I am going to build a mushroom identification application and using neural networks for image classification. Right now I am thinking about different image processing methods to implement before feeding my data (mushroom pictures) to the neural network. As one solution I have stumbled into background subtraction, which sounds rather sensible solution as almost all mushroom pictures have forest (similar) background. Yet I have not found any adequate proof that it is used in image classification.
So my question is, whether it is a common practice to remove background from images before using them to train neural network for image classification?