fil_ter - file filter, allows for operations on the phase or intensity arbitrarily.

Calling Sequence

[field_out]=fil_ter(field_in,c1,c2,fname[,norm])

Parameters

• field_in :input field. it must be diffractive wavefront.
• c1 : character constant with valid values 'int' and 'pha'.
• c2 : character constant with valid values 'mult' and 'subst'
• fname : the name of a file containing intensity/phase mask. It may be portable graymap or anymap (*.pgm, *.pnm)with grayscale data. the Matrix data of the fname must have the same dimensions as field_in.
• norm : default norm = 0. argument indicating if the intensity mask should be normalized before applying.
• field_out : the output field or diffractive wavefront.

Description

The files include phase and intensity distributions may be produced with a SAO function itself. File_int , file_pha and file_pgm provide such a possibility. The dimensions of the exported and imported distributions must be the same (this can be fixed with interpol ), otherwise the behavior is not defined. Any (square) file (gif,tiff, bmp) containing graphics, can be converted into pgm format - for example using xv , and imported by fil_ter as the intensity or the phase distribution.

some examples(we suppose field_in=f):

fil_ter (f,"int","mult","aa"): filter through intensity mask from file aa.

fil_ter (f,"pha","subst","aa"): substitute the phase with phase taken from file aa

fil_ter (f,"pha","mult","aa"): filter the field through phase filter aa

fil_ter (f,"int","subst","aa"): substitute intensity with one taken from file aa

fil_ter (f,"int","subst","aa",1): substitute intensity with a normalized one taken from file aa

Examples

	f1=begin(0.01,1e-6);
	f2=gauss(f1,0.004);
	
	file_int(f2,"file",-1,0,1);	
	file_pgm(f2,"file",-1,2,0);
	
	f3=fil_ter(f1,"int","mult","file.txt");	
	f4=fil_ter(f3,"pha","subst","file.pgm");
	
	field_plot(f4);	
 

Author

Chen jingyuan, Gan guangyong (IAPCM, Beijing,China.)

See Also

pip_fft ,