This invention provides a dynamic image adjusting apparatus for dynamically adjusting the contrast of a first image signal which includes a plurality of pixels. The adjusting apparatus includes a first transformation module, an operation module, and a second transformation module. The first transformation module receives the first image signal for generating a plurality of adjusting signals, wherein each pixel of the first image signal corresponds to one of the plurality of adjusting signals. The operation module is coupled to the first transformation module and receives a first set of adjusting signals of the plurality of adjusting signals to generate a first gain curve. The second transformation module is coupled to the operation module and the first transformation module, and generates a second image signal according to the first gain curve and the plurality of adjusting signals.