Color of ghost imaging

In this paper, we investigate the color of ghost imaging with thermal and quantum sources. We find that the color of ghost imaging is a composite color that depends on the object and reference fields, which is different from the classical optical imaging. Furthermore, we find that the color of ghost image can be different from the color of the light interacted with the object, which is not achieved in the classic optical imaging. Generally, we can only obtain the monochromatic ghost image by the quantum ghost imaging, while the monochromatic and color ghost image can be obtained by the ghost imaging with thermal source.