Modify a Convolutional Neural Network

Hello,

I am working on a task related to image classification. I want to modify my CNN and add a HOG feature extractor in parallel with the convolution layers extraction process and at the end concatenate all the feature and apply the training of the network:

trainNetwork(augmentedTrainingSet, network, opts);

To apply this modification and get a new CNN model that could be trained end-to-end, I need a new layer that will apply the HOG extraction.

How can I create a layer that will extract, which i can add to the CNN model ? :

features = extractHOGFeatures(I);

I don't know if my idea is clear but I attached a picture explaining the concept. I will appreciate any kind of help!

Thank you in advance,