This paper presents a small-area and low-power circuit implementation of high-precision color space conversion from RGB to YCbCr. Considering the particularity of image data, the paper put forward a novel and efficient common subexpression elimination (CSE) with image data segmentation. Consolidating every part of data appropriately according to the modified CSE algorithm, we will eventually get the transformed YCbCr within the acceptable mean square error (MSE). Besides, the synthesized results of a TSMC 0.18um standard cell library will be given. By using the proposed circuit implementation, the simulation results indicate that the area and power consumption could be 20% less than the conventional Canonic Signed Digital (CSD) method within almost the same accuracy