Exploratory Data Analysis with Image Datset
Have a look at The HASYv2 dataset. I tried to do as much of the exploratory work as possible to make sure that others can directly try more interesting thing with the dataset.

Image format specific stuff


(Minimum / Median / Mean / Maximum) (width / height / area)
Image formats
Timestamps
Exiff meta data


For this kind of stuff, you might want to have a look at edapy.

Image/ML specific stuff

Things you can do with images:


Compute the mean image


Mean image by class

Eigenfaces (or rather "Eigenimages")
Fisher-Faces


You can compute the correlation of pixels, e.g. Figure 3:



Classification-specific stuff


Plot the distribution of classes.
Behaviour of standard classification algorithms (CNNs, VGG-16)
Confusion Matrix Ordering (page 48 - 52, especially Figure 5.12 and 5.13): Find similar classes