1. A method for generating an output image of a scene captured by a detector of a task-based imaging system, the detector including a plurality of pixels and the scene including at least one object located at a given object distance within a range of object distances, which object distance is defined as a distance between the object and the task-based imaging system, the method comprising: capturing a high resolution image of the scene over a range of spatial frequencies; converting the high resolution image into an image spectrum of the scene; determining a defocused optical transfer function (OTF) of the task-based imaging system over the range of object distances; determining a pixel modulation transfer function (MTF) over the plurality of pixels of the detector; multiplying the image spectrum with the OTF and the MTF to generate a modified image spectrum of the scene; converting the modified image spectrum into a modified image of the scene; generating the output image from the modified image.