Что вам нужно, сеть с двумя входами и одним выходом, где каждый вход имеет свое собственное извлечение признаков и обе функции объединены перед предсказанием окончательного выхода.
Ниже приведен пример.
import keras
from keras.applications.vgg19 import VGG19
from keras.layers import Input, Dense, Concatenate
from keras.models import Model
#-------------------------------------------------------------------------------
# Define your new inputs
# Here I pretend that your new task is a classification task over 100 classes
#-------------------------------------------------------------------------------
gender_input = Input(shape=(1,), name='gender_input')
image_input = Input(shape=(224,224,3), name='image_input')
num_classes = 100
#-------------------------------------------------------------------------------
# define your pretrained feature extraction
# you may do something different than below
# but the point here is to have a pretrained model for `featex`
# so you may define it differently
#-------------------------------------------------------------------------------
pretrained = VGG19()
featex = Model( pretrained.input, pretrained.layers[-2].output, name='vgg_pop_last' )
# consider to freeze all weights in featex to speed-up training
image_feat = featex( image_input )
#-------------------------------------------------------------------------------
# From here, you may play with different network architectures
# Below is just one example
#-------------------------------------------------------------------------------
image_feat = Dense(128, activation='relu', name='image_fc')( image_feat )
gender_feat = Dense(16, activation='relu', name='gender_fc')( gender_input )
# mix information from both information
# note: concatenation is only one of plausible way to mix information
concat_feat = Concatenate(axis=-1,name='concat_fc')([image_feat, gender_feat])
# perform final prediction
target = Dense(num_classes, activation='softmax', name='pred_class')( concat_feat )
#-------------------------------------------------------------------------------
# Here is your new model which contains two inputs and one new target
#-------------------------------------------------------------------------------
model = Model( inputs=[image_input, gender_input], outputs=target, name='myModel')
print model.summary()