*improj* - Make a one-dimensional projection of data within a rectangular band traversing an image

This makes a one-dimensional array (or table) giving intensity vs. position. We illustrate with a horizontal band of finite width such as might be used to examine the surface brightness profile of a source or to extract the dispersed spectrum produced by an objective grating.

input file: xdata$rp110590_im1.imh

output file: rp110590_prj.tab

  xr> xspatial 
  xs> improj 

  image file : xdata$rp110590_im1.imh 
  region descriptor : b 231 313 100 10             # a box centered at 231,313 with 
                                                # x dimension=100, y dimension = 10 
  output file .                                                    # uses same root 
  bins in x projection  100 
  bins in y projection  1

The result is a table, rp110590_iml_prj.tab, containing the summed (or average) value of y as a function of x. This can be inspected using sgraph (which is in tables) or tabplot.

  xs> xplot 
  xp> tabplot ``rp110590_im1_prj counts_x''

The task improj will use a rotated box. If the region descriptor is r 231 313 100 10 45 the above box will be rotated 45$^{\circ}$ counter-clockwise. If only a graph of a horizontal or vertical projection is wanted, the task tabplot alone will do this.

  xp> tabplot ``xdata$rp110590_im1[*, 310:319]'' axis=1  # plots sum of y=310--319 
                                                                         # as f(x)