Villainous Imposer
v0.0.13 [VI]

This is a tool written mostly for myself, made available for others. It is focused on at-home, hobbiest printing for bookbinding (or pamphlets or zines)
All the processing is done on the client side- that means your work is entirely private. I need to figure out some CORS stuff (Cross-Origin Resource Sharing) and then it should work saved to your computer/offline.
Imposition is the process of arranging multiple pages of a PDF onto a printed sheet so that they appear in the correct order after folding (some cutting may be involved)

Relevant terms, as used by this tool:
folio - a piece of paper with a single fold down the middle. part of a signature. made up of 4 pages. made up of 2 leaves
leaf - half of a folio. made up of 2 pages. if you were to "tear a page out of a book", you'd be tearing a leaf out
page - single page from the PDF, single page in the result. likely has a single page number on it
sheet - the piece of paper fed into your printer, has 2 sides
side - the front or back of a sheet of paper. The side with the lowest page number imposed on it is considered the 'front'
signature - one or more nested folios. sewn together to make a book. a single signature could make a pamphlet

The PDFs should be a "straight" PDF - 1 PDF page should be 1 result page
Do not feed PDFs already exported as a "booklet" into this tool
Multiple PDFs can be used, but at least one is needed
If the PDFs are diffent sizes, the maximum dimensions are used
Each PDF can be preceeded by N blank pages (default is 0)
Page selection can be either all (the default), , separated list of page numbers, a range defined via -. Blank pages can be inserted via b.
Invalid page numbers will be ignored, invalid input will cause an error

The PDF pre-processing is a rare need -- you'll probably want none for it. The split pages in half is useful for scans of books/when the PDF page is actually 2 book pages. When selected, the page selection values apply after the splitting happens. The crop to PDF's BleedBox mutates the PDF pages- trimming each PDF page down to whatever values are encoded in the PDF's BleedBox (reference).

If there are exactly 2 valid PDF sources, you have the option to Process Uploads as Interlaced them -- this means the odd pages will be pulled from the first PDF and the even pages pulled from the second PDF. If the page counts (after evaluating the page selections) do not align, blank pages will be used to pad out the shorter PDF to reach the length of the larger.

This has to do with your machine and the paper you're feeding into it.

To enter custom paper sizes, just type in the text field next to the drop down. Any number x number format should work. The Custom option will be automatically added to the end of the drop down

The 🔄 button swaps the width & height of the paper. It will always report Custom, even if you select a paper size, rotate and then rotate back again. Sorry

Printer Flip Paper is an important setting that needs to align with how your printer is configured/works. Printers (or people, when manually flipping!) will either rotate the paper when turning it over to print on the other side via the long or short axis of the sheet. The imposition rendering needs to reflect this correctly. This information (flip long/flip short) will also be exported in the file name. Make sure it's correct or you'll have a bad time.

The Paper Margins are to add white space on the edges of the printed page in case you do not have a full-bleed printer. They are mirrored on either side - so a 10 pt margin on the Long Sides will put a 10 pt on both sides for a total of 20 pt

The Download Test Print button will give you a zip file named vip_test_print, which contains a PDF of same name. It looks at your selected paper size and flip orientation. You should print this at 100% scale and then check several things - are you flipping correctly - how much of the corners are eaten away by printer margin (each white line and each black line are 1 pt a piece -- my printer eats 12pt on all sides) - what line weight & color you want for your various mark ups - and what kind of printer skew you're dealing with (more on that later)

This is how the PDF pages will be tiled on the printed page
Folios per Signature can take a single number (all signatures the same size) or a comma separated list of numbers of numbers for variable signature sizes (the sequence provided will be repeated if it does not account for all pages)

When entering line weigh values, be aware that you can use decimals/go lower than 1
Fold lines (dashed) are for signature assembly - they will need to be cut at some point but it doesn't have to be right away (cut during textblock trimming)
Cut lines (solid) are for signature assembly - they need to be cut at time of fold up/sewing
Cut & Fold lines will only be marked on one side of the sheet. This is the "mountain" side of the fold - you should always be able to see the fold or cut line after the fold
Crosshairs are at every non-sheet-corner intersection and are meant to be very tiny visual guides to help with alignment/folding. They are on both sides of the sheet

This is to address printer skew