All options can be abbreviated to their shortest unique prefix. You may use two hyphens instead of one. You may separate an option name and its value with white space instead of an equals sign.
This program is part of Netpbm.
pnmstitch stitches together two panoramic photographs. This means if you have photographs of the left and right side of something that is too big for a single camera frame, pnmstitch can join them into one wide picture.
pnmstitch works only on side-by-side images, not top and bottom (though you could certainly use pamflip in combination with pnmstitch to achieve this). It stitches together two images, but you can use it repeatedly to stitch together as many as you need to.
Your photographs must overlap in order for pnmstitch to work, and the overlap should be substantial. pnmstitch shifts and stretches the right hand image to match it up the left hand image. You probably want to crop the result with pamcut to make a nice rectangular image.
If you're just trying to join (concatenate) two images at their edges, use pnmcat.
The left_filespec and right_filespec arguments are the specifications (names) of the PNM files containing the left hand and right hand images. If you specify only right_filespec, the left hand image comes from Standard Input. If you specify neither, both images come from Standard Input as a multi-image file containing first the left and then the right image.
output_filespec is the specification (name) of the output PNM file. The -output option also specifies the output file. You cannot specify both the argument and the option. If you specify neither, the output goes to Standard Output.
This program was added to Netpbm in Release 10.7 (August 2002).