improve description for PDF resizing, and introduce alternative tool plakativ

1 files changed, 34 insertions, 4 deletions

diff --git a/USE.md b/USE.md
index 0c2ab18..c86ef0d 100644
--- a/USE.md
+++ b/USE.md
@@ -19,17 +19,47 @@ or look at underlying scripts `pdftops`and `pstopdf13`.
 
 ## Resize PDF with crop marks
 
+Simple resizing to fit target paper size
+can often be done on-the-fly at the print dialog.
+Resizing to another PDF file can however be more reliable,
+and much cheaper when passing files to a third-party printing service.
+
+Some PDF processing tools rasterize content,
+and scaling is often expressed as either exact width and height
+or a width/height scaling factor,
+only rarely as the more intuitive area factor.
+
+Resizing by scaling factor is particularly useful
+for PDF documents containing bleed and/or crop marks,
+where the the _inner_ part to fit a certain size.
+
+This example processes an A3 layout with crop marks
+placed on A3 oversize PDF pages,
+resizing to have inner part fit A4.
+
+### using plakativ (and mupdf internally)
+
+FIXME: untested!
+
+While the main purpose of plakativ is to not only resize
+but also slice onto multiple smaller tiles,
+one of its features is easy scaling by area.
+
+	plakativ --factor=0.5 --size=250mmx337mm --output=output.pdf input.pdf
+
+### using Ghostscript
+
 Ghostscript resizing is done by first defining target size
 and then tell to resize content to fit that target with `FitPage`.
 
-For a PDF document containing bleed and/or crop marks,
-setting a simple target `PAPERSIZE` would either scale too much
+Simply setting a target `PAPERSIZE` would either scale too much
 or (e.g. with `-dUseArtBox`) would loose bleed and crop marks.
-Instead we look up original width and height with the command `pdfinfo`
+Instead we first lookup original width and height with the command `pdfinfo`
 and explicitly set those values scaled down by 21/29.7
 (the ratio between A3 and A4 page formats).
 
 Example command,
-for a PDF document with width 910.24 and height 1258.9:
+for a PDF document with width 910.24 and height 1258.9
+(as reported by `pdfinfo`):
 
 	gs -o output.pdf -sDEVICE=pdfwrite -dDEVICEWIDTHPOINTS=643.60333 -dDEVICEHEIGHTPOINTS=890.131 -dFIXEDMEDIA -dFitPage -dCompatibilityLevel=1.4 input.pdf