A method for processing X-ray image data comprises: receiving sum image data (28) and difference image data (30), wherein the sum image data (28) and the difference image data (30) comprise intensity information of X-rays (18) of two different energies passing through an object (20), the sum image data (28) is based on a sum intensity of the two different energies and the difference image data (30) is based on a difference intensity of the two different energies partitioning the difference image data (30) into a low frequency range (32) and a high frequency range (34) and generating low noise image data (36) by replacing the high frequency range (32) of the difference image (30) with a high frequency range based on the sum image data (28).
