In image transmission applications over wireless sensor networks (WSN), energy efficiency and image quality are both important factors for joint optimization. In this paper, we propose a new position-value (P-V) oriented cross layer optimization approach to minimize energy consumption with distortion bounds for image transmission applications in WSN, by exploring importance level diversity for position-magnitude information. To put more effort on transmitting important position information and relatively less effort on unimportant magnitude information, desirable BER, ARQ retry limit, transmission rate and distortion reduction of image are jointly optimized cross PHY, MAC and APP layers, and image quality is assured while energy consumption is minimized. Simulation results demonstrate the effectiveness of the proposed approach in achieving energy efficiency while maintaining image quality.