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SGI Developer Toolbox 6.1
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SGI Developer Toolbox 6.1 - Disc 4.iso
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filter.hlp
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1994-08-01
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@C1@c@b@_ External Filters
Pipe the current image thru an external filter and replace the current
image with the filtered one.
@b Definitions
A filter is defined as an external program that reads at least one
of the BIT supported formats from argv[1] and output the (possibly)
transformed image to stdout. All external filter definitions must
start with the at (@) sign and any line that does not is silently
ignored.
A filter definition should have the following format
@f @title; name; options; in1;[in2;[in3;]]
where title is the text to use to label the activation button and name
and options are the command and option to use in the popen(3S)
system call; in{[1-3]} is the accepted formats for the program.
If the option field contains a single question mark "?", a string
will be prompted before the external program is run. If title is empty,
the program name is used to label the button. The following is a valid
filter definition
@f @rotate45 ; pnmrotate; 45 ; ppm; pgm; pbm;
Also See /usr/local/lib/bit/BIT_filters for some examples
@b File Locations
The external filter definition should be in a file named BIT_filters.
The program will search the system directory, /usr/local/lib/bit,
current directory, and ~/.bitrc/ (or environment variable BITDIR)
in that order for BIT_filters.
@b Special Note
The input format should be in order of decreasing generality,
i.e., ppm; pgm; pbm.