Deep Feed Forward Neural Network is one of the type of Artificial Neural Networks, which is also able to classify computer images.
In order to feed pixel data into the neural net in RBG/Greyscale/other format one can map every pixel to network inputs.
That means every pixel becomes a feature. It may sound scary and highly inefficient to feed, let's say, 28 hieght on 28 width image size, which is 784 features to learn from.
However, neural networks can learn from the pixel data successfully and classify unseen data. We are going to prove this.
Please note, there are additional type of networks which are more efficient in image classification such as Convolutional Neural Network, but we are going to talk about that next time.