1. In an X-ray system arranged to display a first picture of an object generated in response to an X-ray first range of energy levels and an X-ray second range of energy levels different from the first range of energy levels and arranged to display a second picture of the object generated in response to substantially a single range of X-ray energy levels, a method for adjusting a contrast level of the first picture relative to a contrast level of the second picture comprising: transmitting X-rays at the first range of energy levels and the second range of energy levels to generate a first image representing the object in response to the first range of energy levels and to generate a second image representing the object in response to the second range of energy levels; obtaining a first decomposed image from the first and second images according to a first decomposition algorithm; obtaining a second decomposed image from the first and second images according to a second decomposition algorithm; computing a contrast adjusted image in response to the first and second decomposed images; displaying the first picture in response to the contrast adjusted image; and displaying the second picture.