I have to send a low resolution image (128x256) from one raspberry pi to another in the fastest way possible. What are some possible ways to approach this problem? Should I send bytes over I2C or set up some kind of LAN connection over which I could transmit (unidirectionally) images between the raspberrys using their IPs? A delay of less than 0.5-1 second is preferable.
Depending on your constraints and whether the two pis are networked, the Dat Protocol is fast, works over a LAN using multicast UDP, and will handle the serialization/deserialization for you.
See also try-dat