
Total params: 24,463,856
Trainable params: 24,456,656
Non-trainable params: 7,200
__________________________________________________________________________________________________

I took the outputted model and used the following script to optimize for inferece:

python -m tensorflow.python.tools.optimize_for_inference --input output_graph.pb --output g.pb --input_names=input_1 --output_names=dense_1/Softmax,dense_2/Softmax

during the operation, the terminal gives me many warnings like this.

 FutureWarning: Conversion of the second argument of issubdtype from `float` to `np.floating` is deprecated. In future, it will be treated as `np.float64 == np.dtype(float).type`.
  from ._conv import register_converters as _register_converters
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (16,), for node batch_normalization_1/FusedBatchNorm
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (128,), for node batch_normalization_2/FusedBatchNorm
WARNING:tensorflow:Didn't find expected Conv2D input to 'batch_normalization_3/FusedBatchNorm'
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (128,), for node batch_normalization_4/FusedBatchNorm
WARNING:tensorflow:Didn't find expected Conv2D input to 'batch_normalization_5/FusedBatchNorm'
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (256,), for node batch_normalization_6/FusedBatchNorm
WARNING:tensorflow:Didn't find expected Conv2D input to 'batch_normalization_7/FusedBatchNorm'
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (256,), for node batch_normalization_8/FusedBatchNorm
WARNING:tensorflow:Didn't find expected Conv2D input to 'batch_normalization_9/FusedBatchNorm'
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (512,), for node batch_normalization_10/FusedBatchNorm
WARNING:tensorflow:Didn't find expected Conv2D input to 'batch_normalization_11/FusedBatchNorm'
WARNING:tensorflow:Incorrect shape for mean, found (0,), expected (512,), for node batch_normalization_12/FusedBatchNorm
WARNING:tensorflow:Didn't find expected Conv2D input to 'batch_normalization_13/FusedBatchNorm'

It seems that these warnings are terrible!!

I have tried both files on my android app. The optimized file is not working at all while the non-optimized file is executable but producing non-sense results "e.g. GUESSING".

I know that the question is a little bit long but it is a summary of whole working day and I do not want to miss any fraction of details.

I do not know where the problem is. Is it in the output nodes names, freezing the graph, instantiating the model with the weights or in optimizing for inference script.

After a research, the problem of random guessing was finally resolved.

The problem was not about converting the model into .pb file as I first expected, but about feeding the image to the model in Android correctly.

I worked on converting the model again. The following points will summarize my work.

First, I got the model from demo.py referenced above in the question. I saved it using the following code: # save the model to .h5 file. model.save('./saved_model/model.h5')
Second, I took the .h5 generated file and convert it to .pb file. I used the code in this repository. The link, in case you could not reach it in the hyperlink,: https://github.com/amir-abdi/keras_to_tensorflow. The code of this repository proves its reliability. It converts the model to .pb file and optimize it for inference at once. It is amazing!
Third, I took the generated .pb file to android assets folder in order to configure it with my application.

Fourth, I converted the intended image to pixel values and did bit-wise shifting to extract colors. getting help with this code to complete this task. Keep in mind that getPixels method preserves colors channels. So, If you need to inverse the color channels follow the following code. I got this help from this answer.

    Bitmap bitmap = createScaledBitmap(faces[0], INPUT_SIZE , INPUT_SIZE , true);
    // get pixel values
    bitmap.getPixels(intValues, 0, bitmap.getWidth(), 0, 0, bitmap.getWidth(), bitmap.getHeight());

    for (int i = 0; i < intValues.length; ++i) {

        final int val = intValues[i];

        // extract colors using bit-wise shifting.
        floatValues[i * 3 + 0] = ((val >> 16) & 0xFF );
        floatValues[i * 3 + 1] = ((val >> 8) & 0xFF );
        floatValues[i * 3 + 2] = (val & 0xFF );

        // reverse the color orderings.
        floatValues[i*3 + 2] = Color.red(val);
        floatValues[i*3 + 1] = Color.green(val);
        floatValues[i*3] = Color.blue(val);
    }