code: def plot_zeropoint(pars):
      
      from matplotlib import pyplot as plt
  
      xp = pars['xp']
      yp = pars['yp']
      searchrad = int(pars['searchrad'] + 0.5)
  
      plt.figure(num=pars['figure_id'])
      plt.clf()
  
      if pars['interactive']:
          plt.ion()
      else:
          plt.ioff()
  
      plt.imshow(pars['data'], vmin=0, vmax=pars['vmax'],
                 interpolation='nearest')
      plt.viridis()
      plt.colorbar()
      plt.title(pars['title_str'])
      plt.plot(xp + searchrad, yp + searchrad, color='red', marker='+',
               markersize=24)
      plt.plot(searchrad, searchrad, color='yellow', marker='+', markersize=120)
      plt.text(searchrad, searchrad, "Offset=0,0", verticalalignment='bottom',
               color='yellow')
      plt.xlabel("Offset in X (pixels)")
      plt.ylabel("Offset in Y (pixels)")
      if pars['interactive']:
          plt.show()
  
      if pars['plotname']:
          suffix = pars['plotname'][-4:]
          output = pars['plotname']
          if '.' not in suffix:
              output += '.png'
              format = 'png'
          else:
              if suffix[1:] in ['png', 'pdf', 'ps', 'eps', 'svg']:
                  format = suffix[1:]
          plt.savefig(output, format=format)
docs: Plot 2d histogram.
  
      Pars will be a dictionary containing:
          data, figure_id, vmax, title_str, xp,yp, searchrad