This repo has a python code for changing the splash screen of Yu Yuphoria mobile phone. The splash screen is stored in a file /dev/block/bootdevice/by-name/splash in the mobile phone (You need root access to read this file). Copy this file or you can extract it from the rom of Yu Yuphoria.
For other devices you have to explore the rom for splash file. And also the splash file to get the encoding and offsets