It is possible to upscale a digitally filmed 1080p movie to 4K resolution, but the results may not be as good as a true 4K film. This is because 4K resolution has four times the number of pixels as 1080p, so simply increasing the size of the image will not result in the same level of detail. There are various techniques that can be used to upscale a 1080p film to 4K, including using artificial intelligence algorithms to analyze the image and add new pixels to create a higher resolution version. However, these methods can only do so much and the resulting image will not be as sharp or detailed as a true 4K film. It is important to note that the quality of the original source material will also play a role in the effectiveness of upscaling. A well-restored 1080p film may produce better results when upscaled to 4K than a poorly restored or low-quality 1080p film.