Keras custom dataset with images as label/ground truth - image

Question

I'm making a model for image denoising and use ImageDataGenerator.flow_from_directory to load the dataset. It is structured in two folders, one with noisy input images and one with the corresponding clean images. I want the generator to use the images in the first folder as inputs and the other folder as "labels"/ground truth.
With the method I'm using right now all images in both folders are treated as inputs with the folder name as label. I can extract the images manually by selecting specific batches and train on that, but it's inconvenient and probably wasn't intended to be used that way.
What is the proper way of doing this? There probably is a function for this but I can't find it.

Answer 1

Had similar problem. Found it necessary to create a custom generator to feed the images into model.fit. Code (rather lengthy) is posted below.
import os
import pandas as pd
import numpy as np
import glob
import cv2
from sklearn.model_selection import train_test_split
def create_df(image_dir, label_dir, shuffle=True):
path=image_dir + '/**/*'
image_file_paths=glob.glob(path,recursive=True)
path=label_dir + '/**/*'
label_file_paths=glob.glob(path,recursive=True)
# run a check and make sure filename without extensions match
df=pd.DataFrame({'image': image_file_paths, 'label':label_file_paths}).astype(str)
if shuffle:
df=df.sample(frac=1.0, replace=False, weights=None, random_state=123, axis=0).reset_index(drop=True)
return df
class jpgen():
batch_index=0 #tracks the number of batches generated
def __init__(self, df, train_split=None, test_split=None):
self.train_split=train_split # float between 0 and 1 indicating the percentage of images to use for training
self.test_split=test_split
self.df=df.copy() # create a copy of the data frame
if self.train_split != None: # split the df to create a training df
self.train_df, dummy_df=train_test_split(self.df, train_size=self.train_split, shuffle=False)
if self.test_split !=None: # create as test set and a validation set
t_split=self.test_split/(1.0-self.train_split)
self.test_df, self.valid_df=train_test_split(dummy_df, train_size=t_split, shuffle=False)
self.valid_gen_len=len(self.valid_df['image'].unique())# create var to return no of samples in valid generator
self.valid_gen_filenames=list(self.valid_df['image'])# create list ofjpg file names in valid generator
else: self.test_df=dummy_df
self.test_gen_len=len(self.test_df['image'].unique())#create var to return no of test samples
self.test_gen_filenames=list(self.test_df['image']) # create list to return jpg file paths in test_gen
else:
self.train_df=self.df
self.tr_gen_len=len(self.train_df['image'].unique()) # crete variable to return no of samples in train generator
def flow(self, batch_size=32, image_shape=None,rescale=None,shuffle=True, subset=None ):
# flows batches of jpg images and png masks to model.fit
self.batch_size=batch_size
self.image_shape=image_shape
self.shuffle=shuffle
self.subset=subset
self.rescale=rescale
image_batch_list=[] # initialize list to hold a batch of jpg images
label_batch_list=[] # initialize list to hold batches of png masks
if self.subset=='training' or self.train_split ==None:
op_df=self.train_df
elif self.subset=='test':
op_df=self.test_df
else:
op_df=self.valid_df
if self.shuffle : # shuffle the op_df then rest the index
op_df=op_df.sample(frac=1.0, replace=False, weights=None, random_state=123, axis=0).reset_index(drop=True)
#op_df will be either train, test or valid depending on subset
# develop the batch of data
while True:
label_batch_list=[]
image_batch_list=[]
start=jpgen.batch_index * self.batch_size # set start value of iteration
end=start + self.batch_size # set end value of iteration to yield 1 batch of data of length batch_size
sample_count=len(op_df['image'])
for i in range(start, end): # iterate over one batch size of data
j=i % sample_count # used to roll the images back to the front if the end is reached
k=j % self.batch_size
path_to_image= op_df.iloc[j]['image']
path_to_label= op_df.iloc[j] ['label']
label_image=cv2.imread(path_to_label, -1) # read unchanged to preserve 4 th channel print (png_image.)
label_image= cv2.cvtColor(label_image, cv2.COLOR_BGR2RGB)
image_image=cv2.imread(path_to_image)
image_image= cv2.cvtColor(image_image, cv2.COLOR_BGR2RGB)
label_image=cv2.resize(label_image, self.image_shape)
image_image=cv2.resize(image_image, self.image_shape )
if rescale !=None:
label_image=label_image * self.rescale
image_image=image_image * self.rescale
label_batch_list.append(label_image)
image_batch_list.append(image_image)
image_array=np.array(image_batch_list)
label_array=np.array(label_batch_list)
jpgen.batch_index +=1
yield (image_array, label_array)
Code below shows how to use the functions above to make generators for model.fit
image_dir=r'C:\Temp\gen_test\images'# directory with clean images
label_dir=r'C:\Temp\gen_test\labels' # directory with noisy images file names same as filenames in clean dir
shuffle=False # if True shuffles the dataframe
df=create_df(image_dir, label_dir ,shuffle) # create a dataframe with columns 'images' , 'labels'
# where labels are the noisy images
train_split=.8 # use 80% of files for training
test_split=.1 # use 10% for test, automatically sets validation split at 1-train_split-test_split
batch_size=32 # set batch_size
height=224 # set image height for generator output images and labels
width=224 # set image width for generator output images and labels
channels=3 # set number of channel in images
image_shape=(height, width)
rescale=1/255 # set value to rescale image pixels
gen=jpgen(df, train_split=train_split, test_split=test_split) # create instance of generator class
tr_gen_len=gen.tr_gen_len
test_gen_len= gen.test_gen_len
valid_gen_len=gen.valid_gen_len
test_filenames=gen.test_gen_filenames # names of test file paths used for training
train_steps=tr_gen_len//batch_size # use this value in for steps_per_epoch in model.fit
valid_steps=valid_gen_len//batch_size # use this value for validation_steps in model.fit
test_steps=test_gen_len//batch_size # use this value for steps in model.predict
# instantiate generators
train_gen=gen.flow(batch_size=batch_size, image_shape=image_shape, rescale=rescale, shuffle=False, subset='training')
valid_gen=gen.flow(batch_size=batch_size, image_shape=image_shape, rescale=rescale, shuffle=False, subset='valid')
test_gen=gen.flow(batch_size=batch_size, image_shape=image_shape, rescale=rescale, shuffle=False, subset='test')
Build your model then use
history=model.fit(train_gen, epochs=epochs, steps_per_epoch=train_steps,validation_data=valid_gen,
validation_steps=valid_steps, verbose=1, shuffle=True)
predictions=model.predict(test_gen, steps=test_steps)