Photoacoustic (PA) imaging has been widely applied in both preclinical and clinical applications. With a significantly increasing number of data acquisition channels, fast high-quality image reconstruction with low-cost for PA imaging is an open challenge. In this paper, we propose a palm-size PAT system, named palmPAT, to achieve miniaturized low-cost PA imaging modality with high performance. To prove the feasibility, Field Programmable Gate Array (FPGA) implementation of PA image reconstruction is performed to achieve high-quality imaging performance with miniaturized size and cost. This FPGA implementation can be easily adapted to widely used algorithms, such as delay-and-sum (DAS) and its variants (e.g. DMAS, DAS-CF). We have performed in-vivo human finger experiments to demonstrate the feasibility and potential. To our best knowledge, this is the first study concentrated on the implementation and comparison of three frequently-used PA image reconstruction algorithms based on FPGA platform.