Ghostscript Multipage PDF to PNG

Question

I've been using ghostscript to do pdf to image generation of a single page from the pdf. Now I need to be able to pull multiple pages from the pdf and produce a long vertical image.

Is there an argument that I'm missing that would allow this?

So far I'm using the following arguments when I call out to ghostscript:

string[] args ={
                "-q",                     
                "-dQUIET",                   
                "-dPARANOIDSAFER", // Run this command in safe mode
                "-dBATCH", // Keep gs from going into interactive mode
                "-dNOPAUSE", // Do not prompt and pause for each page
                "-dNOPROMPT", // Disable prompts for user interaction                           
                "-dFirstPage="+start,
                "-dLastPage="+stop,   
                "-sDEVICE=png16m",
                "-dTextAlphaBits=4",
                "-dGraphicsAlphaBits=4",
                "-r300x300",                

                // Set the input and output files
                String.Format("-sOutputFile={0}", tempFile),
                originalPdfFile
            };

Answer 1

First check the output device options; but I don't think there's an option for that.

Most probably you'll need to do some imposition yourself, either make GhostScript do it (you'll have to write a PostScript program), or stitch the resulting rendered pages with ImageMagick or something similar.

If you want to try the PostScript route (likely to be the most efficient), check the N-up examples included in the GhostScript package.

Answer 2

I ended up adding "%d" to the "OutputFile" parameter so that it would generate one file per page. Then I just read up all of the files and stitched them together in my c# code like so:

var images =pdf.GetPreview(1,8); //All of the individual images read in one per file

using (Bitmap b = new Bitmap(images[0].Width, images.Sum(img=>img.Height))) {
 using (var g = Graphics.FromImage(b)) {
  for (int i = 0; i < images.Count; i++) {
   g.DrawImageUnscaled(images[i], 0, images.Take(i).Sum(img=>img.Height));
  }
 }
 //Do Stuff
}