Method for post-processing radar signals with low emission power, in particular for radar of the LPI type (Low Probability of Interception), comprising: - a first step of digitalisation of the analogue signal emitted by the radar and recorded by an interceptor device; - a second step of generating spectra and at least one image, from the digitalised signal obtained in the first step, via FFT processing (Fast Fourier Transform) focusing on low-power signals and recording of the spectra in an image representing on three axes, the frequency on the axis of ordinates, the time on the axis of abscissae and the power of the signal received; said method being characterised in that it also comprises: - a third step of processing the image obtained in the second step, of generating a spectrum and image, said third step comprising at least one substep of detecting the contours of the image arising from step, a substep of thresholding the image processed in the image contour detection step, consisting of changing from an image in a shade of grey to a black-and-white image consisting of binary information for highlighting the detected segments and reducing the noise, a substep of dilating the image processed in the image thresholding step, in order to bridge the gaps in the segments, and a substep of regrouping the detections obtained in the image dilation step; - a fourth step of measurement of segments of the image arising from the image processing step, from the number of contiguous white pixels along the axis of abscissae; - a fifth step of deletion of segments, with a low density of pixels, obtained in the fourth step of measurement, the segments with a high density of pixels being classed as detections in comparison with a given, stored minimum length of time; - and a sixth step of conversion to megahertz and milliseconds of detection of the pixelated signal by a deviation in frequency along the axis of ordinates and by a length of time along the axis of abscissae, obtained in the deletion step, for reading and interpretation. - a first step of digitalisation of the analogue signal emitted by the radar and recorded by an interceptor device; - a second step of generating spectra and at least one image, from the digitalised signal obtained in the first step, via FFT processing (Fast Fourier Transform) focusing on low-power signals and recording of the spectra in an image representing on three axes, the frequency on the axis of ordinates, the time on the axis of abscissae and the power of the signal received; - a third step of processing the image obtained in the second step, of generating a spectrum and image, said third step comprising at least one substep of detecting the contours of the image arising from step, a substep of thresholding the image processed in the image contour detection step, consisting of changing from an image in a shade of grey to a black-and-white image consisting of binary information for highlighting the detected segments and reducing the noise, a substep of dilating the image processed in the image thresholding step, in order to bridge the gaps in the segments, and a substep of regrouping the detections obtained in the image dilation step; - a fourth step of measurement of segments of the image arising from the image processing step, from the number of contiguous white pixels along the axis of abscissae; - a fifth step of deletion of segments, with a low density of pixels, obtained in the fourth step of measurement, the segments with a high density of pixels being classed as detections in comparison with a given, stored minimum length of time; - and a sixth step of conversion to megahertz and milliseconds of detection of the pixelated signal by a deviation in frequency along the axis of ordinates and by a length of time along the axis of abscissae, obtained in the deletion step, for reading and interpretation.