1. An active imaging device for imaging a scene, comprising: an illuminator that illuminates said scene with radiation, a radiation detector that detects radiation received from said scene in response to said illumination and that generates detection data from said detected radiation, an image constructor that constructs an image of said scene or one or more parts of said scene from the detection data, a noise reduction unit that processes said image by applying two different pairs of a one- or multi-dimensional transform to the complete image, to one or more parts of the image or to selected features in said image, and a transform selector that selects for the complete image, for one or more parts of the image or for selected features in said image selected pairs of transforms for application by said noise reduction unit resulting in the minimum speckle noise in the image, the respective part or the respective feature of the image, said transform selector separately selecting said selected pairs of transforms based on a predetermined transform selection rule, and said transform selector determining the variance and/or standard deviation of the complete image, of the one or more parts of the image or of the selected features in said image and for selecting the pairs of transforms resulting in the lowest variance and/or lowest standard deviation for the complete image, for one or more parts of the image or for selected features in said image.