term% cat index.txt 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 α 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 Im‐
ages,'' Computer Graphics, Vol 18, No. 3 (1984), pp. 253-259
BUGS
All pictures must have identical CHAN= attributes.
LAM(9.1)