1. A method for image editing, applicable to a system for image editing comprising a source device and a processor, wherein the method is executed by the processor and comprises: (a) the processor dividing a color image provided by the source device into a plurality of components corresponding to a color space; (b) the processor searching for characteristic curves in each of the components of the color image; (c) the processor establishing corresponding relationship among the characteristic curves in different components of the color image but at a same position; (d) the processor approximating the characteristic curves with spline functions; (e) the processor manipulating at least one of the characteristic curves through control points of the corresponding spline functions; (f) the processor manipulating the characteristic curves having a corresponding relationship with the manipulated characteristic curve in the same way; and (g) the processor reconstructing the color image according to the characteristic curves of the color image.