ValueError：检查目标时出错：期望的model_2具有形状（无，252,252,1）但是具有形状的数组（300,128,128,3）

Question

嗨我正在为一类分类构建图像分类器，其中我在运行此模型时使用了自动编码器，我通过此行获取此错误（autoencoder_model.fit）（ValueError：检查目标时出错：预期model_2具有形状（无，252,252,1）但是有阵列形状（300,128,128,3）。）

num_of_samples = img_data.shape[0]
labels = np.ones((num_of_samples,),dtype='int64')



labels[0:376]=0 
names = ['cats']


input_shape=img_data[0].shape



X_train, X_test = train_test_split(img_data, test_size=0.2, random_state=2)


inputTensor = Input(input_shape)
x = Conv2D(16, (3, 3), activation='relu', padding='same')(inputTensor)
x = Conv2D(8, (3, 3), activation='relu', padding='same')(x)
x = MaxPooling2D((2, 2), padding='same')(x)
x = Conv2D(8, (3, 3), activation='relu', padding='same')(x)
encoded_data = MaxPooling2D((2, 2), padding='same')(x)

encoder_model = Model(inputTensor,encoded_data)

# at this point the representation is (4, 4, 8) i.e. 128-dimensional
encoded_input = Input((4,4,8))
x = Conv2D(8, (3, 3), activation='relu', padding='same')(encoded_input)
x = UpSampling2D((2, 2))(x)
x = Conv2D(8, (3, 3), activation='relu', padding='same')(x)
x = UpSampling2D((2, 2))(x)
x = Conv2D(16, (3, 3), activation='relu',padding='same')(x)
x = UpSampling2D((2, 2))(x)
decoded_data = Conv2D(1, (3, 3), activation='sigmoid', padding='same')(x)

decoder_model = Model(encoded_input,decoded_data)

autoencoder_input = Input(input_shape)
encoded = encoder_model(autoencoder_input)
decoded = decoder_model(encoded)
autoencoder_model = Model(autoencoder_input, decoded)
autoencoder_model.compile(optimizer='adadelta', 
 `enter code here`loss='binary_crossentropy')


autoencoder_model.fit(X_train, X_train,
            epochs=50,
            batch_size=32,
            validation_data=(X_test, X_test),
            callbacks=[TensorBoard(log_dir='/tmp/autoencoder')])

Answer 1

这是解码器的输出形状与训练数据的形状之间的简单不兼容性。 （目标是指输出）。

我看到你有2个MaxPoolings（将你的图像大小除以4）和三个上采样（将解码器的输入乘以8）。

自动编码器的最终输出太大，与您的数据不匹配。您必须简单地在模型中工作才能使输出形状与您的训练数据相匹配。

Answer 2

您使用的是错误的API

autoencoder_model.fit(X_train, X_train,  <--- This one is wrong
        epochs=50,
        batch_size=32,
        validation_data=(X_test, X_test),
        callbacks=[TensorBoard(log_dir='/tmp/autoencoder')])

看一下https://github.com/keras-team/keras/blob/master/keras/models.py的.fit方法源代码

def fit(self,
        x=None,
        y=None,
        batch_size=None,
        epochs=1,
        verbose=1,
        callbacks=None,
        validation_split=0.,
        validation_data=None,
        shuffle=True,
        class_weight=None,
        sample_weight=None,
        initial_epoch=0,
        steps_per_epoch=None,
        validation_steps=None,
        **kwargs):
    """Trains the model for a fixed number of epochs (iterations on a dataset).
    # Arguments
        x: Numpy array of training data.
            If the input layer in the model is named, you can also pass a
            dictionary mapping the input name to a Numpy array.
            `x` can be `None` (default) if feeding from
            framework-native tensors (e.g. TensorFlow data tensors).
        y: Numpy array of target (label) data.
            If the output layer in the model is named, you can also pass a
            dictionary mapping the output name to a Numpy array.
            `y` can be `None` (default) if feeding from
            framework-native tensors (e.g. TensorFlow data tensors).

所以x应该是数据，y应该是数据的标签。希望有所帮助