How are data in tensorflow.examples.tutorials.mnist formatted? I am analyzing a sample code that implements a Restricted Boltzmann Machine (RBM) using Tensorflow. The input data seems to be the good old MNIST, except that apparently, it is now available in Tensorflow itself.

So, instead of running this sample code on MNIST, I want to run it on my own data. But the problem is that I do not know how 


  tensorflow.examples.tutorials.mnist


has been formatted. Is it like a CSV file? If I want to feed my own data, which comes from Wizemann's horse images, how should I format my data that is compatible with how MNIST has been formatted?

I'm very new to this stuff. So, please enlighten me if I am mistaken or my question is absurd.
Based on the official documentation after loading the data,

from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets("MNIST_data/", one_hot=True)


You can use the following line,

mnist.train.images.shape


to see the shape of images, as you can see it is a rank-2 matrix which means images are unrolled which one dimension specifies the number of examples and another specifies the number of pixels __features.