Wireless Sensor Network (WSN) has limited resources such as energy, computation and transmission capacity. These resources are not sufficient for transmitting large amount of data collected by the sensor nodes. Wireless Multimedia Sensor Network (WMSN) generates large amount of data that requires more energy and transmission capacity as compared to scalar data. So it is desired to perform in-network data compression in WMSN. In this paper the authors have used Principal Component Analysis (PCA) technique for data compression. PCA can be efficiently used in wireless multimedia sensor network to reduce the energy consumption, reduce the network load and prolong the network lifetime. Simulation results show that PCA based compression conserves energy of sensor nodes and prolongs the lifetime of WMSN.