int im_ppm2vips( const char *filename, IMAGE *out )
int im_ppm2vips_header( const char *filename, IMAGE *out )
int im_vips2ppm( IMAGE *in, const char *filename )
im_ppm2vips_header() reads the just the header of the image into the VIPS image. You can’t read any pixels!
im_vips2ppm() writes the VIPS image to the named file in PPM format. It can write 8, 16 or 32 bit integer images, colour or monochrome, stored as binary or ASCII. Images of more than 8 bits can only be stored in ASCII.
The storage format is indicated by a filename extension.
im_vips2ppm( im, "fred.ppm:ascii" )
will write to "fred.ppm" in ascii format. The default is binary.