Grain noise in film films and their corresponding repair algorithms are numerous, but they usually have defects, such as smooth transition and high complexity. Combined with the correlation of RGB channels, a noise restoration algorithm based on a sub-regional bilateral filter was developed in this study to eliminate common grain noise in film films and ensure quality assurance for subsequent repair work, such as spots, scratches, image stabilisation, and scintillation. The test results showed that the de-noised image captured using the proposed algorithm not only satisfied the visual requirements of the human eye but also significantly improved the peak signal-to-noise ratio and structural similarity index measure values and decreased the running time to almost half of the original time. These benefits will not only improve the commercial value of old films but will also save a large amount of historical data.