README for infile= option of supsimage.

Demo shell scripts:

Attributes	compute trace attributes and plot these on an suximage
		of seismic wave data
Poynting_Vector		display the Poynting vector of seismic wave 
			energy on a seismic wave plot	

Ekkehart Tessmer's original documentation for the infile= feature
for psimage and supsimage.

			Documentation for (SU)PSIMAGE
			==============================

	PSIMAGE is modified to allow the display of STDIN to be 
        modulated by a second attribute.

	In this way it is possible to display an array, of e.g. angles,
	where those parts of the image will be faded out where the 
	amplitudes of the second attribute are low, i.e. where the image
	would be meaningless. The faded area appear more or less gray.

	In other words the program mimics to display STDIN in front of a 
	gray background using 'infile' as an alpha-channel to control
	transparency.

	The second attribute is input to PSIMAGE by the command-line 
	parameter 'infile=<filename>'. The gray value can be chosen by the
	command-line parameter 'bckgr=<value between 0.0 and 1.0>'. 
	The extreme values 0.0 and 1.0 mean black and white background, 
	respectively.



	Notes:

	The amplitudes of 'infile' must be from the range 0.0 - 1.0.
	This is checked by the program.

	The number of samples and traces (n1,n2) of 'infile' must be the 
	same as those of STDIN.

	If 'infile=<filename>' is not present in the command line then
	PSIMAGE behaves like PSIMAGE.

	For a high-quality plot it is recommended to include 'bps=24' 
	into PSIMAGE's command-line parameter list. However, this doubles
	the size of the PostScript output file.

	
	There are two examples showing the new functionality.
	
	E.T. 13.03.2010
