re: Handwritten Digit Recognition Using Convolutional Neural Networks VIEW POST

re: Very well written! Loved the explanations for the pooling and batch normalization. Does dl4j take advantage of GPUs? I did a project on recognizin...

Hi Raunak,

glad you enjoyed the post :) I tried to make it not too theoretical but without some intuition about the math I find it hard to understand how to apply it.

DL4J uses ND4J under the hood for numerical computations on the tensors. ND4J supports native libraries for many different platforms. If you want to use NVIDIA GPUs you can simply use the nd4j-cuda-* dependency. I haven't tried it out, yet, though.

I haven't used keras, yet but I'm planning to check it out later. I also want to try a more sophisticated problem.

I completely agree with your last point about things that the network has never seen before. With CNNs it's very important to pick the right training data and have well-labeled data. In my example I was only rescaling the colors to (0,1) but didn't do any other preprocessing steps. Do you know if, similar to the convolution effect, there are networks that can learn some parts of the preprocessing as well? That would be interesting.

Thanks for your feedback!


Not sure of networks learning the pre-processing as most of the image pipelines I have seen try a lot of hit-and-miss steps with regards to pre-processing. I have seen people try thresholding images, use gradient or edge images, use RGB vs grayscale vs HSL. I think there is a lot of variability in pre-processing which makes it difficult for a network to learn. This is one case where having knowledge of your specific set and some knowledge of computer vision helps, otherwise, we will require a very large number of training images. If we have a small number of images, we can 'augment' the dataset by using image data generators which slightly change images by rotating/resizing/blurring/distorting,etc.

There are also LSTM networks which have a concept of memory but they are used more for speech recognition and time series. I haven't worked with these yet.

Got LSTM on my To-Do list, already. Definately going to check them out!

Thanks Raunak!

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