A method and system for providing a dynamic grain effect tool for a media-editing application that generates a grain effect and applies the grain effect to a digital image. The application first generates a random pixel field for the image based on a seed value. The application then generates a film grain pattern for the image by consecutively applying a blurring function and an unsharp masking function, based on an ISO value, to the randomly generated pixel field. The application then blends the grain field with the original image by adjusting each pixel based on the value of the corresponding pixel location in the grain field. The application then adjusts the grain amount in the previously generated full-grain image by receiving a grain amount value from a user and applying this value to the full-grain image.