I'm working on a medical Xray images dataset trying to do a binary classification.
After many tries, I have a found a model that can overfit my training set with > 99% accuracy but from the validation curve look it seems like my model has only learned irrelevant details.
What do you think ?
When I try to introduce dropout, training become incredibly slow with bad acc.
If I try image augmentation, results are more promising but of course much slower.
I wonder what to look next:
try running more epochs on the image augmented model
try some medical pretrained model (do you know where to look)
What would you use as parameters for image augmentation (preferably in Keras) with Xray images ?
Related
I trained a model using images I gathered from the web. Then, when inferences were made using images newly collected from the web, performance was poor.
I am wondering how I can improve my dataset using misclassified images. Can I add all the misclassified images to the training dataset? And then do I have to collect new images?
[Edit]
I added some of the misclassified images to the training dataset, although the performance evaluation got better.
It might be worth if you could provide more info on how you trained your model, and your network architecture.
However this are some general guidelines:
You can try to diversify your images in your train set by, yes, adding new images. The more different examples you provide to your network, the higher the chance that they will be similar to images you want to obtain prediction from.
Do data augmentation, it is pretty straightforward and usually improves quite a bit the accuracy. You can have a look at this Tensorflow tutorial for Data Augmentation. If you don’t know what data augmentation is, basically is a technique to perform minor changes to your images, that is by rotating the image a bit, resizing etc. This way the model is trained to learn your images even with slight changes, which usually makes it more robust to new images.
You could consider doing Transfer Learning. The main idea here is to leverage a model that has learned on a huge dataset and use it to fine-tune your specific problem. In the tutorial I linked they show the typical workflow of transfer learning, by taking a model pretrained on the ImageNet dataset (the huge dataset), and retraining it on the Kaggle "cats vs dogs" classification dataset (a smaller dataset, like the one you could have).
I'm training a classification model with custom layers on top of BERT. During this, the training performance of this model is going down with increasing epochs ( after the first epoch ) .. I'm not sure what to fix here - is it the model or the data?
( for the data it's binary labels, and balanced in the number of data points for each label).
Any quick pointers on what the problem could be? Has anyone come across this before?
Edit: Turns out there was a mismatch in the transformers library and tf version I was using. Once I fixed that, the training performance was fine!
Thanks!
Remember that fine-tuning a pre-trained model like Bert usually requires a much smaller number of epochs than models trained from scratch. In fact the authors of Bert recommend between 2 and 4 epochs. Further training often translates to overfitting to your data and forgetting the pre-trained weights (see catastrophic forgetting).
In my experience, this affects small datasets especially as it's easy to overfit on them, even at the 2nd epoch. Besides, you haven't commented on your custom layers on top of Bert, but adding much complexity there might increase overfitting also -- note that the common architecture for text classification only adds a linear transformation.
I'm new in everithing about CNN and tensorflow. Im training a pretrained ssd-mobilenev1-pets.config to detect columns of buildings, about one day but the loss is between 2-1 and doesnt decrease since 10 hours ago.
I realized that my input images are 128x128 and SSD resize de image to 300*300.
Does the size of the input images affect the training?
If that is the case, should I retrain the network with larger input images? or what would be another option to decrease the loss? my train dataset has 660 images and test 166 I dont Know if there are enough images
I really aprecciate your help ....
Loss values of ssd_mobilenet can be different from faster_rcnn. From EdjeElectronics' TensorFlow Object Detection Tutorial:
For my training on the Faster-RCNN-Inception-V2 model, it started at
about 3.0 and quickly dropped below 0.8. I recommend allowing your
model to train until the loss consistently drops below 0.05, which
will take about 40,000 steps, or about 2 hours (depending on how
powerful your CPU and GPU are). Note: The loss numbers will be
different if a different model is used. MobileNet-SSD starts with a
loss of about 20, and should be trained until the loss is consistently
under 2.
For more information: https://github.com/EdjeElectronics/TensorFlow-Object-Detection-API-Tutorial-Train-Multiple-Objects-Windows-10#6-run-the-training
The SSD Mobilnet architecture demands additional training to suffice
the loss accuracy values of the R-CNN model, however, offers
practicality, scalability, and easy accessibility on smaller devices
which reveals the SSD model as a promising candidate for further
assessment (Fleury and Fleury, 2018).
For more information: Fleury, D. & Fleury, A. (2018). Implementation of Regional-CNN and SSD machine learning object detection architectures for the real time analysis of blood borne pathogens in dark field microscopy. MDPI AG.
I would recommend you to take 15%-20% images for testing which cover all the variety present in training data. As you said you have 650+ images for training and 150+ for testing. That is roughly 25% of testing images. It looks like you have enough images to start with. I know the more, the merrier but make sure your model also has sufficient data to learn from!
Resizing the images does not contribute to the loss. It makes sure there is consistency across all images for the model to recognize them without bias. The loss has nothing to do with image resizing as long as every image is resized identically.
You have to make stops and recover checkpoints again and again if you want your model to be perfectly fit. Usually, you can get away with good accuracy by re-training the ssd mobilenet until the loss consistently becomes under 1.Ideally we want the loss to be as lower as possible but we want to make sure the model is not over-fitting. It is all about trial and error. (Loss between 0.5 and 1 seems to be doing the job well but again it all depends on you.)
The reason I think your model is underperforming is due to the fact that you have variety of testing data and not enough training data to suffice.
The model has not been given enough knowledge in training data to make the model learn for new variety of testing data. (For example : Your test data has some images of new angles of buildings which are not sufficiently present in training data). In that case, I recommend you to put variety of all images in training data and then picking images to test making sure you still have sufficient training data of new postures. That's why I recommend you to take 15%-20% test data.
I need a tensorflow model which recognizes a dog's breed. I downloaded the Stanford Dogs Dataset - 20,580 images in 120 categories (=breeds). I followed the procedure described in TensorFlow For Poets to retrain mobilenet_1.0_224. I used --how_many_training_steps=4000 and defaults for everything else. I got this tensorboard graph:
Training and validation accuracy
The validation accuracy is only about 80%.
What can I do to improve it?
In the research paper MobileNets: Efficient Convolutional Neural Networks for Mobile Vision Applications, the test accuracy using the 'MobileNet_1.0_224' architecture on the Stanford Dogs dataset is 83.3%, which seems in line with your results.
When you visually examine the Stanford Dogs Dataset you will find a lot of the breeds look similar, which makes it hard to reach a higher accuracy, even with the state of the art image classifiers in accuracy. You might improve your results by either splitting similar looking breeds into larger subcategories.
Alternatively, you might tweak the training settings of the retrain.py script in the Tensorflow for Poets tutorial, but the gains will be likely be marginal.
So I have trained an object detection model with tensorflow.
I retrained the model (ssd_mobilenet_v2) using a data set containing traffic sign with an image size of 1920x1080 each. The trained model worked really well when ran on desktop.
Now when I ran it on mobile using tfMobile, the Model performed poorly. One thing that stood out to me is that the input for the mobile prediction is reduced to 300x300.
How big of an impact is this? Would retraining the model on images with the same size or aspect ratio improve the model accuracy on mobile?
I also feel like my model is way slower than the one provided from the android demo.