In this paper, we presents a framework for hardware accelerating methods for video post processing system implemented on FPGA. The histogram equalization and image-sharpening filter are the algorithms ported onto the SOC having Altera NIOS-II soft processor. Custom instructions are chosen by identifying the most frequently used tasks in the algorithm and the instruction set of NIOS-II processor has been extended. Saturation and the Histogram are the new instructions added to the processor that are implemented in hardware and interfaced to the NIOS-II processor. The software implementation of the algorithms has been modified to use the new instructions added for computing the saturation and histogram calculation. Performance of the software implementation of the histogram equalization and sharpening algorithms is boosted by these new instructions added to the NIOS-II processor. The comparison shows that the implemented tasks have been accelerated by -multiple‖ times. The saturation instruction is generic instruction, which can be used in many Image processing applications. The benefit of speed is obtained at the cost of very small hardware resources.