A system includes memory (420) with instructions for at least one of processing spectral CT projection data to mitigate at least one of noise of the spectral CT projection data or a noise induced bias of the spectral CT projection data or generating a decomposition algorithm that mitigates the noise induced bias of the spectral CT projection data. The system further includes a processor (418) that executes the instructions and at least one of processes the spectral CT projection data or generates the decomposition algorithm and decomposes the spectral CT projection data to basis materials. The system further includes a reconstructor (434) that reconstructs the basis materials, thereby generating spectral images.