136 lines
3.5 KiB
Groff
136 lines
3.5 KiB
Groff
.TH IM_OPEN 3 "30 October 1992"
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.SH NAME
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im_open, im_open_local, im_open_local_array \- open VIPS
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image descriptor(s)
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.SH SYNOPSIS
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#include <vips/vips.h>
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IMAGE *im_open( const char *filename, const char *mode )
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IMAGE *im_open_local( IMAGE *im, const char *filename, const char *mode )
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int im_open_local_array( IMAGE *im,
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IMAGE **out, int n, const char *filename, const char *mode )
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.SH DESCRIPTION
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.B im_open(3)
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examines the mode string, and creates an appropriate VIPS IMAGE descriptor.
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.B "r"
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opens the named file for reading. If the file is not in the native VIPS format
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for your machine,
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.B im_open(3)
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automatically converts the file for you in memory. For some large files (eg.
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TIFF) this may not be what you want: you should call the appropriate converter
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yourself, and arrange for the conversion to take place on disc. See
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.B im_tiff2vips(3),
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.B im_jpeg2vips(3),
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.B im_png2vips(3),
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.B im_magick2vips(3),
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and
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.B im_ppm2vips(3).
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.B im_open(3)
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can read files in most formats.
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.B "w"
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opens the named file for writing. It looks at the file name suffix to
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determine the type to write -- for example:
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im_open( "fred.tif", "w" )
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will write in TIFF format.
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You can pass parameters to the conversion functions encoded in the filename
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string. For example:
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im_open( "fred.tif:deflate", "w" )
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will write a deflate (ZIP) compressed TIFF file. See the man pages for
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.B im_vips2tiff(3),
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.B im_vips2jpeg(3),
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.B im_vips2png(3)
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and
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.B im_vips2ppm(3)
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for details on all of the options available.
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.B "t"
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creates a temporary memory buffer image.
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.B "p"
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creates a "glue" descriptor you can use to join two image processing
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operations together.
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.B "rw"
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opens the named file for reading and writing. This will only work for VIPS
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files in a format native to your machine. It is only for paintbox-type
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applications.
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.B im_open_local(3)
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is a convenience function which opens an image descriptor as
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im_open(3), but makes it local to im, that is, when im is closed, the
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descriptor created by im_open_local(3) will be closed too.
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.B im_open_local(3)
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is handy for saving you from adding many
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.B im_close(3)
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calls to
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escape points. Example: find the total of an array of images.
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#include <vips/vips.h>
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#include <vips/region.h>
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int
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total( IMAGE **in, int nin, IMAGE *out )
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{
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int i;
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IMAGE *t1, *t2;
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if( nin <= 0 ) {
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im_errormsg( "total: nin should be > 0" );
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return( -1 );
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}
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else if( nin == 1 )
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return( im_copy( *in, out ) );
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else
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for( t1 = *in, i = 1; i < nin; i++ ) {
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if( i + 1 == nin )
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t2 = out;
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else if( !(t2 = im_open_local( out, "t2", "p" )) )
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return( -1 );
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if( im_add( t1, in[i], t2 ) )
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return( -1 );
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t1 = t2;
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}
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return( 0 );
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}
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This function will create many intermediate images, but does not need to close
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them. Any which are created will be closed automatically when out is closed by
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our caller.
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im_open_local(3) returns NULL on error, or if its first parameter is NULL.
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.B im_open_local_array(3)
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will open an array of images, failing if any of the opens fail. It's handy if
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you need a number of images for intermediates. Example:
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IMAGE *t[6];
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if( im_open_local_array( out, t, 6, "mytemps", "p" ) )
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return( -1 );
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opens 6 temp images (t[0] to t[5]).
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.SH RETURN VALUE
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The function returns the image descriptor on success and NULL on error.
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.SH SEE ALSO
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im_close(3), im_vips2tiff(3), im_vips2jpeg(3), im_vips2ppm(3),
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im_tiff2vips(3), im_jpeg2vips(3), im_ppm2vips(3).
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.SH COPYRIGHT
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K. Martinez, 1992.
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.SH AUTHOR
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K. Martinez.
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