docs: def _setup_cmd(self,mode='cloud-in-cells'):
          """
          The purpose here is to create a more finely binned
          background CMD to sample from.
          """
          # Only setup once...
          if hasattr(self,'bkg_lambda'): return
  
          logger.info("Setup color...")
          # In the limit theta->0: 2*pi*(1-cos(theta)) -> pi*theta**2
          # (Remember to convert from sr to deg^2) 
          #solid_angle_roi = sr2deg(2*np.pi*(1-np.cos(np.radians(self.roi_radius))))
          solid_angle_roi = self.roi.area_pixel*len(self.roi.pixels)
  
          # Large CMD bins cause problems when simulating
          config = Config(self.config) 
          config['color']['n_bins'] *= 5 #10
          config['mag']['n_bins']   *= 1 #2
          #config['mask']['minimum_solid_angle'] = 0
          roi = ugali.analysis.loglike.createROI(config,self.roi.lon,self.roi.lat)
          mask = ugali.analysis.loglike.createMask(config,roi)
  
          self.bkg_centers_color  = roi.centers_color
          self.bkg_centers_mag    = roi.centers_mag
  
          # Background CMD has units: [objs / deg^2 / mag^2]
          cmd_background = mask.backgroundCMD(self.catalog,mode)
          
          self.bkg_lambda=cmd_background*solid_angle_roi*roi.delta_color*roi.delta_mag
          np.sum(self.bkg_lambda)
  
          # Clean up 
          del config, roi, mask