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LAM(9.1)                                                              LAM(9.1)



NAME
       lam, posit, piccat, picjoin - combine several images

SYNOPSIS
       fb/lam input ...

       fb/posit input ...

       fb/piccat input ...

       fb/picjoin input ...

DESCRIPTION
       Lam  overlays  (laminates) several picture files, writing the resulting
       picture file to standard output.  The output WINDOW= attribute  is  the
       smallest  rectangle  that  contains  all of the input rectangles.  Each
       pixel of the output image takes its value from the last-mentioned input
       image  that  covers that pixel.  Output pixels not covered by any input
       image are set to zero.

       Posit performs similarly, except that output  pixels  are  computed  by
       compositing  the  corresponding input pixels, with later input pictures
       over earlier ones.  If the input images have no channel, posit has  the
       same effect as lam.

       Piccat concatenates a list of picture files, each above the next, writ-
       ing the result to standard output.  The width of the output  file  will
       be  that of the widest input picture.  If any of the input pictures are
       more narrow than that, the space to their right will  be  zero  in  the
       output picture.

       Picjoin is similar, but joins the pictures left-to right.

SOURCE
       /sys/src/fb/lam.c
       /sys/src/fb/posit.c
       /sys/src/fb/piccat.c
       /sys/src/fb/picjoin.c

SEE ALSO
       picfile(9.6),   Thomas  Porter  and  Tom  Duff,  ``Compositing  Digital
       Images,'' Computer Graphics, Vol 18, No. 3 (1984), pp. 253-259

BUGS
       All pictures must have identical CHAN= attributes.



                                                                      LAM(9.1)