How to display custom images in TensorBoard using Keras?

Question

I\'m working on a segmentation problem in Keras and I want to display segmentation results at the end of every training epoch.

I want something similar to Tensorflow

Answer 1

I'm trying to display matplotlib plots to the tensorboard (useful incases of plotting statistics, heatmaps, etc). It can be used for the general case also.

class AttentionLogger(keras.callbacks.Callback):
        def __init__(self, val_data, logsdir):
            super(AttentionLogger, self).__init__()
            self.logsdir = logsdir  # where the event files will be written 
            self.validation_data = val_data # validation data generator
            self.writer = tf.summary.FileWriter(self.logsdir)  # creating the summary writer

        @tfmpl.figure_tensor
        def attention_matplotlib(self, gen_images): 
            '''
            Creates a matplotlib figure and writes it to tensorboard using tf-matplotlib
            gen_images: The image tensor of shape (batchsize,width,height,channels) you want to write to tensorboard
            '''  
            r, c = 5,5  # want to write 25 images as a 5x5 matplotlib subplot in TBD (tensorboard)
            figs = tfmpl.create_figures(1, figsize=(15,15))
            cnt = 0
            for idx, f in enumerate(figs):
                for i in range(r):
                    for j in range(c):    
                        ax = f.add_subplot(r,c,cnt+1)
                        ax.set_yticklabels([])
                        ax.set_xticklabels([])
                        ax.imshow(gen_images[cnt])  # writes the image at index cnt to the 5x5 grid
                        cnt+=1
                f.tight_layout()
            return figs

        def on_train_begin(self, logs=None):  # when the training begins (run only once)
                image_summary = [] # creating a list of summaries needed (can be scalar, images, histograms etc)
                for index in range(len(self.model.output)):  # self.model is accessible within callback
                    img_sum = tf.summary.image('img{}'.format(index), self.attention_matplotlib(self.model.output[index]))                    
                    image_summary.append(img_sum)
                self.total_summary = tf.summary.merge(image_summary)

        def on_epoch_end(self, epoch, logs = None):   # at the end of each epoch run this
            logs = logs or {} 
            x,y = next(self.validation_data)  # get data from the generator
            # get the backend session and sun the merged summary with appropriate feed_dict
            sess_run_summary = K.get_session().run(self.total_summary, feed_dict = {self.model.input: x['encoder_input']})
            self.writer.add_summary(sess_run_summary, global_step =epoch)  #finally write the summary!

Then you will have to give it as an argument to fit/fit_generator

#val_generator is the validation data generator
callback_image = AttentionLogger(logsdir='./tensorboard', val_data=val_generator)
... # define the model and generators

# autoencoder is the model, note how callback is suppiled to fit_generator
autoencoder.fit_generator(generator=train_generator,
                    validation_data=val_generator,
                    callbacks=callback_image)

In my case where I'm displaying attention maps (as heatmaps) to tensorboard, this is the output.