Note:
imagewidth and imageheigh do not return the actual width and height. Instead they are 2 times the actual width and height. I don't understand why, but this seems to be the case with multi page tiffs (and maybe other images). In order to insert a multi page tiff into a PDF without out of control extra space do the following:
<?php
$pdf = pdf_new();
pdf_set_parameter($pdf, "licensefile", "/etc/pdflib/licensekeys.txt");
pdf_open_file($pdf, "/tmp/tifftest.pdf");
for ($i=1; $i<=4; $i++) {
$image = pdf_open_image_file($pdf, "tiff", "/tmp/test.tif", "page", $i);
$w = pdf_get_value($pdf, "imagewidth", $image);
$h = pdf_get_value($pdf, "imageheight", $image);
pdf_begin_page($pdf, $w/2, $h/2);
pdf_place_image($pdf, $image, 0, 0, 0.5);
pdf_close_image($pdf, $image);
pdf_end_page($pdf);
}
pdf_close($pdf);
?>