Unavoidable speckle noise on reconstructed image in laser-based holographic system has been a serious problem in holographic display, due to both temporal and spatial coherence of laser. Employing partially coherent light into optics experiment is an effective way to reduce the speckle noise and thus enhance the signal-to-noise ratio. We will show you the analysis on the coherence of input light, which will affect the quality of the reconstructed image by computer generated hologram (CGH). LED light source with band-pass filters and spatial filters is used to achieve different levels of coherence. The experimental results show high agreement with our analysis. We will also show you how to eliminate the unexpected fringes by employing fast Fourier transform, which can overcome the drawback in our previous proposal with a full analytical algorithm for encoding the CGH of polygonal model. In conclusion, we propose the LED-based holographic imaging system, in order to improve the quality of the holographic imaging.