TH LAM 9.1
SH NAME
lam, posit, piccat, picjoin \- combine several images
SH SYNOPSIS
B fb/lam
I input ...
PP
B fb/posit
I input ...
PP
B fb/piccat
I input ...
PP
B fb/picjoin
I input ...
SH DESCRIPTION
I Lam
overlays (laminates)
several picture files, writing the resulting picture file to standard output.
The output
B 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.
PP
I Posit
performs similarly, except that output pixels are computed by compositing the
corresponding input pixels, with later input pictures
B over
earlier ones.
If the input images have no
α
channel,
I posit
has the same effect as
IR lam .
PP
I 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.
PP
I Picjoin
is similar, but joins the pictures left-to right.
SH SOURCE
B /sys/src/fb/lam.c
br
B /sys/src/fb/posit.c
br
B /sys/src/fb/piccat.c
br
B /sys/src/fb/picjoin.c
SH "SEE ALSO
IR picfile (9.6),
Thomas Porter and Tom Duff,
``Compositing Digital Images,''
I Computer Graphics,
Vol 18, No. 3 (1984), pp. 253-259
SH BUGS
All pictures must have identical
B CHAN=
attributes.

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