1. A method for processing an image, comprising: using an image processor: obtaining a luma image based upon image data acquired using an image sensor; for each luma pixel of the luma image, applying a multi-scale unsharp mask filter to a current luma pixel to determine one or more unsharp values, wherein each of the one or more unsharp values is associated with a respective gain and a respective threshold; determining a base value, wherein the base value is selected as either a value of the current luma pixel or as a value of an output of the multi-scale unsharp mask filter based at least partially upon a noise variance of the image data; comparing each of the one or more unsharp values to the respective threshold; for each of the one or more unsharp values that is greater than the respective threshold, applying the respective gain to determine corresponding gained unsharp values; and adding each gained unsharp value to the base value to produce a sharpened pixel corresponding to the current luma pixel.