Abstract
Astronomical images obtained from existing cameras are subjected to various types of noise artifacts. Impulse noise is one of them and it is visible as dark and bright spots on the image. Common practice to remove impulse noise is to perform averaging of several frames. This will increase signal-to-noise ratio of the image, however, impulse noise might still be present. The noisy image will hinder the performance of further processing operations such as edge detection. In this brief, variable pixel G-neighbor temporal filtering circuit is proposed to improve the quality of astronomical images with the impulse noise. As compared to conventional averaging of frames in the time domain, where all pixels are summed, the proposed circuit select pixels in each frame that are closest to the reference pixel. The circuit operates in the analog domain, and it was designed and tested using 180-nm CMOS technology. Simulations demonstrate improvement in the peak-signal-to-noise (PSNR) ratio, mean-squared-error (MSE) and structural similarity index measure (SSIM) as compared to conventional averaging of frames.