Magnetic energy release via field line reconnections is believed to be a major fundamental process in space and astrophysical environments, ranging from accretion disks, flare stars, the sun to the heliosphere and the earth magnetosphere. It is, however, only through solar flare images that we can see direct signatures for the magnetic reconnection. This talk will review recent progresses toward quantitative measurements of the reconnection efficiency using solar images as carried out by NJIT solar group. In most cases, we could utilize the standard two-dimensional reconnection model to derive the reconnection electric field, electric potential and electromagnetic Poynting flux, and thus ultimately the energy release rate during solar flares. In a few exceptional cases, however, we found shortcomings of the two-dimensional model due to the complexity of magnetic topologies, for which we suggest a simple three-dimensional generalization.