Example processing of ROSAT HRI data from NGC 6240. Pixels are 8 arcsec². Axes are labeled in terms of pixels, with ﹩( 0,0) ﹩ roughly being the location of NGC 6240. Count levels have been truncated for clarity; the actual peak count level in this data set is ~100. (a) Raw data. (b) Data smoothed by a Gaussian of ﹩\sigma =2﹩ pixels. (c) TIPSH denoised data, using calibrated thresholds of eq. (3), an average background level estimated from the data, and the hard‐thresholding nonlinearity. (d) Result from the heuristic hypothesis‐free approach.