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 com-
puted 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, writing 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 Dig-
ital Images,'' Computer Graphics, Vol 18, No. 3 (1984), pp.
253-259
BUGS
All pictures must have identical CHAN= attributes.
Page 1 Plan 9 (printed 4/19/24)