The knowledge of material specific film grain characteristics can significantly improve the performance of digital film processing algorithms. This paper proposes a rapid and reliable detector for film grain properties. First, homogeneous blocks concerning intensity and texture are determined by a novel measure calculated in the frequency domain. Second, based on these blocks the signaldependent grain noise level is estimated and an image region of pure film grain is detected. Evaluation based on a wide range of structured images with high frequent electronic noise and low frequent film grain, shows that the method performs with a worst case estimation error of 2.54 dB in typical movie quality (PSNR of 25-40 dB). This meets the requirements of real applications such as digital film restoration and special effects compositing.