<p>A coding method comprises the steps of: receiving the data to be transformed; implementing a first transform to the received data and obtaining a first transformed data; implementing a second transform to the received data and obtaining a second transformed data; determining an adjusting parameter based on the first transformed data and the second transformed data; adjusting the first transformed data according to the adjusting parameter and the parameter of the second transform. A method for decoding and a device, system for coding and decoding are also provided. The value range of the transformed data is adjusted so that the value range ofimage data transformed by different transforms can keep consistent and the influence caused by the transforms can be reflected truly when the adaptive block transform technique is adopted. The transform with preferred effect can be selected to improve the coding efficiency.</p>
