A subset of the STL10 Dataset (stlSubset.zip)

In all the exercises so far, you have been working only with grayscale images. In this exercise, you will get to work with RGB color images for the first time. Conveniently, the fact that an image has three color channels (RGB), rather than a single gray channel, presents little difficulty for the sparse autoencoder. You can just combine the intensities from all the color channels for the pixels into one long vector, as if you were working with a grayscale image with 3x the number of pixels as the original image.