1. A method of imaging a single unstained sample, comprising: obtaining a spectroscopic image of the single unstained sample; reducing dimensionality of the spectroscopic image, thereby generating reduced spectroscopic image data; and generating an output computed stain image from the reduced spectroscopic image data using a feed-forward neural network trained using reduced spectroscopic data from a group of control samples stained with a target stain as input, wherein the feed-forward neural network generates bright-field color data as output.