1. 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 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 a selected transform 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.