1. A non-transitory, computer-readable storage medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: receiving an image; comparing the image to a plurality of reference images; selecting a reference image from the plurality of reference images that is the most similar to the image; generating a delta image representing a difference between the reference image and the image; storing the delta image with a reference to the reference image; and balancing a number of reference images stored with a number of delta images stored to maintain one or more of: a predetermined ratio of reference images to delta images; or a predetermined ratio of average delta image size to average reference image size.