1. A film image reading apparatus comprising: means for illuminating a film on which an image is recorded; means for reading image recorded on the film illuminated by said illuminating means and for outputting image signals representing the image; first detection means for detecting an image density of the image recorded on the film on the basis of the image signals from said reading means; second detection means for detecting a base density of the film on the basis of the image signals from said reading means; means for quantizing the image signals outputted from said reading means; and means for determining a threshold value for quantizing the image signals on the basis of the thus detected image density and base density.