Extract area from pdf - pdf

Question

I want to extract an area given by x-y coordinates from a pdf page. The extracted area may be stored as a page in a new pdf document. This needs to be done several times and so I would want the process to be scripted. Are there any tools / libraries that can help do this?

Answer 1

If iText (for Java) or iText(Sharp) (for .Net) are acceptable libraries for you, you can use them to import an existing page from some PDF as a template of which sections can be displayed in another PDF.
Have a look at the example TilingHero.java / TilingHero.cs from chapter 6 of iText in Action — 2nd Edition. The central code is:
PdfImportedPage page = writer.getImportedPage(reader, 1);
// adding the same page 16 times with a different offset
float x, y;
for (int i = 0; i < 16; i++) {
x = -pagesize.getWidth() * (i % 4);
y = pagesize.getHeight() * (i / 4 - 3);
content.addTemplate(page, 4, 0, 0, 4, x, y);
document.newPage();
}
As you see, the original page is imported once and different sections of it are displayed on different pages.
(iText and iTextSharp are available either for free --- subject to the AGPL --- or commercially)

Answer 2

You may use 'pdftoppm' to do this task:
pdftoppm -f <first page> -l <last page> -jpeg -x <start x> -y <start y> -W <width> -H <height> -jpeg <in file> > <out file>
For exaple, crop the area of the first PDF page from point (x,y) = (100,200), which is the upper left corner of your crop area, with a width of 50 and a height of 80 and save it to a JPEG file is done by using:
pdftoppm -f 1 -l 1 -jpeg -x 100 -y 200 -W 50 -H 80 'my.pdf' > 'crop.jpg'
If you get in trouble with your documents resolution, you can use the '-r' option of 'pdftoppm' (see the man page of 'pdftoppm' for more).
Certainly, you can easily convert the JPEG file into a PDF, if needed.

Answer 3

Using ghostscript, you can crop the pdf the following way:
gs -f original.pdf -o final.pdf -sDEVICE=pdfwrite \
-c "[/CropBox [x-left y-bottom x-right y-top] /PAGES pdfmark"
x-left, y-bottom, etc., coordinates may be substituted with the required coordinates. Note that for gs, coordinates (0, 0) are at the left-bottom of the page.
This can then be easily scripted.