  In this paper, we present an interpolation scheme for FRQI images based on
bilinear interpolation. To accomplish this, we formulated several quantum
modules, i.e., assignment module, increment module, and quarter module, and
suffused them into our proposed quantum image interpolation circuit. The
concrete quantum circuits to accomplish up-scaling and down-scaling based on
bilinear for FRQI images are designed and the network complexities of them are
analyzed. Finally, to validate the proposed method, simulation experiments to
enlarge and reduce the test images are executed, whose results are compared
with the nearest neighbor interpolation for FRQI images. The up-scaled images
by using proposed interpolation algorithm achieve satisfactory results, and
both PSNR and SSIM values are better than those of the nearest neighbor method.
