Abstract
We analyse a scheme for phase-sensitive amplification of an optical image without using Fourier-transforming lenses, as carried out in a recent experiment. Our analysis shows that the scheme works well with a broadband amplifier, which ensures that the output image is a faithful copy of the object. In addition, when the area of the pixel detector is close to the minimum imaging resolution, both a large output signal-to-noise ratio and noiseless amplification can be realized.