lam, posit, piccat, picjoin - combine several images
fb/lam input ...
fb/posit input ...
fb/piccat input ...
fb/picjoin input ...
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 corre-
sponding input pixels, with later input pictures over earlier ones. If the input images
have no a 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.
picfile(9.6), Thomas Porter and Tom Duff, ``Compositing Digital Images,'' Computer Graph-
ics, Vol 18, No. 3 (1984), pp. 253-259
All pictures must have identical CHAN= attributes.