[英]VGG16 extremely low accuracy on acne grading
我正在尝试构建一个具有 3 个类别(0 级、1 级、2 级)的 ance 分级分类器。 我在数据集中没有很多图像(每个类大约 500 个)。 因此我使用了 VGG16 预训练的 model。 然而,准确率非常低(~0.33),并且随着训练几乎没有增加。
# Load VGG16 model
vgg_model = VGG16(weights="imagenet",
include_top=False,
input_tensor=Input(shape=(224,224,3)))
vgg_model.summary()
#make the model layers untrainable
for layer in vgg_model.layers:
layer.trainable = False
# Add output layer
output_model = vgg_model.output
output_model = layers.Dropout(0.25)(output_model)
output_model = layers.Flatten()(output_model)
output_model = layers.Dense(128,activation="relu")(output_model)
output_model = layers.Dropout(0.5)(output_model)
output_model = layers.Dense(3,activation="softmax")(output_model)
vggmodel = models.Model(inputs=vgg_model.input, outputs=output_model)
vggmodel.summary()
# Image augmentation on training set
train_datagen = ImageDataGenerator(
rotation_range = 40,
width_shift_range = 0.2,
height_shift_range = 0.2,
shear_range = 0.15,
rescale = 1./255,
)
# only rescale on validation set
validate_datagen = ImageDataGenerator(
rescale = 1./255
)
#set size of batches of data to 64
batch_size = 64
#resizing to 224x224
target_size = (224, 224)
# initialize the training data augmentation object
train_generator = train_datagen.flow_from_directory(directory=training_path, class_mode="categorical",
batch_size=batch_size, target_size=target_size, color_mode='rgb', shuffle= True)
validation_generator = validate_datagen.flow_from_directory(directory=validation_path, class_mode="categorical",
batch_size=batch_size, target_size=target_size, color_mode='rgb', shuffle= True)
vggmodel.compile(loss="categorical_crossentropy", optimizer=SGD(0.01),metrics=["accuracy"])
earlystopping = keras.callbacks.EarlyStopping(monitor ="val_loss",
mode ="min", patience = 2,
restore_best_weights = True)
vggmodel.fit(train_generator, steps_per_epoch=int(1166/batch_size), epochs= 100,
validation_data=validation_generator, validation_steps=5, callbacks=[earlystopping])
我也尝试过构建自己的 model 但性能相似。
input_shape = (224,224,3)
cnn_model = models.Sequential()
cnn_model.add(layers.Conv2D(64, (3, 3), activation='relu',
input_shape=input_shape))
cnn_model.add(layers.Conv2D(64, (3, 3), activation='relu',
input_shape=input_shape))
cnn_model.add(layers.MaxPool2D((2, 2)))
cnn_model.add(layers.Conv2D(64, (3, 3), activation='relu',
input_shape=input_shape))
cnn_model.add(layers.MaxPool2D((2, 2)))
cnn_model.add(layers.Dropout(0.25))
cnn_model.add(layers.Flatten())
cnn_model.add(layers.Dense(128, activation='relu'))
cnn_model.add(layers.Dropout(0.5))
cnn_model.add(layers.Dense(3, activation='softmax'))
cnn_model.summary()
cnn_model.compile(loss="categorical_crossentropy", optimizer=SGD(0.01),metrics=["accuracy"])
earlystopping = keras.callbacks.EarlyStopping(monitor ="val_loss",
mode ="min", patience = 2,
restore_best_weights = True)
cnn_model.fit(train_generator, steps_per_epoch=int(1248/batch_size), epochs= 15,
validation_data=validation_generator, validation_steps=2)
我做错了什么? 对不起,我是初学者:/
做这些,你可能会发现这个错误。
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