密集层的输入 0 与该层不兼容：输入形状的预期轴 -1 具有值 8192，但接收到的输入具有形状（无，61608）

Question

I am trying to create an image processing CNN. I am using VGG16 to speed up some of the learning process. The creation of my CNN below works to the point of training and saving the model & weights. The issue occurs when I try to run a predict function after loading in the model.

image_gen = ImageDataGenerator()
train = image_gen.flow_from_directory('./data/train', class_mode='categorical', shuffle=False, batch_size=10, target_size=(151, 136))
val = image_gen.flow_from_directory('./data/validate', class_mode='categorical', shuffle=False, batch_size=10, target_size=(151, 136))

pretrained_model = VGG16(include_top=False, input_shape=(151, 136, 3), weights='imagenet')
pretrained_model.summary()

vgg_features_train = pretrained_model.predict(train)
vgg_features_val = pretrained_model.predict(val)

train_target = to_categorical(train.labels)
val_target = to_categorical(val.labels)

model = Sequential()
model.add(Flatten())
model.add(Dense(100, activation='relu'))
model.add(Dropout(0.5))
model.add(BatchNormalization())
model.add(Dense(2, activation='softmax'))

model.compile(optimizer='rmsprop', metrics=['accuracy'], loss='categorical_crossentropy')

target_dir = './models/weights-improvement'
if not os.path.exists(target_dir):
  os.mkdir(target_dir)

checkpoint = ModelCheckpoint(filepath=target_dir + 'weights-improvement-{epoch:02d}-{val_accuracy:.2f}.hdf5', monitor='val_accuracy', verbose=1, save_best_only=True, mode='max')
callbacks_list = [checkpoint]

model.fit(vgg_features_train, train_target, epochs=100, batch_size=8, validation_data=(vgg_features_val, val_target), callbacks=callbacks_list)

model.save('./models/model')
model.save_weights('./models/weights')

I have this predict function, that I would like to load in an image, and then return the categorisation of this image that the model gives.

from keras.preprocessing.image import load_img, img_to_array
def predict(file):
  x = load_img(file, target_size=(151,136,3))
  x = img_to_array(x)
  print(x.shape)
  print(x.shape)
  x = np.expand_dims(x, axis=0)
  array = model.predict(x)
  result = array[0]
  if result[0] > result[1]:
    if result[0] > 0.9:
      print("Predicted answer: Buy")
      answer = 'buy'
      print(result)
      print(array)
    else:
      print("Predicted answer: Not confident")
      answer = 'n/a'
      print(result)
  else:
    if result[1] > 0.9:
      print("Predicted answer: Sell")
      answer = 'sell'
      print(result)
    else:
      print("Predicted answer: Not confident")
      answer = 'n/a'
      print(result)

  return answer

The issue I am experiencing is when I run this predict function, I get the following error.

  File "predict-binary.py", line 24, in predict
    array = model.predict(x)
  File ".venv\lib\site-packages\tensorflow\python\keras\engine\training.py", line 1629, in predict    
    tmp_batch_outputs = self.predict_function(iterator)
  File ".venv\lib\site-packages\tensorflow\python\eager\def_function.py", line 828, in __call__       
    result = self._call(*args, **kwds)
  File ".venv\lib\site-packages\tensorflow\python\eager\def_function.py", line 871, in _call
    self._initialize(args, kwds, add_initializers_to=initializers)
  File ".venv\lib\site-packages\tensorflow\python\eager\def_function.py", line 725, in _initialize    
    self._stateful_fn._get_concrete_function_internal_garbage_collected(  # pylint: disable=protected-access
  File ".venv\lib\site-packages\tensorflow\python\eager\function.py", line 2969, in _get_concrete_function_internal_garbage_collected
    graph_function, _ = self._maybe_define_function(args, kwargs)
  File ".venv\lib\site-packages\tensorflow\python\eager\function.py", line 3361, in _maybe_define_function
    graph_function = self._create_graph_function(args, kwargs)
  File ".venv\lib\site-packages\tensorflow\python\eager\function.py", line 3196, in _create_graph_function
    func_graph_module.func_graph_from_py_func(
  File ".venv\lib\site-packages\tensorflow\python\framework\func_graph.py", line 990, in func_graph_from_py_func
    func_outputs = python_func(*func_args, **func_kwargs)
  File ".venv\lib\site-packages\tensorflow\python\eager\def_function.py", line 634, in wrapped_fn     
    out = weak_wrapped_fn().__wrapped__(*args, **kwds)
  File ".venv\lib\site-packages\tensorflow\python\framework\func_graph.py", line 977, in wrapper      
    raise e.ag_error_metadata.to_exception(e)
ValueError: in user code:

    .venv\lib\site-packages\tensorflow\python\keras\engine\training.py:1478 predict_function  *       
        return step_function(self, iterator)
    .venv\lib\site-packages\tensorflow\python\keras\engine\training.py:1468 step_function  **
        outputs = model.distribute_strategy.run(run_step, args=(data,))
    .venv\lib\site-packages\tensorflow\python\distribute\distribute_lib.py:1259 run
        return self._extended.call_for_each_replica(fn, args=args, kwargs=kwargs)
    .venv\lib\site-packages\tensorflow\python\distribute\distribute_lib.py:2730 call_for_each_replica 
        return self._call_for_each_replica(fn, args, kwargs)
    .venv\lib\site-packages\tensorflow\python\distribute\distribute_lib.py:3417 _call_for_each_replica
        return fn(*args, **kwargs)
    .venv\lib\site-packages\tensorflow\python\keras\engine\training.py:1461 run_step  **
        outputs = model.predict_step(data)
    .venv\lib\site-packages\tensorflow\python\keras\engine\training.py:1434 predict_step
        return self(x, training=False)
    .venv\lib\site-packages\tensorflow\python\keras\engine\base_layer.py:1012 __call__
        outputs = call_fn(inputs, *args, **kwargs)
    .venv\lib\site-packages\tensorflow\python\keras\engine\sequential.py:375 call
        return super(Sequential, self).call(inputs, training=training, mask=mask)
    .venv\lib\site-packages\tensorflow\python\keras\engine\functional.py:424 call
        return self._run_internal_graph(
    .venv\lib\site-packages\tensorflow\python\keras\engine\functional.py:560 _run_internal_graph      
        outputs = node.layer(*args, **kwargs)
    .venv\lib\site-packages\tensorflow\python\keras\engine\base_layer.py:998 __call__
        input_spec.assert_input_compatibility(self.input_spec, inputs, self.name)
    .venv\lib\site-packages\tensorflow\python\keras\engine\input_spec.py:255 assert_input_compatibility
        raise ValueError(

    ValueError: Input 0 of layer dense is incompatible with the layer: expected axis -1 of input shape to have value 8192 but received input with shape (None, 61608)

I'm assuming I need to change something between the Flatten() and Dense() layers of my model, but I'm not sure what. I attempted to add model.add(Dense(61608, activation='relu)) between these two as that seemed to be what was suggested in another post I saw (cannot find link now), but it lead to the same error. (I tried it with 8192 instead of 61608 as well). Any help is appreciated, thanks.

EDIT #1:

Changing the model creation/training code as I think it was suggested by Gerry P to this

    img_shape = (151,136,3)
base_model=VGG19( include_top=False, input_shape=img_shape, pooling='max', weights='imagenet' )
x=base_model.output
x=Dense(100, activation='relu')(x)
x=Dropout(0.5)(x)
x=BatchNormalization(axis=-1, momentum=0.99, epsilon=0.001)(x)
output=Dense(2, activation='softmax')(x)
model=Model(inputs=base_model.input, outputs=output)

image_gen = ImageDataGenerator()
train = image_gen.flow_from_directory('./data/train', class_mode='categorical', shuffle=False, batch_size=10, target_size=(151, 136))
val = image_gen.flow_from_directory('./data/validate', class_mode='categorical', shuffle=False, batch_size=10, target_size=(151, 136))

vgg_features_train = base_model.predict(train)
vgg_features_val = base_model.predict(val)

train_target = to_categorical(train.labels)
val_target = to_categorical(val.labels)

model.compile(optimizer='rmsprop', metrics=['accuracy'], loss='categorical_crossentropy')

model.fit(vgg_features_train, train_target, epochs=100, batch_size=8, validation_data=(vgg_features_val, val_target), callbacks=callbacks_list)

This resulted in a different input shape error of File "train-binary.py", line 37, in <module> model.fit(vgg_features_train, train_target, epochs=100, batch_size=8, validation_data=(vgg_features_val, val_target), callbacks=callbacks_list) ValueError: Input 0 is incompatible with layer model: expected shape=(None, 151, 136, 3), found shape=(None, 512)

Answer 1

your model is expecting to see an input for model.predict that has the same dimensions as it was trained on. In this case it is the dimensions of vgg_features_train.The input to model.predict that you are generating is for the input to the VGG model. You are essentially trying to do transfer learning so I suggest you proceed as below

base_model=tf.keras.applications.VGG19( include_top=False, input_shape=img_shape, pooling='max', weights='imagenet' )
x=base_model.output
x=Dense(100, activation='relu'))(x)
x=Dropout(0.5)(x)
x=BatchNormalization(axis=-1, momentum=0.99, epsilon=0.001)(x)
output=Dense(2, activation='softmax')(x)
model=Model(inputs=base_model.input, outputs=output)
model.fit( train, epochs=100, batch_size=8, validation_data=val, callbacks=callbacks_list)

now for prediction you can use the same dimensions as you used to train the model.